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	England and Wales High Court (Queen's Bench Division) Decisions
You are here: BAILII >> Databases >> England and Wales High Court (Queen's Bench Division) Decisions >> Thefaut v Johnston [2017] EWHC 497 (QB) (14 March 2017) URL: http://www.bailii.org/ew/cases/EWHC/QB/2017/497.html Cite as: [2017] EWHC 497 (QB)

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IN THE HIGH COURT OF JUSTICE
QUEEN'S BENCH DIVISION

		Royal Courts of Justice Strand, London, WC2A 2LL
		14/03/2017

INDEX

	Para No.
A. Introduction	1-8
(i) The Claimant: Mrs Thefaut	1
(ii) The first complaint: Informed consent	2-4
(iii) The second complaint: Negligence in the performance of the discectomy	5-7
(iv) Overall conclusion: Liability upon the basis of informed consent	8
B. The Facts	9-50
(i) The back pain episode of late 2011	9
(ii) The reoccurrence of back pain: End of January 2012	10
(iii) The referral to Dr Tillett	11-12
(iv) First consultation with Mr Johnston	13
(v) The consultation with Dr Tillett: 26th March 2012 and the MRI scan	14-16
(vi) The referral of the Claimant by Dr Tillett to Mr Samandouras	17
(vii) The telephone call between Mrs Thefaut and Mr Johnston on 3rd May 2012	18
(viii) The letter of advice of 3rd May 201	19
(ix) The admission of Mrs Thefaut to hospital / the consent form: 17th May 2012	20-21
(x) The surgery	22-24
(xi) Post-operative notes	25-26
(xii) Mrs Thefaut's immediate post-operative symptoms: leg twitching / bladder sensation	27-29
(xiii) Mrs Thefaut's longer term post-operative symptoms	30
(xiv) The review by Mr Johnston: 12th – 25th July 2012	31-33
(xv) Reference to Pain Clinic	34-35
(xvi) The revisional surgery: February 2013	36-44
(xvii) Subsequent reviews by Mr Samandouras
(xviii) Mr Samandouras' letter of 30th January 2017	45-46
(xix)Damages to the S2 and S3 nerves: The expert evidence of Mr Reynard on urology symptoms	47-49
(xx) The present condition of Mrs Thefaut	50
C. Issue 1: Informed consent	51-100
(i) The law	52-64
(ii) The advice given to Mrs Thefaut	65-68
(iii) Joint experts agreement	69
(iv) Analysis of the evidenc	70-78
(v) Conclusion on materiality	79-89
(vi) Causation: Was Mrs Thefaut suffering from Weakened Back Syndrome ("WBS")	90-100
D. Issue II: Was the surgery performed negligently?	101-115
(i) The law	102
(ii) Evidential problems with causation	103-108
(iii) Negligence	109-115
E. Conclusion	116-117

MR JUSTICE GREEN:

A. Introduction

(i) The Claimant: Mrs Thefaut

1. The Claimant in this case is Mrs Lisa Thefaut. She suffers from constant pain in her back and in her leg. The pain is very serious and the prospects of it dimming and disappearing over time are slim. She faces a future of discomfort. She complains of two matters.

(ii) The first complaint: Informed consent

2. First she says that she consented to surgery performed by the Defendant, Mr Francis Johnston, in circumstances where he failed to give her full and accurate advice about the risks and benefits of the proposed surgery (a discectomy). She says that as a direct consequence of the comforting and optimistic advice that he gave to her that she was reassured and this led her to give consent. In the event the surgery did not succeed and there is evidence that as a consequence of what occurred during the surgery and/or during later revisional surgery she sustained further damage to her nerves. She says that had she been properly advised she would have known that the chances of a full recovery from her back pain in particular were nowhere near as optimistic as portrayed and that she would not have consented to the surgery at all. In such circumstances she was advised that she would recover over time and her pain would resolve. She accordingly argues that Mr Johnston acted in breach of duty towards her and this caused to her to sustain pain and suffering for which she is entitled to compensation.
3. Mr Johnston is a surgeon of long standing, good repute, and vast experience. He performs in the region of 600 procedures per annum many of which are similar in nature to that which he performed upon Mrs Thefaut. In the present case Mr Johnston sent written advice to Mrs Thefaut about the risks and benefits of the discectomy that he proposed should be performed by him upon her. The letter is set out in full at paragraph [19] below. In oral evidence Mr Johnston accepted very candidly that he had not given Mrs Thefaut the advice that he recognised that she deserved. He acknowledged that the advice given was sub-standard. He also accepted that his general record keeping was not at the time up to par. Mr Johnston said that in the light of developments in the law (set out in full below) he now adopted a quite different approach.
4. I have concluded that in relation to the issue of informed consent Mr Johnston fell below the standard that the law requires of him. I have also found on the evidence before the Court that this advice did in actual fact lead Mrs Thefaut to consent in circumstances where she would not have consented if she had been given proper advice. I also find on the evidence that there is a causal nexus between the consent and the damage sustained by Mrs Thefaut. I find that Mr Johnston is liable to Mrs Thefaut upon this basis.

(iii) The second complaint: Negligence in the performance of the discectomy

5. The second complaint made by Mrs Thefaut against Mr Johnston concerned the performance of the actual surgery. It is argued that during the surgery in some way he must have caused trauma to the L5 nerve and to the S2 and S3 nerves through misuse of his instrumentation. In particular he caused a breach of the dura with the consequence that the underlying nerves were exposed to the surrounding tissue, leading to neuropathic pain. This, it is argued, is the only explanation consistent with the symptoms that Mrs Thefaut experienced post-operation. It is said that when she went into the procedure she was experiencing severe back pain but relatively mild and tolerable leg discomfort. But after the procedure there was no improvement in the back pain and she now experienced severe leg pain. It is said that this is what one would expect to experience if the procedure had been caused negligently. The Claimant argues that there is evidence that the critical part of the surgery performed by Mr Johnston was also conducted excessively quickly and this was one cause of the injury.
6. A particular feature of, and indeed difficulty with, this aspect of the case concerns the sufficiency of the evidence. It is of the very nature of a case such as this that the evidence is circumstantial. The actual injury (to the nerves) said to be the consequence of the negligence is not visible and there to be seen and evaluated. The evidence of negligence stems from inferences to be drawn from such matters as: the post-operative symptoms experienced by Mrs Thefaut; the point in time when those symptoms first occurred; the rate at which they intensified or changed over time; the extent to which there are precise and reliable records of those symptoms in post-operative medical records; whether any post-operative symptoms might be caused by other factors, etc. There is an added area of uncertainty which relates to evidence recorded during the course of a subsequent revisional surgical procedure (performed by a Mr Samandouras) that the dura surrounding the nerves had been breached leading to some degree of herniation by the underlying nerves and exposure of those nerves to surrounding tissue. There is a good deal of uncertainty about the nature, extent and timing of this breach of the dura. As for speed Mr Johnston is renowned for being an extremely fast surgeon. But it is no part of the Claimant's case that Mr Johnston has a track record of negligence. It is an occupational fact of life that such is the complexity of the central nervous system that occasionally surgeons will face claims. Mr Johnston is no exception but there is no basis for saying that his record is any way abnormal.
7. Liability in cases such as this depends upon the Court being satisfied on a balance of probabilities that the defendant fell below the requisite standard and that the negligence was causative of the damage sustained. In the overwhelming preponderance of cases the facts involve a number of singular events which enable the Court with confidence to come to a clear conclusion about causation and breach of duty. However, if the evidence is equivocal, uncertain or inadequate or leaves too many loose ends, then it is no part of the judicial function to decide a case upon the basis of a hunch, educated guess or gut feel. In such cases the only correct result is that the Claimant has not proven the case to the required standard and the claim necessarily fails. I have not found this part of the case at all easy. However, having reflected, I am clear that there is insufficient evidence for me to conclude that Mr Johnston either caused the breach of the dura, or that even if he did that he was necessarily negligent. I have set out in the second part of this judgment my analysis of why and how the evidence does not lend itself to any sufficiently clear conclusion and why I feel that I cannot fairly or properly conclude that this part of the claim is made out.

(iv) Overall conclusion: Liability upon the basis of informed consent

8. The end result is that: (a) the claim succeeds against Mr Johnston upon the basis of the issue relating to informed consent; (b) the claim does not succeed upon the basis of negligence in relation to the performance of the surgery. This case proceeded on the basis of liability only with quantum to follow if liability was established.

B. The Facts

(i) The back pain episode of late 2011

9. In late 2011 Mrs Thefaut developed an episode of back pain which resolved relatively speedily.

(ii) The reoccurrence of back pain: End of January 2012

10. At the end of January/ start of February 2012 the Claimant experienced further back pain. An entry in the GP records dated 1^st February 2012 states:

"back pain without radiation NOS lower back, no radiation no sciatica. Has had before but worse again since MRI on Saturday. No red flags. Was told she had metal shards in her hip and this is likely impacting on her movements and resulting in spasm of other muscles. On examination antalgic gait. Straight leg raise 80 degrees bilateral. Reflexes all present and equal, plantars equivocal. Desperate for some relief – in tears. Analgesia given and agreed to write to Mr Ward to try to expedite appointment."

(iii) The referral to Dr Tillett

11. The Claimant was referred to Dr Tillett. She is a Consultant in Sport and Exercise Medicine. Dr Tillett identified local tenderness over the L4/5 and L5/S1 levels and felt this was a primary lumbar problem. In a letter dated the 20th February 2012 addressed to Mrs Thefaut's GP, Dr Tillett reported that Mrs Thefaut had awoken during December 2011 with lower back pain and spasm which lasted for a few days albeit that the residual pain improved over the following month. Mrs Thefaut had various massage treatments and undertook pilates based rehabilitation and was "generally good" during January. However on the 1st February 2012 she awoke with severe low back pain and spasm. Although the spasm settled over the course of a few days she was left with severe central low back pain that was worse on the left than on the right. The pain extended through to her lower abdominal region and occasionally into the buttocks. There was, however, no associated pins and needles, numbness, tingling or symptoms suggestive of cauda equina syndrome. She arranged for the Claimant to have an MRI scan. In a report dated 27^th February 2012 Dr Tillett reported to the Claimant's GP:

"These show an isolated problem at the L4/5 level with involvement of both the disc and the facet joint. There is some irritation of the left L5 root which would account for her more recent symptoms of pins and needles down the left leg."

12. Dr Tillett recommended a CT-guided left L4/5 foraminal injection if matters did not improve.

(iv) First consultation with Mr Johnston

13. Mrs Thefaut consulted Mr Johnston, the Defendant, privately and was seen by him on 15^th March 2012. Following the consultation Mr Johnston recommended conservative treatment. He wrote to the Claimant's GP explaining that Mrs Thefaut's real concern was acute back pain. The slight numbness in the left leg was not her major complaint. There were no symptoms of urinary disturbance and no neurological signs in her legs. Dr Johnston was of the view that the condition would settle:

"For the last 6 weeks [the Claimant] has had acute back pain. She has some slight numbness in her left leg, but this is not her major complaint. The main problem is that she feels to use her own words that her pelvic organs are being brushed with a wire brush and this is a very uncomfortable feeling. She had no actual symptoms of any urinary disturbance however. Apparently she has been offered some epidural steroid injections for a proven lumbar disc prolapse. On examination her lumbar spine was diffusely tender. She had no neurological signs in her legs. I have reviewed the MRI scan which shows a small posterolateral L4/5 disc on the left.

I have explained to Lisa that as her symptoms have only been for six weeks I would recommend a conservative course because it is most likely that her symptoms will settle spontaneously over the coming weeks. An epidural steroid injection is the only injection which has any benefit in lumbar disc disease and this is mainly to help sciatica which is not really Lisa's main problem. I therefore would adopt a conservative course. If her symptoms do not settle I would be very happy to hear from her in the future."

(v) The consultation with Dr Tillett: 26^th March 2012 and the MRI scan

14. The Claimant again consulted Dr Tillett. By 26^th March 2012 Dr Tillett reported ongoing symptoms:

"I was pleased to review Lisa today (in my NHS clinic). Unfortunately she continues to be in significant pain. In addition she has developed right posterior thigh pain and numbness in the left calf. The pain also continues to refer into her lower abdomen. She is also complaining of bladder irritability and frequency (there is no saddle anaesthesia nor loss of bladder or bowel control). On examination she has reduced ability to heel raise bilaterally (approximately 50% of the expected range of movement). This is new as [the Claimant's] previous neurological exam on the 20^th of February was normal. [The Claimant] also mentioned that she has lost weight recently, though none of her symptoms pre-date the onset of her LBP [low back pain].

Given the change in her symptoms it would be prudent to undertake further investigations before considering injections or other intervention. I have referred her for a repeat lumbar MRI and also a pelvic MRI. This will take about six weeks. Lisa thought you might have quicker access? If you are able to help with this that would be much appreciated. The alternative is [that] Lisa may fund this privately."

15. Dr Tillett prescribed Gabapentin, which is for pain relief.
16. An MRI scan was taken in late March. The Report of 2^nd April 2012 states:

"As previously commented there is a broad based disc bulge of the dehydrated L4/5 intervertebral disc with a left paracentral/posterior lateral prominence which contacts and slightly displaces the left descending LS nerve root contributed to by left facet joint hypertrophy at this level. On the background of a broad based disc bulge at this level, combined with right-sided facet joint hypertrophy, there is narrowing of the disc to facet joint space but no confirmatory right descending LS nerve root compression."

(vi) The referral of the Claimant by Dr Tillett to Mr Samandouras

17. On the 30^th April 2012 Dr Tillett dictated a referral letter to Dr Samandouras (the letter appears not to have been sent until 22^nd May 2012 and was received by Dr Samandouras on 25^th May 2012). In the referral letter Dr Tillett summarised Mrs Thefaut's condition. When she had first seen Mrs Thefaut her neurological examination was normal but since March she had developed bilateral weakness of her legs (approximately 50% of expected range of movement) and at times she suffered from bladder frequency and irritability though there were no clear symptoms of cauda equina syndrome ("CES"). Mrs Thefaut had had two lumbar MRI's that had not demonstrated any CES. She had also had a pelvic MRI, trans-vaginal US and gynaecological review to exclude other causes of her symptoms. It is recorded that 18 months earlier Mrs Thefaut had experienced a worsening of her left sided hip pain and had obtained an orthopaedic opinion and an MRI. However intervention was not then advised. Dr Tillett records that her "current pains" were quite different from her hip symptoms and Dr Tillett did not feel that her hips were the primary cause of her present difficulties. All lumbar spine movements were markedly restricted and painful with little movement below L3/4. Slump test was positive with cervical flexion only. Straight leg raise was positive with ankle dorsiflexion only bilaterally but worse on the left. She was generally tender throughout the lumbar spine but there was no significant spasm. She was especially tender over L4/5 and L5/S1 centrally which reproduced her leg and lower abdominal referred pains. She had good movement in both hips with lateral hip pain at the end of the range internal rotation bilaterally. Dr Tillett sought Dr Samandouras' opinion on whether surgical intervention would be beneficial.

(vii) The telephone call between Mrs Thefaut and Mr Johnston on 3^rd May 2012

18. There was a waiting time for up to six-month for a consultation with Mr Samandouras. Mrs Thefaut decided instead to contact Mr Johnston again. He did not see her face to face. He telephoned her to discuss her situation on 3^rd May 2012. The call lasted about 4 or 5 minutes (according to Mr Johnston) and about 5 minutes (according to Mrs Thefaut).

(viii) The letter of advice of 3^rd May 2012

19. Following the telephone call Mr Johnston sent a letter of advice confirming the substance of the telephone call. It is at the heart of the claim based on lack of informed consent. It was in the following terms:

"Further to my telephone conversation with you today I am writing to confirm that I understand you have had facet joint injections which did not help your pain. I therefore think that as your symptoms are deteriorating it would be entirely reasonable to recommend surgery to your back. By taking away part of the disc and trimming up the bone that is compressing the nerve passing down to your left leg I think that there should be at least a 90% chance of ridding you of your leg pain. As I explained to you back pain is not quite as likely to settle, but as your symptoms have come on at the same time I think that there is every chance that your back pain will settle as well. The risks of surgery are fortunately very small. There is a 0.1% chance that I could damage the nerve (giving you weakness in cocking up your left foot) and there is a 2% chance that you could have a leak of the spinal fluid which would delay your discharge from hospital by a few days but would not have any long term connotations. If you would like to go ahead you can book in for surgery by contacting Jackie on the above number and she will arrange this for you."

(ix) The admission of Mrs Thefaut to hospital / the consent form: 17^th May 2012

20. Mrs Thefaut elected to have surgery performed by Mr Johnston. On 17^th May 2012 she was admitted to the Parkside Hospital for a left sided L4/L5 discectomy. A Consent Form was signed by the Claimant and the Defendant that day. It is not clear from the evidence whether the form had been sent to Mrs Thefaut in advance. Nothing turns upon this. The name of the proposed procedure was described as an "a lumbar discectomy". The sections of the form in relation to attendant benefits or risks of surgery are not completed.
21. Mrs Thefaut had a brief conversation with Mr Johnston shortly before the surgery. She said in evidence that she was under the effects of the drug Gabapentin at the time and had to be awoken. He was in scrubs. Nothing of materiality occurred during the conversation. Mrs Thefaut was intent on proceeding with the procedure.

(x) The surgery

22. Anaesthetic records show that the start time of the procedure was just after 17.30 hours and it finished at around 18.20 hours. The operation took a total of 50 minutes. The experts agreed that the most important part of the operation which commenced with the relevant intra-operative x-ray (at 18.05pm) took about 10 minutes. A dispute arose as to whether this was in fact an accurate record since on the hospital record of the operation there is a diamond shaped notation at a point in time which Mr Johnston said, in evidence, was the mark made by the anaesthetist to indicate when the incision was made which marked the start of the critical stage in the surgery. If this were correct it would suggest that the key part of the surgery took longer than 10 minutes. This was relevant given the Claimant's criticism that Mr Johnston performed the surgery excessively fast (i.e. in about 10 minutes). In the event this particular evidential point was not pursued by the Defendant. The basis upon which the Court was invited to proceed was that Mr Johnston took about 10 minutes to perform the key part of the procedure.
23. In oral evidence Mr Johnston explained in detail exactly how he performed the surgery. Mr Johnston is immensely experienced. His stated expertise according to his profile on Spire Healthcare website is in carotid disease and cerebral vascular disease including aneurysm surgery. He performs in the order of 600 procedures annually and many are similar to the surgery performed upon Mrs Thefaut. He is known to be a very fast surgeon. He was described by Mr Gullan, the expert instructed by the Defendant, as "dextrous". Whilst he has in the past been subject to litigation which has settled and he has also been subject to claims which have proceeded to trial (unsuccessfully) he does not have a record of accidents or outcomes which is abnormal. I address the implications of the issue of speed at paragraph [115] below.
24. In his evidence Mr Johnston explained that had there been any injury to L5 and/or S2 and S3, as alleged, then he would surely have seen it under the microscope. He was adamant that he did not see any such injury or trauma and that had he done so he would immediately had recorded this, in accordance with due practice and requirements. No one has suggested that Mr Johnston was untruthful in this evidence. I therefore treat as a fact that Mr Johnston did not witness any damage or trauma being caused, including any tear to the dura, during the procedure.

(xi) Post-operative notes

25. Mr Johnston prepared a handwritten note of the operation dated 17^th May 2012 which states: "Left L4/5 discectomy, Closure: staples". No post-operative instructions are set out in the Note which Mr Johnston explained in oral evidence was due to the fact that he would give post-operative instructions to ward and nursing staff orally since he was always present and available to see patients and advise staff.
26. Subsequently, Mr Johnston prepared a fuller typed Operation Note in the following terms which also records that there were no post-operative neurological symptoms and that the procedure was problem free:

"With the patient prone, I localised the L4/5 interspace and then performed the usual muscle strip. I took an intra-operative x-ray and confirmed the level and then went under the microscope and identified the L5 nerve root. I retracted this and removed a fairly good sized amount of disc material. The root was now nicely free. I then closed over a vacuum drain with vicryl and staples. The patient awoke with no obvious neurological deficit."

(xii) Mrs Thefaut's immediate post-operative symptoms: leg twitching / bladder sensation

27. Mrs Thefaut considers that she did experience post-operative neurological symptoms. Notwithstanding Mr Johnston's record, in her evidence Mrs Thefaut said that immediately following surgery she was aware of twitching of her left leg and she mentioned this to Mr Johnston who seemed unconcerned and said the symptoms would settle, and in fact quite quickly (a matter of weeks) the twitching did cease. She also explained that she had poor sensation of bladder fullness. Overnight on 17^th May 2012 she was encouraged by a nurse to urinate. She filled two bedpans but had experienced no sensation of needing to urinate.
28. The Claimant was discharged on Saturday 19^th May 2012. The discharge summary prepared by the Defendant dated 24^th May 2012 does not make any reference to post-operative back pain and suggests that the surgery was to address leg pain. It states:

"Her MRI scan showed an obvious disc prolapse at L4/5 on the left compressing the left L5 nerve root and I recommended surgery to try and help her with left sided leg pain but was not sure that her other symptoms would settle down… Post-operative course: postoperatively [the Claimant] had some relief of her left sided leg symptoms. She was ready for discharge at 48 hours post-operatively."

29. In her oral evidence Mrs Thefaut stated that upon discharge she did not feel that there had been "real change" in the level of pain being experienced relative to the period pre-surgery.

(xiii) Mrs Thefaut's longer term post-operative symptoms

30. Mrs Thefaut's evidence was that post-operatively the surgery generally exacerbated her leg pain (relative to the pre-operative position) and, save for a short period of time, did not resolve her back pain. She felt that that her left leg was weak and this became more obvious as she increased her mobility (this is recorded in physiotherapy notes of 19^th June 2012). She also became aware of reduced sensation in her vulval and surrounding area, particularly when resuming sexual relations with her husband. Her bladder problems persisted. She explained that she telephoned Mr Johnston twice and told him of her concerns but he again reassured her that her symptoms would settle. Mr Johnston accepted in oral evidence that it was relatively unusual on the part of patients to make repeated contact and he accepted that this reflected Mrs Thefaut's condition and concerns.

(xiv) The review by Mr Johnston: 12^th – 25^th July 2012

31. Following a review on 12^th July 2012 Mr Johnston expressed concern that the symptoms had not settled:

"Unfortunately [the Claimant] has not really responded to surgery in the way that I would have expected. Interestingly her pelvic pain has completely disappeared since her L4/5 discectomy. Her left leg pain is if anything worse and she has some pain on the right. Her back pain is about the same... She had no nerve root tension signs with straight leg raising being unlimited to 80 degrees bilaterally… As she is still unable to work I have given her a form to organise a scan at Kingston and she will let me know when the scan has been done and I will let her know my recommendations."

32. A further MRI scan dated 12^th July 2012 was reported upon by Dr Svasti-Salee, Consultant Radiologist:

"Comparison is made with the preoperative MRI scan of 3/03/2012. There is desiccation of the L4/L5 disc with loss of disc height and signal demonstrated. Additional low TI W/intermediate T2 W linear signal within the left lateral L4/L5 recess and surrounding the posterior elements of L4 and L5 vertebrae are consistent with the history of previous surgery and likely due to postoperative scarring There is a tiny area of high signal T2 W involving the far left lateral annulus of the L4/L5 disc together with a residual small disc bulge, The bulging disc is seen to touch but does not displace, the left L5 nerve root and the size of this bulging disc is smaller than on the previous MRI. There is no impingement on the exiting left L4 or L5 nerve roots with the neural exit foramina."

33. On 25^th July 2012 Mr Johnston was more sanguine and he wrote to Mrs Thefaut stating in encouraging terms:

"Further to your recent outpatient appointment I am writing to let you know that I have now seen your MRI scan. This actually looks very good. There is no evidence of any pressure on any of the nerves in your back accounting for your symptoms in your leg. I would hope that your symptoms will settle in time. I would like to see you in the clinic in a couple of months' time and would be grateful if you could telephone Jackie on the above number and she can arrange this for you."

(xv) Reference to Pain Clinic

34. On 27^th July 2012 the Claimant's GP referred Mrs Thefaut to the Pain Clinic where she was seen by Dr Gandhimani, a Consultant Anaesthetist. A letter dated 14^th August 2012 records that since the operation Mrs Thefaut had suffered from low back pain of a severe nature going down the posterior aspect of the thigh to the left shin. Physiotherapy and acupuncture had not helped. Dr Gandhimani proposed a left sided dorsal root ganglion/trans­foraminal steroid injection and he also recommended a course of Amitriptyline.
35. On 15^th August 2012 Mr Johnston wrote to Mr Assoufi, Consultant in Occupational Medicine, at Kingston Hospital on behalf of Mrs Thefaut detailing her clinical course and indicating that she continued to have significant left leg pain.

(xvi) The revisional surgery: February 2013

36. Mrs Thefaut consulted Mr Samandouras. She was reviewed by him on 26^th September 2012 and he recorded the history and findings: She was in severe pain; she had mild weakness of the left ankle; she had reduced sensation to pinprick on the left L5 dermatome; her reflexes were preserved. Mr Samandouras reviewed the July 2012 MRI scan, taken post-operatively. This showed "a slight" radiological improvement of left paracentral L4/L5 disc comprising the left L5 root nerve. However, this was not in keeping with the reported symptoms. He also recorded that a July MRI scan showed: "… a significant amount of scar tissue along the surgical site and compromise of the nerve root secondary to the scarring". In the letter (which was to Dr Tillett) Dr Samandouras stated that Mrs Thefaut "… denied any sphincter problems". This rather contradicts Mrs Thefaut's own evidence that she was experiencing loss of bladder sensation but it might be that the explanation lies in the distinction between symptoms such as incontinence (which Mrs Thefaut did not complain of) and a loss of sensation (which Mrs Thefaut, in her oral evidence, did not treat as a sphincter problem). He then explained that the scar tissue which was evident on the July MRI represented "a rather difficult situation". He stated as follows:

"… removing the scar tissue can always produce more scar tissue. However a combination of excision of the scar tissue and bony decompression around the nerve so there is plenty of space for the nerve, can produce improvement of the symptoms. I was clear to explain that this is unlikely to be a miraculous cure, but can certainly help the quality of her life. Mrs Thefaut is very keen to undergo any intervention that is likely to help her."

37. Mr Samandouras again reviewed Mrs Thefaut on 19^th October 2012 as a private patient and he told her that the latest MRI scan revealed an extensive amount of scar tissue with partial enhancement. He discussed the removal of the scar tissue in a second operation as a possible option and she was placed on his waiting list.
38. On 1^st February 2013 (over 8 months following the first surgery) the Claimant was admitted to University College London Hospital. She underwent a revisional left L4 hemilaminectomy, L4/5 discectomy and L5 nerve root decompression, performed by Mr Samandouras.
39. A hand written operation record was prepared by a Mr Hyam. The record records the surgeon as being Mr Hyam and Mr Samandouras as being the assistant. However, this is in my view plainly incorrect and later records, correctly, record the fact that it was Mr Samandouras who was the surgeon and Mr Hyam who was the assistant. The contemporaneous manuscript record prepared by Mr Hyam includes the following phrase: "dura not breached". This is in contrast with the operation records prepared subsequently by Mr Samandouras himself.
40. The typed operation record subsequently prepared by Mr Samandouras noted that scar tissue had attached to the dura and that some of the nerves could be seen through the dura which had been breached:

"Procedure: … there was a substantial amount of thickened scar tissue attached to the lateral aspect of the dura. Some of the fibres of the L5 nerve root were seen to transverse the incision of the disc. There was no evidence of CSF leak…"

(Emphasis added)

41. In typed outpatient correspondence dated 30^th April 2013 concerning a clinic on 29^th April 2013. Mr Samandouras stated:

"I reviewed this very pleasant 48 year old woman who underwent an uneventful left sided re-do L4 hemilaminectomy and excision of scar tissue and nerve root decompression from the left L5 nerve root on1st February 2013. I found a large amount of substantial thickened scar tissue attached to the lateral aspect of the nerve. Some of the fibres of the L5 nerve root were seen to transverse the incision of the disc. However, postoperatively [the Claimant] did not have any substantial improvement of her symptoms. I believe that this results from the long term results of neuropathic pain. Her straight leg raising is 30 degrees on the left and 50 degrees on the right. She has a very mild weakness of the left ankle dorsiflexion graded 4+ MRC. I have explained to her again the results of my surgical exploration."

(Emphasis added)

In oral evidence Mr Samandouras explained to the Court that the hand written record prepared by Mr Hyam indicated no more than that during the operation Mr Samandouras had not breached the dura, i.e. the breach pre-existed the surgery. He explained that this record was essentially prepared to provide post-operative advice to the ward and nursing staff. In circumstances where, during an operation, the dura is breached this will stand as an instruction to the ward staff to treat the patient in a different way. It often means that the patient undergoes a more protracted period of bed rest in hospital prior to discharge. Accordingly, if the dura is not breached then there is no need for extra bed rest. Mr Hyam, however, did not appear in Court to explain his recollection or understanding of this entry. If the dura was in fact in a breached state (albeit not by Mr Samandouras) it is not clear why the advice to ward staff was not that Mrs Thefaut needed extra bed rest and care due to the tear. No evidence was given as to what, if any, steps were taken during this procedure to repair the dura.

(xvii) Subsequent reviews by Mr Samandouras

42. An up-to-date MRI scan, a further CT guided injection and an alteration to Mrs Thefaut's medication was recommended.
43. The report of the subsequent MRI scan dated 6^th June 2013 states:

"On the post­ contrast sequences there is enhancing soft tissue in the epidural space on the left side with extension around the left side forming L5 nerve root within the subarticular space. This is consistent with fibrosis and is slightly more extensive than on the previous imaging."

44. Mr Samandouras also recorded his views on Mrs Thefaut in a letter, almost a year later, dated 8^th August 2014 to Dr Scott, occupational physician, OH Assist. This was in the context of a consideration by Mrs Thefaut's employer of her employment position. In that letter Mr Samandouras stated that following the partial L4 laminectomy he excised a "substantial amount of thickened scar tissue". He was able to see "a visible number of fibres at the L5 nerve root although there was no evidence CSF leak". He decompressed both the L4 and the L5 nerve roots. He observed that her main pain appeared to have "neuropathic features" and could emanate from the 2012 L4/L5 discectomy although, he acknowledged, "it is difficult to be certain on this". The ultimate prognosis was that it would be unlikely that there would be substantial improvement in Mrs Thefaut's leg pain, though he did not rule this out. He did not expect there to be a "substantial reduction in the levels of her pain".

(xviii) Mr Samandouras' letter of 30^th January 2017

45. Mr Samandouras initially proved reluctant to give evidence. This led to the Claimant issuing a summons to compel attendance. At my invitation and encouragement, Mr Samandouras sent a letter to the Claimant's solicitor dated 30^th January 2017 setting out his position, in lieu of a witness statement. He thereafter attended and gave oral evidence. In his letter he stated as follows:

"The following statement is based on this document as well as to my recollection and I believe that the following are accurate and true to the best of my knowledge.

Following exposure of the lamina of the spine I started exposing the dura from a normal territory on the side of the L3 lamina. There was a substantial amount of scar tissue attached to the dura. Dissection was performed in a meticulous, diligent fashion under the operating microscope. My aim was to remove as much of the scar tissue as possible and decompress further the nerve root from any bony compression. During microdissection I did identify a number of exposed fibres of the L5 nerve root which are not normally exposed. These are nerve filaments of the nerves normally enclosed within a sheath of dura mater. I did not see any cut nerve filaments. There was no evidence of CSF leak. After further careful dissection some small disc fragments were removed from the disc space and the nerve root was decompressed.

Although I am certain that the exposed nerve root filaments was a finding of my operation and was not caused by my dissection, I cannot express any opinion as to the significance of this finding as well as to whether this is linked to the patient's symptoms."

46. In his oral evidence in Court Mr Samandouras confirmed the gist of the written contemporaneous records and as set out in his subsequent correspondence. He explained that he encountered substantial scar tissue attached to the lateral aspect of the nerve. He accepted that this can adhere to the underlying tissues such that there is a risk that as the scarring is peeled away to reveal the nerves, the dura and arachnoid may, sometimes, tear. However he confirmed his certainty that during microdissection he identified, that is to say came upon, a number of exposed fibres which he described as "floating free". He said that these would not normally be exposed. He was unspecific as to what he meant by "floating free". He confirmed that he did not see any cut nerve filaments nor was there any evidence of CSF leak. He accepted that some nerve fibres are elastic and can retract if cut. He was unable to express any opinion as to the significance of the finding, including as to whether it was linked or caused by the surgery performed by Mr Johnston. He confirmed that it was he, and not Mr Hyam, who performed the surgery.

(xix) Damages to the S2 and S3 nerves: The expert evidence of Mr Reynard on urology symptoms

47. Expert evidence was placed before the Court, which was not subject to any material challenge as to the urological symptom experienced by Mrs Thefaut. Mr Reynard is a Consultant Urological surgeon at the Oxford Radcliffe Hospital. He saw Mrs Thefaut on 6^th October 2014 and prepared a report on the basis of this review, medical records and witness statement evidence. His assessment was a "current" (October 2014) appraisal. Mr Reynard also produced a report dated 19^th January 2017 which responded to various points raised in the skeleton argument of the Defendant about his conclusion that Mrs Thefaut's symptoms subsequent were consistent with some form of damage being caused to the S2 and S3 nerves during the surgery performed by Mr Johnston. It was accepted that this report encapsulated the core of the dispute between the parties as to the allegation that the Defendant caused damage to the S2 and S3 nerves.
48. I have set out below the entirety of Mr Reynard's report:

"The skeleton Defence raises the following issues [para 26vi] to which you have asked me to respond:

(i) 'There was and is no caudal equina syndrome'.

Cauda equina syndrome (CES) refers to the simultaneous compression of multiple lumbosacral nerve roots below the level of the conus medullaris (the conical end of the spinal cord). These nerve roots are derived from the lower most part of the spinal cord – the lumbar and sacral regions. They subserve motor and sensory function to the lower limbs, pelvic and sexual organs and to the perineum. There is no universally accepted definition of CES, but generally speaking it is taken to be the presence of low back pain, unilateral or bilateral sciatica (unilateral or bilateral pain which shoots downwards in the distribution of the sciatic nerve), saddle anaesthesia, motor weakness in the legs leading ultimately to paraplegia, motor weakness of the bladder (impaired ability to empty) with reduced sensation of bladder fullness and rectal and urinary incontinence and loss of sexual function.

While the Claimant has some of these symptoms (reduced sensation of bladder fullness, reduced sexual sensation), she does not have any disturbed bladder motor function, by which I mean the ability of her bladder to contract and generate sufficient force to maintain a flow of urine and to achieve good bladder emptying, is not impaired. So, I would not describe her as someone who has sustained a CES and I agree with the Defence in this respect.

(ii) 'The numbness is to the left side of the genitalia region rather than bilateral. This does not sit well with the theory of instrumental damage to S2 and S3'.

In my report [para 35] I noted bilateral S2 and S3 sensory disturbance, but worse on the left, which of course was the side of the L5 nerve root compression: 'Sensation in the buttocks (S2/3 dermatome) to pin-prick was reduced on the left and right side (more so on the left)'.

The operation was a left L4/5 discectomy, done for a disc prolapse compressing the left L5 nerve root. It is clearly a matter for the neurosurgical experts to decide how extensive the collateral damage to other nerve roots can be when such surgery is undertaken, but a bilateral injury as I have identified on sensory testing would I think be consistent with an instrumental injury, to both left and right S2 and S3 nerve roots.

(iii) 'It is evident that the Claimant had pre-existing symptoms of irritability and frequency'.

I agree that she had a somewhat increased urinary frequency, passing urine 1-2 hourly (3-4 hourly being what she regarded as normal). Now her bladder symptoms are essentially the reverse – a reduced sense of bladder fullness (and her daytime voiding frequency has gone back to a more normal frequency of 3-4 hourly) which is consistent with an injury to the nerves sub-serving the sensation of bladder fullness (S2 and S3), as is her reported symptom of reduced peri-urethral sensation (which she notices upon wiping herself after passing urine) and her reported loss of sexual sensation. Only when her bladder is very full does she suddenly experience a strong urge to void urine. She has diminished vulval, vaginal and clitoral sensation.

(iv) 'He notes that the Claimant is able to pass urine without difficulty, with normal strength and flow and without post void residue…'.

My understanding is that motoneurons are more tolerant of compression than smaller sensory nerve fibres, which I think is one explanation for the preserved bladder motor function (hence the normal flow and preserved bladder emptying functions). Furthermore the S4 nerve root which has not been damaged, serves along with S2 and S3 to generate bladder contraction which I think explains why the Claimant has maintained a normal flow rate and good bladder emptying.

(v) 'Mr Reynard's finding is of a diminished sensation is [sic] in the S3 and S4 dermatomes which he relates to some form of damage (he does not say what) to the S2 and S3 nerves that serve those areas. He defers to the neurosurgeons as to whether but for negligent surgery. Such symptoms as she now has in her bladder and perineum would be present'.

My findings were of an S2 and S3 sensory deficit. What compelled me to conclude that S2 and S3 nerve roots had been damaged during the operation are the symptoms of S2/3 sensory loss that the Claimant now reports which were not present before the operation, but of which she became aware within days of the operation. My conclusion was therefore and remains that this indicates the S2/3 nerves were injured during the surgery. Such an injury could only have occurred at the time of the surgery. Since I do not perform this type of surgery because I am not a neurosurgeon, it is clearly not appropriate for me to comment on the precise mechanism by which the S2 and S3 nerve roots have been injured. I do know that it is possible to injure nerves in the abdomen and pelvis, for example, by the inappropriate placement of retractors during abdominal and pelvic surgery – while uncommon, such injuries are well described and something of which all abdominal and pelvic surgeons (which includes urological surgeons) are aware.

So, in summary the temporal relationship of the onset of symptoms (absent before, present after) to the operation of 17 May 2012, is strong evidence of a causal relationship between the two, in my opinion.

(vi) '…There is no evidence of severe damage to sacral nerves at the time of the operation. Had there been such damage the Claimant would have gone straight into retention after surgery and needed catheterisation. That did not happen. If however, there was subtle aggravation to a S2 or S3 problem… this is likely to be a non-negligent consequence of competently performed surgery or could simply be part and parcel of the Claimant's neuropathic pain syndrome'.

The evidence that S2 and S3 nerve roots have been damaged are the very symptoms of S2/3 sensory loss that the Claimant now reports. Since (a) motor nerves are somewhat larger and more robust than sensory nerve (b) the bladder muscle (the detrusor muscle) receives a bilateral innervation (so it can continue to generate bladder emptying with unilateral sacral nerve injury e.g. in sacral fractures) and (c) the bladder muscle is also innervated by the S4 nerve roots on both sides, it does not surprise me that bladder motor function was preserved in this case. All these points would explain why the Claimant did not develop urinary retention.

I hope this answers the questions raised in the Defence skeleton argument."

49. Although these are issues I return to later Mr Reynard accepted in cross-examination (a) that if there was no record of S2 and S3 symptoms in the post-operative medical records then this would militate against the conclusion that the surgery performed by Mr Johnston caused any L2 and L3 damage; and (b) that one possible cause of the pain now experienced by Mrs Thefaut was "Weak Back Syndrome" or "WBS" (see paragraphs [90] – [108] below).

(xx) The present condition of Mrs Thefaut

50. The present position of Mrs Thefaut is that she experiences disabling leg pain, altered sensation and weakness in her left foot and ankle. It is argued that this is consistent with injury to the L5 nerve root. She also experiences altered sensation of bladder fullness and reduced sexual sensation which are said to be consistent with S2 and S3 nerve injuries. She continues to suffer from back pain.

C. Issue I: Informed consent

51. I turn now to the first issue which is whether the Defendant is liable for failing properly to give Mrs Thefaut proper advice as to the risks and benefits of the elective surgery so that she could decide whether to go ahead with it or, alternatively, reject surgery as an option or a least seek a second opinion and thereby defer the decision.

(i) The law

52. The law on informed consent has, relatively recently, been reformulated by the Supreme Court. The ordinary "Bolam" test for negligence does not apply. In Montgomery v Lanarkshire Health Board [2015] UKSC 11 ("Montgomery") in the joint judgment of Lord Reed and Lord Kerr (with whom Lord Neuberger, Lord Clarke, Lord Wilson and Lord Hodge agreed) it was stated at paragraphs [87] and [88]:

"87. An adult person of sound mind is entitled to decide which, if any, of the available forms of treatment to undergo, and her consent must be obtained before treatment interfering with her bodily integrity is undertaken. The doctor is therefore under a duty to take reasonable care to ensure that the patient is aware of any material risks involved in any recommended treatment, and of any reasonable alternative or variant treatments. The test of materiality is whether, in the circumstances of the particular case, a reasonable person in the patient's position would be likely to attach significance to the risk, or the doctor is or should reasonably be aware that the particular patient would be likely to attach significance to it.

88. The doctor is however entitled to withhold from the patient information as to a risk if he reasonably considers that its disclosure would be seriously detrimental to the patient's health. The doctor is also excused from conferring with the patient in circumstances of necessity, as for example where the patient requires treatment urgently but is unconscious or otherwise unable to make a decision. It is unnecessary for the purposes of this case to consider in detail the scope of those exceptions."

53. In the present case it is not suggested that the exceptions in paragraph [88] apply so that the issue is that set out in paragraph [87]. Under this test the doctor must communicate material risks and this should include reasonable alternatives or variants. "Materiality" is measured according to that which the patient would attach significance to, i.e. in the context of the decision to be taken.
54. It is common ground between counsel in the present case that the test is a mixture of the subjective and the objective. Logically, and as a matter of policy, it cannot be wholly subjective because this would engage liability in favour of a patient who was irrational or wildly eccentric yet genuine. The test whether "… in the circumstances of the particular case, a reasonable person in the patient's position would be likely to attach significance to the risk", combines subjectivity with objectivity.
55. What is less clear is as to the actual extent to which subjective factors relating to the actual patient are relevant since the greater degree of subjectivity inserted into the assessment the further one departs from the standard of the reasonable patient. Some characteristics of a patient are obvious: In particular that person's actual medical condition which would include its severity. Other personal factors may be less self-evident: such as the patient's tolerance for or stoicism towards pain, or the ability to manage pain. Other factors might be quite remote from the medical or physiological condition of the patient, such as the patients need to return to work, or the fact that the patient has suffered a recent event in his/her life (such as a bereavement or a divorce) which renders that person unusually fragile and (say) unwilling to take chances at that particular time.
56. Paragraph [89] suggests that the subjective element could extend quite far. It not only deals with the important point that risk cannot and should not inappropriately be reduced to percentages but it seems to treat as relevant in the evidential mix factors such as the effect "which its occurrence would have upon the life of the patient" which could suggest that the test would embrace, for instance, the risk that an adverse outcome could reduce a person's mobility and prevent him/her engaging in a favourite sport or pastime:

"89. Three further points should be made. First, it follows from this approach that the assessment of whether a risk is material cannot be reduced to percentages. The significance of a given risk is likely to reflect a variety of factors besides its magnitude: for example, the nature of the risk, the effect which its occurrence would have upon the life of the patient, the importance to the patient of the benefits sought to be achieved by the treatment, the alternatives available, and the risks involved in those alternatives. The assessment is therefore fact-sensitive, and sensitive also to the characteristics of the patient."

57. I have also set out below at paragraph [63] a citation from the judgment of the House of Lords in Chester v Ashfar [2004] UKHL 41 ("Chester") where (cf paragraph [86] cited below) Lord Hope expressed the policy in terms which reflect quite a high degree of subjective input.
58. Paragraph [90] of Montgomery is significant in shedding light on the modus operandi of communication. Two points emerge. First the centrality of "dialogue" is stressed. No doubt, in this day and age, dialogue can occur, for example, face to face, or by skype, or over the phone. A patient who suffers from a disability or who is abroad may engage in a perfectly adequate "dialogue" via electronic means. The issue is not so much the means of communication but its adequacy. Mr Peacock used the apt expression "adequate time and space" to describe the characteristics of a "dialogue" that satisfied the test in law.
59. The second point arising from paragraph [90] is the need to de–jargonise communications to ensure that the message is conveyed in a comprehensible manner. As the citation from paragraph [89] above makes clear this can include caution in the use of percentages. There is the risk that they can convey false degrees of certainty where, in truth, none really exists. There is also the complicating problem that a clinician who uses percentages may accurately describe his/her personal track record of success but this may be significantly higher than the average and, in the ex post facto world of litigation, experts might assess prospects of success by reference to the average and not the individual. Paragraph [90] states:

"90. Secondly, the doctor's advisory role involves dialogue, the aim of which is to ensure that the patient understands the seriousness of her condition, and the anticipated benefits and risks of the proposed treatment and any reasonable alternatives, so that she is then in a position to make an informed decision. This role will only be performed effectively if the information provided is comprehensible. The doctor's duty is not therefore fulfilled by bombarding the patient with technical information which she cannot reasonably be expected to grasp, let alone by routinely demanding her signature on a consent form."

60. Some subsequent cases have begun to shed light on percentages and risk. In Mrs A v East Kent Hospital University NHS Foundation Trust [2015] EWHC 1038 (QB) ("Mrs A") Dingemans J addressed the issue of small but significant risks and he differentiated between a 1:1000 risk, on the one hand, and 1% -3% risk on the other. He stated:

"63. The question about whether Mrs A should have been warned about the risk that the low growth on 13 May 2009 or 3 June 2009 might have been caused by chromosomal abnormality depends on whether there was a 'material risk' that B was affected by chromosomal abnormality on either 13 May 2009 or 3 June 2009. In this case that means either a reasonable person in Mrs B's position would be likely to attach significance to the risk, or 'the doctor is or should reasonably be aware that [Mrs B] would be likely to attach significance to it'.

64. The GMC Guidance makes it clear that 'a small but well-established risk of a serious adverse outcome' is significant for the purposes of obtaining consent. It is also clear from Montgomery that what is a material risk cannot be reduced to percentages, is fact sensitive and sensitive to the characteristics of the patient.

84. In my judgment the evidence did not show that there was a material risk to which Mrs A should have been alerted that B was suffering from a chromosomal abnormality. If the risk had been at the level indicated by either Dr Taylor and agreed by Dr Reardon (namely somewhere between 1 or 3 per cent), or anywhere approaching that level, then I would have concluded that both Dr Galajdova or Dr Neales should have raised it with Mrs A. However in my judgment the evidence given by Professor Flinter and Dr Howe to the effect that the risk was 1 in 1,000 or, as Dr Galajdova and Dr Neales put it, theoretical, negligible or background, was much to be preferred and I accept that evidence."

61. In Tasmin v Barts Health NHS Trust [2015] EWHC 3135 (QB) ("Tasmin") Jay J endorsed the approach of Dingemans J in Mrs A:

"115. In my judgment, Mr Whitting's third submission is correct and should be upheld. A risk of 1:1,000 is an immaterial risk for the purposes of paragraph 87 of Montgomery. The Supreme Court eschewed characterising the risk in percentage terms, but it was doing so in the context of defining the borderline between materiality and immateriality. Here, I am quite satisfied that the relevant risk was so low that it was below that borderline. I am not to be understood as saying exactly where the threshold should be defined.

…

118. In paragraph 84 of his judgment in A v East Kent Hospitals NHS Foundation Trust [2015] EWHC 1038 (QB), Dingemans J said that a risk of 1:1,000 could be described as 'theoretical, negligible or background'. Although I would agree with him in concluding that a risk of this order does not in these circumstances have to be discussed with the parents, I would prefer to formulate the matter in the following terms: that the risk was too low to be material."

62. I should briefly mention the approach adopted by the Deputy High Court Judge in Spencer v Hillingdon Hospital NHS Trust [2015] EWHC 1058 (QB) ("Spencer") where the Judge stated:

"68. In the light of the Montgomery decision already discussed above, I would express the test that I should apply to be the Bolam test with the added gloss that I should pay regard to what the ordinary sensible patient would expect to have been told. Put in the form of a question, the test I consider to be, would the ordinary sensible patient be justifiably aggrieved not to have been given the information at the heart of this case when fully appraised of the significance of it?

…

76. I ask myself the question, would the ordinary sensible patient expect to have been given the information contended for; put another way I ask myself, would such a patient feel justifiably aggrieved not to have been given on discharge the information contended if appraised of the significance of such information. I consider that, on the evidence before me, the answer to both questions should be in the affirmative."

With respect to the Judge in Spencer I do not accept: (a) that the Montgomery test is a variant of Bolam; (b) that the test can be limited to the reaction of the "ordinary sensible patient" since this has resonances of the patient on the Clapham Omnibus and underplays or ignores the subjective element which the Supreme Court has explained is a component of the test; or (c), that the test for what has to be disclosed is that which, if not disclosed, would leave the patient feeling "justifiably aggrieved". The test is what a "… reasonable person in the patient's position would be likely to attach significance to…". This describes a category of evidence that is logically relevant to the appraisal that the patient must perform. Casting the test in terms of justifiable grievance however risks diverting analysis from an assessment of the information which the patient needs to receive in order to make an informed choice. That information is not necessarily the information that the patient subjectively would like, even if not relevant, but which makes him/her cross and aggrieved if not supplied.

63. Finally, I would refer to the judgments of the House of Lords in Chester (ibid) where the Judicial Committee held (by a majority) that where in breach of duty a patient was not warned of a small risk of damage, which damage then eventuated, and the patient would otherwise have sought advice on alternatives and would not have undergone surgery at the time and in the circumstances that she in fact underwent surgery, the surgeon should nonetheless be regarded as having caused the entirety of the damage. Lord Hope stated:

"86. I start with the proposition that the law which imposed the duty to warn on the doctor has at its heart the right of the patient to make an informed choice as to whether, and if so when and by whom, to be operated on. Patients may have, and are entitled to have, different views about these matters. All sorts of factors may be at work here - the patient's hopes and fears and personal circumstances, the nature of the condition that has to be treated and, above all, the patient's own views about whether the risk is worth running for the benefits that may come if the operation is carried out. For some the choice may be easy - simply to agree to or to decline the operation. But for many the choice will be a difficult one, requiring time to think, to take advice and to weigh up the alternatives. The duty is owed as much to the patient who, if warned, would find the decision difficult as to the patient who would find it simple and could give a clear answer to the doctor one way or the other immediately.

 87. To leave the patient who would find the decision difficult without a remedy, as the normal approach to causation would indicate, would render the duty useless in the cases where it may be needed most. This would discriminate against those who cannot honestly say that they would have declined the operation once and for all if they had been warned. I would find that result unacceptable. The function of the law is to enable rights to be vindicated and to provide remedies when duties have been breached. Unless this is done the duty is a hollow one, stripped of all practical force and devoid of all content. It will have lost its ability to protect the patient and thus to fulfil the only purpose which brought it into existence. On policy grounds therefore I would hold that the test of causation is satisfied in this case. The injury was intimately involved with the duty to warn. The duty was owed by the doctor who performed the surgery that Miss Chester consented to. It was the product of the very risk that she should have been warned about when she gave her consent. So I would hold that it can be regarded as having been caused, in the legal sense, by the breach of that duty."

64. As already noted paragraph [86] of Chester cited above also suggests that quite a high degree of subjectivity is combined with objectivity in the analytical mix.

(ii) The advice given to Mrs Thefaut

65. I turn now to the analysis of the evidence in the light of the law. The starting point is the advice actually given. The letter dated 3^rd May 2012 (set out at paragraph [19] above) largely speaks for itself. It is in my judgment the most direct and compelling evidence of what Mrs Thefaut was advised by Mr Johnston about the risks of surgery. The letter records certain facts and expresses various opinions which I can summarise as follows:

(a) Mrs Thefaut had pre-existing pain.

(b) Her condition was deteriorating.

(c) It was "therefore entirely reasonable to recommend surgery".

(d) By taking away part of the disc and by trimming the bone that was compressing the nerve passing down Mrs Thefaut's leg there was "at least 90%" chance of "ridding" her of the leg pain. I observe that the 90% is expressed as a minimum ("at least").

(e) The back pain was "not quite as likely to settle". The expression "quite as likely" is a reference to the comparator of less pain.

(f) It was significant that the symptoms came on at the same time.

(g) There was "every chance" that the back pain "would settle as well".

(h) The risks of surgery were very small.

(i) There was a 2% chance of leakage of spinal fluid but if this happened it would only mean a delay in discharge.

(j) There was a 0.1% chance that in surgery Mr Johnston could damage the nerve giving Mrs Thefaut weakness in cocking up the left foot.

66. I consider next the categories of information which were not set out in the letter which were nonetheless significant to the analysis and assessment that Mrs Thefaut had to make.
67. First Mr Johnston did not set out in the letter what the likely timeframe for recovery was if the procedure did not go ahead. In his oral evidence Mr Johnston was clear that it was his opinion before and following the procedure that had the surgery not occurred then Mrs Thefaut would have recovered within 12 months at the latest and that he communicated this to Mrs Thefaut. Mrs Thefaut gave evidence to similar effect, namely that absent the surgery she had been told by Mr Johnston that she would be cured within 12 months. In her Witness Statement she recalled a conversation with Mr Johnston in which he had said to her: "If I left you on a desert island for a year with 100 other Lisa's in the same position you would almost all be better when I came back". Her recollection of this conversation was not challenged in cross-examination. Mr Johnston also accepted in oral evidence that he would have explained that (absent surgery) over the course of the 12 month recovery period the pain would have diminished progressively. None of this was in the letter even though in his earlier letter of 15^th March 2012 (see paragraph [13] above) he had considered the issue sufficiently significant to include expected recovery time as a relevant matter.
68. Second, Mr Johnston did not tell Mrs Thefaut of the inherent risk of any (non-negligent) surgery leading to an exacerbation of her condition. The experts put this risk at "up to 5%".

(iii) Joint experts agreement

69. The experts are agreed that:

(a) The chances of resolving or improving Mrs Thefaut of leg pain were circa 85%.

(b) The chance of ridding Mrs Thefaut of removing or improving back pain was circa 50%. (In his oral evidence Mr Johnston did not substantially demur for this positon agreed by the experts but he thought that the chances of eradicating back pain were nearer 60-65%.)

(c) There was an "up to 5%" chance of (non-negligent) surgery exacerbating the condition.

(d) The 0.1% chance that in surgery Mr Johnston could damage the nerve was understated ("exceedingly low") and should have been circa 1%.

(e) The 2% chance of a spinal fluid leak delaying discharge was correct.

(iv) Analysis of the evidence

70. In this section of the judgment I address various points which arose in the course of the trial which are relevant to materiality.
71. Back pain: In relation to back pain the experts agree that the chances of eradicating or at least significantly mitigating the back pain were circa 50%. This is very much lower that the chances communicated in the letter of 3^rd May 2012. The strong impression given there is that the chances of eradicating back pain were not as high as that for the leg ("at least 90%") but were not far off. And moreover the outcome being described when he uses the phrase "settle" is by reference to eradication of pain, not eradication or amelioration. Inevitably any percentage is not precise since all experts agree that the precise and actual causes of back pain are hard to pinpoint given the complexity of the nerves running through the central nervous system and the difficulty in identifying exactly which nerve is injured or compressed or otherwise the cause of discomfort. Nonetheless surgeons do know from practical experience that a substantial percentage of procedures of this type do not lead to significant alleviation of the back pain, never mind eradication. In my judgment the letter amounts to a material overstatement of both (a) chances and (b) outcome.
72. Prospects of recovery and pain trajectory: Even though oral advice had been given about the prospects of recovery and the expected naturally occurring downward trajectory of all pain (back and leg), this should have been set out in the advice. In Montgomery the Supreme Court held that alternatives and variants were matters a patient should be advised of (see the citation in paragraph [52] above). The option of having no surgery was in this case highly material because it was a very important alternative. I accept that on the facts of the present case however Mrs Thefaut was aware of this from oral conversations. Mrs Thefaut was not questioned on this in cross examination and there is no evidence before me to indicate that she was confused as to the prospects of recovery without surgery. On the contrary she emphasised that she trusted Mr Johnston and his reassurance that the procedure would bring about accelerated pain relief, i.e. relief relative to the naturally expected recovery period. But, as a general proposition, this was a critical part of the context to the advice and its omission risked confusing the patient into thinking that because it has not been mentioned as part of the formal advice, when everything else has been mentioned, it was of no real significance and/or has been overtaken and superseded by the formal written advice.
73. Leg pain: There is a difference between Mr Johnston's "at least 90%" and the joint experts who consider that 85% is more accurate. I accept that "at least 90%" is over optimistic not least because that could imply 95% or 97% both of which fall into Mr Johnston's risk bracket or range. It might be said that the difference between "at least 90%" and 85% is a relatively marginal difference and not therefore material. I would disagree for two reasons. First, 85% is statistically different in a significant manner from an indication of prospects which uses 90% as a minima. The difference between 85% and (say) 95% is 10% which is a potentially important difference. Second, on the facts of this case the "at least 90%" figure was used, in effect, as a benchmark or comparator for the assessment of back pain. Given the manner in which the advice was formulated any reasonable reader in the same position as Mrs Thefaut would have drawn from it that the chances of eradicating the back pain was closely connected to the chances of eradicating the leg pain, i.e. not far from "at least 90%", which in most circles would be seen as a near racing certainty, i.e. as the surgeon being very confident indeed. This is a far cry from a 50:50, evens, analysis, or even something slightly more optimistic. I therefore conclude that the chances of success given in relation to leg pain were substantially overestimated.
74. Inherent risks of surgery: It is common ground, and indeed evident from the letter of 3^rd May 2017, that Mr Johnston did not advise Mrs Thefaut of the inherent risk (of up to 5%) that any (non-negligent) procedure could exacerbate the existing condition. The written advice should have mentioned the up to 5% chance of any, non-negligent, procedure causing an exacerbation of the condition. It was accepted in evidence that the "up to 5%" chance was different and unrelated to the attendant risk associated with anaesthesia and it should therefore have been explained that this "up to 5%" was a risk over and above that related to anaesthesia. I consider this to be a material omission both in its own right and when viewed in the context of the other omissions or overstated assessments. First, Mr Johnston did note less significant risks (the 0.1% and the 2%) so he clearly considered orders of magnitude of less than a figure in the "up to 5%" range to be sufficiently significant that they should be recorded. Second, I draw some support from the conclusions of the High Court in Mrs A and in Tasmin (see paragraphs [60] and [61] above) both of which treat risks of this order and magnitude to be potentially significant. Third, and most significantly, when viewed cumulatively with other evidence the figure assumes an enhanced importance. In particular a combination of a 50:50 chance of success in relation to eradication of back pain in conjunction to a 5% chance of making things materially worse is highly material when compared and contrasted with the counterfactual of no operation and a recovery trajectory of up to 12 months and gradually receding pain.
75. Professionally competent patients and the inherent risks of surgery: There was a suggestion in the written expert evidence of the Defendant that there was no need for Mr Johnston to advise Mrs Thefaut fully since in relation to inherent risks she could be assumed to be cognisant of the relevant risk of surgery by virtue of her work as a midwife of long standing. In oral evidence this was not however a position that Mr Johnston himself adopted. He quite properly and fairly accepted that his duty was to provide full advice and that this included the inherent risks of surgery and this extended also to a patient who could be considered to be professionally competent. Mr Gullan, the Defendant's expert, when questioned in the witness box likewise did not ultimately seek to defend a position whereby a surgeon could make assumptions about the pre-existing knowledge of a particular patient and then tailor the advice accordingly. This must be correct. A surgeon giving advice cannot quiz a patient about his or her state of knowledge and then trim down the advice accordingly. And nor can a surgeon simply make assumptions about an individual because it is known that the patient is professionally qualified. This would render the process arbitrary and subjective. It would also make the process needlessly over complicated since the far simpler course is to proffer full advice and not shape it according to the patients perceived state of knowledge. Assumptions of this sort should therefore not be made. The clinician should simply give the relevant complete advice. On the facts of this case Mrs Thefaut gave evidence, which I accept, that she was personally aware of the risks associated with anaesthetics but not of the more general, systemic, risks of surgery.
76. The telephone conversation of 3^rd May 2012: Although there was, as is recorded in the ensuing letter, a short telephone conversation between Mr Johnston and Mrs Thefaut on 3^rd May 2012 it has not been suggested that in that conversation additional information was given by Mr Johnston. He considers that the call would have been about 4-5 minutes; this accords with Mrs Thefaut's own recollection of about 5 minutes. Mr Johnston accepted that ideally he should have seen Mrs Thefaut face to face. Perhaps if he had there would have been "adequate time and space" (see paragraph [58] above) for a fuller and more satisfactory discussion to occur.
77. Hospital consent forms: It is accepted that the simple fact that Mrs Thefaut signed the hospital consent form is not to be taken as an indication of acceptance of risk. In my view the document is of no real significance on the present facts. (It would have greater significance in emergency cases involving no prior contact between patient and clinician).
78. The pre-surgery conversation of 17^th May 2012: It is also accepted that the brief discussion between Mr Johnston and Mrs Thefaut on 17^th May 2012 immediately prior to surgery was not, by itself, sufficient to warn Mrs Thefaut of the risks and benefits. I would make one general observations about this. It is routine for a surgeon immediately prior to surgery to see the patient and to ensure that they remain wedded to the procedure. But this is neither the place nor the occasion for a surgeon for the first time to explain to a patient undergoing elective surgery the relevant risks and benefits. At this point, on the very cusp of the procedure itself, the surgeon is likely to be under considerable pressure of time (to see all patients on the list and get to surgery) and the patient is psychologically committed to going ahead. There is a mutual momentum towards surgery which is hard to halt. There is no "adequate time and space" for a sensible dialogue to occur and for free choice to be exercised. In making this comment I am not of course referring to emergency situations where the position might be quite different. In relation to the facts of the present case Mrs Thefaut's evidence was that this meeting between herself and Mr Johnston was brief, Mr Johnston was in scrubs and impatient to proceed. She felt drowsy and not in a position to question him on matters relating to risk/benefit.

(v) Conclusion on materiality

79. I now pull the evidential threads together. The approach I adopt is intended to be evidentially conservative. I start by considering the position from a predominantly objective standpoint, to arrive at a prima facie position. Then I insert more subjective criteria to test the prima facie position. As it happens, the analysis at both stages leads to the same result which is why I consider my conclusion to be evidentially conservative. In my judgment a reasonable patient with the same symptoms as Mrs Thefaut, being fully and properly advised, would have either rejected the option of surgery altogether or at least deferred the option until she had received a second opinion. This is for the following reasons.
80. First, it is important to place the advice about the risks and benefits of surgery into the context of the advice given as to recovery absent the procedure. As to this the hypothetical patient is, in substance, deciding upon surgery as a means of achieving accelerated pain relief. Absent the surgery a full recovery and a dimming of the pain over time is expected. The counterfactual is hence one where the patient is measuring the risks of surgery and the chances of rapid pain relief against an alternative of a steady reduction in pain ending in full recovery in a period where the outer limit is about 12 months. For this reason, logically, any increase in the risks of surgery and/or a reduction in the prospect of pain reduction assume an enhanced significance. Any worsening of the odds in relation to either or both of those two matters makes it intrinsically less likely that a reasonable patient would opt for surgery and more likely that he/she would either elect to avoid surgery or at the very least seek a second opinion.
81. Second, it is also important to take into account precisely which of the risks and benefits in practical terms meant most in practice to the patient. In the present case for a reasonable patient with Mrs Thefaut's condition by far and away the most important factor influencing factor was the back pain. The leg pain was an irritant and not of the same order of magnitude of pain as that experienced in the back. For a patient enduring back pain the most important piece of the advice given is therefore that in relation to the back, and not the leg. As to this the patient was not given a percentage figure. But the language used in the letter was, for the reasons I have already given, extremely reassuring. Mr Johnston's evaluation was a relative one, i.e. the chances of eradicating the back pain were not quite as good as those in relation to the leg but, read fairly, the clear impression conveyed by the letter was that nonetheless the chances of success in relation to the back were still very high: Not quite as good as the leg, but not far off.
82. My prima facie conclusion is that a reasonable patient with Mrs Thefaut's condition would have declined surgery or at least deferred it pending a second opinion. My conclusion on the understatement of the risks of surgery causing damage to the nerve (0.1% as opposed to 1%) and the omission of a general warning about the inherent risks of surgery serve to confirm my conclusion. They are buttressing factors. I now test that prima facie position by reference to the evidence of Mrs Thefaut herself.
83. The first point is that Mrs Thefaut understood the letter in the manner described above, i.e. as giving a very high degree of reassurance that the back pain would resolve more or less completely. She understood the chances to be not quite as good as those for the leg but not far away, and that since the chances for the leg were extraordinarily high then it followed that the chances of eradicating the back pain were also very high. She did consider that the percentages related to eradication and not just partial amelioration. I accept her evidence on this.
84. The second point is that Mrs Thefaut was adamant that had she been properly advised that the chances were only 50:50 or thereabouts in relation to back pain that she would not have undergone surgery at all. She explained that she was a cautious person and that she had in fact rejected surgery as an option in the past. I have no reason to doubt this evidence. In general Mrs Thefaut was very calm and collected in giving her evidence. She had an excellent and accurate recall of the details of her case. She did not fight every single proposition put to her by counsel; she agreed with those which were sensible. Mr Hyam QC for the Defendant did not suggest that she was fabricating her evidence; it was accepted as being tendered in good faith. But he did put to her the proposition that she had allowed her evident frustration and anger at Mr Johnston to affect her views and that the truth might have been less clear cut than her present evidence suggested. He put it to her that she gave her evidence with the benefit of hindsight. In assessing Mrs Thefaut's evidence I have been conscious of the possibility that her answers might have been affected in this way. Indeed it would be only human for a person in her position, who feels strongly that a surgeon is responsible for condemning her to a lifetime of pain, unconsciously to allow those emotions to colour the evidence given. I have therefore tested all of her evidence carefully and deliberately against both the intrinsic logic of the case and against the actual documentary and scientific evidence. I have not in this regard come to the conclusion that I should discount her evidence. I accept her evidence to the effect that she would have avoided surgery. Her (subjective) evidence is entirely consistent with my analysis of how a reasonable patient, similarly placed, would have reacted.
85. The position adopted by Mrs Thefaut is also consistent with the impression that I gained from watching her carefully when she gave evidence. She is a person who is determined to manage her pain as best she can. She exercises regularly and takes the advice of a range of experts (physiotherapists, pilates experts etc). When she told me that she would not have elected surgery I have accordingly placed this answer in the context of her determination to manage her pain and overcome her ever-present discomfort. She is not in my view a person who would have grabbed the prospect of immediate pain relief simply because it was there. Her decision would, as she explained in the witness box, have been cautious, thoughtful and measured.
86. Next, Mrs Thefaut's view was not just based upon the 50:50 point. She was also affected by the omission of the "up to 5%" risk of non-negligent surgery exacerbating the condition. A 1:20 chance whilst modest in isolation is still not a chance that can be ignored especially: (i) if the overall chance of eradicating the back pain is only 50:50; (ii) if the leg pain is not the crux of the issue and something that can be borne until it resolves naturally; and (iii), if absent any surgical intervention the back pain will also resolve itself steadily such that even acute pain could be only moderate and then low pain in due course.
87. There are four other evidential points to note. First, my conclusion is not based on the omission from the advice letter of information about recovery rates because Mrs Thefaut had that firmly in mind anyway. Second, I do not consider that either her willingness to pay for private treatment or (conversely) a desire to avoid paying for surgery were materially relevant to the decision. Third, whilst I accept that Mrs Thefaut would have wished to return to work, I do not consider that this played any significant part in her decision. Fourth, I have not gained a great deal from the views of the experts on this issue. I can see how an expert might cast some light upon how a reasonable patient might react but in the present case the analysis of both experts even on this issue did not grapple with the detail of the evidence; and they have little they can properly say about the more subjective components of the test which are very case and context specific.
88. For these reasons I accept that had correct advice been given Mrs Thefaut would have refused surgery. But at the least she would have deferred and sought a second opinion.
89. As to the position arising had Mrs Thefaut sought a second opinion I assume that for this purpose she would have been given full and accurate advice. On this basis I can see no reason why she would have taken any different position, i.e. she would still have refused surgery. Indeed that conclusion is more compelling since if her decision to refuse surgery at the earlier point in time had been upon the basis that absent surgery she would recover naturally over time, then when she went for a second opinion (which I assume would have been reasonably soon after receipt of the first advice) she would have been advised in similar times but with one difference, namely that the point in time at which she could now expect recovery would be slightly sooner that hitherto. In other words, the logic of her decision to refuse treatment initially would have been stronger not weaker at the point in time when the second opinion was given. If I then assume in the yet further alternative, that, contrary to the above, this time Mrs Thefaut decided to have surgery then I can see no reason why I should also assume that whatever unfortunate mishap might have occurred during the surgery she underwent which caused her present conditions would necessarily occur again. Mr Johnston does not have an abnormal accident rate; and there is no evidence to suggest that the success rate of Mr Samandouras is any the less. In all probability therefore had the surgery occurred on a separate day performed by either of those two surgeons then the damage would not have occurred.

(vi) Causation: Was Mrs Thefaut suffering from Weakened Back Syndrome ("WBS")

90. I turn now to causation. It is the Defendant's case (on causation) that (i) even if she had been given the full and proper advice and (ii), regardless of what happened during the procedures performed by Mr Johnston and/or Mr Samandouras, it is likely that Mrs Thefaut would still have suffered from her present condition. This was because she was suffering from "Weakened Back Syndrome" or "WBS". Mr Gullan, the Defendant's expert stated in his report (and he repeated this same point in his oral evidence):

"It remains my view that Mrs Thefaut is unlikely to have recovered sufficiently to return to work whether or not he had surgery. Unlike her previous episode this one had persisted and was proving intractable to conservative treatment. As I set out above her prognosis was in my view poor with or without surgery, and her condition and prognosis is likely to have been similar in any event"

91. If the condition presently suffered by Mrs Thefaut would have occurred quite irrespective of the advice and the surgery then Mrs Thefaut's claim fails on both grounds upon the basis of an absence of causation. However, if the present condition is caused by the procedures performed by Mr Johnston and/or Mr Samandouras (whether negligent or otherwise) then there is a sufficient causal link between the advice and the damage.
92. Before considering the evidence on this issue there is one point of law which Mr Peacock relied upon which is that if the procedure performed by Mr Johnston was not causative of the damage and it was the revisional surgery performed by Mr Samandouras that was the cause, then Mr Johnston remained liable. This was because had the sub-standard advice not been given Mrs Thefaut would not have undertaken the initial surgery with Mr Johnston and it follows that she would not then have had revisional surgery with Mr Samandouras. Hence there remained a strong causal connection between the advice and the ultimate damage. Mr Peacock relied upon the judgment of the Court of Appeal in Webb v Barclays Bank plc [2001] EWCA Civ 141 ("Webb") for the proposition that subsequent clinical negligence will not break the chain of causation unless it is held to constitute gross negligence. In Webb the Court of Appeal, in relation to medical negligence, held:

"52. However, we will consider it as a matter of substance. The question here is whether, when an employee is injured in the service, and by the negligence, of her employer, his liability to her is terminated by the intervening negligence of a doctor brought in to treat the original injury, but who in fact made it worse.

53. Unsurprisingly, there is no general rule on this question. As Laws LJ said in Rahman -v- Arearose Limited [2001] CA 351 at 366G:

'... it does not seem to me to be established as a rule of law that later negligence always extinguishes the causative potency of an earlier tort. Nor should it be. The law is that every tortfeasor should compensate the injured claimant in respect of that loss and damage for which he should justly be held responsible.'

54. The same question was considered in the High Court of Australia in Mahoney -v- Kruschick (Demolitions) Pty Ltd (1985) 156 CLR 522 where the Court (presided over by Gibbs CJ). We get from the headnote:

'Held, that if the employer were held liable in damages to the workman, it might be able to prove that if the doctor had been sued by the workman, the doctor would have been liable for some of the damages recovered by the workman, and, in that event, the employer would be entitled to an order for contribution under s.5(1)(c) of the Act.

Whether a tortfeasor can avoid liability for a subsequent injury tortiously inflicted by a second tortfeasor depends on whether or the subsequent tort and its consequences are themselves foreseeable consequences of the first tortfeasor's negligence.

Per curiam. Where an injury is exacerbated by medical treatment, the exacerbation may easily be regarded as a foreseeable consequence for which the first tortfeasor is liable. If the plaintiff acts reasonably in seeking or accepting the treatment, negligence in the administration of the treatment need not be regarded as a novus actus interveniens which relieves the first tortfeasor of liability for the plaintiff's subsequent condition. The original injury can be regarded as carrying some risk that medical treatment might be negligently given.'

55. Finally, we agree with the editors of Clerk & Lindsell on Torts, when they say:

'Moreover, it is submitted that only medical treatment so grossly negligent as to be a completely inappropriate response to the injury inflicted by the defendant should operate to break the chain of causation.' (18th Edition, 2-55)

56. We are of clear opinion that there the chain of causation was not broken. We have in mind that:

a) the original wrong-doing remained a causative force, as it had increased the vulnerability of the claimant and reduced the mobility of the claimant over and above the effect of the amputation;

b) the medical intervention was plainly foreseeable, and it was also foreseeable that the claimant's pre-existing vulnerability would impose its own risks;

c) given the doctor's conduct was negligent, but not grossly negligent, and given the findings expressed at a) and b) it would not be just and equitable, nor in keeping with the expansive philosophy of the 1978 Act for the wrongdoer to be given, in these circumstances, a shield against i) being liable to the claimant for any part of the amputation damages; and ii) being liable to make such contribution to the Trust's amputation damages as was just and equitable.

57. In short, the negligence in advising amputation did not eclipse the original wrong-doing. The Bank remained responsible for their share of the amputation damages. The negligence of Mr Jeffrey was not an intervening act breaking the chain of causation."

93. Mr Hyam QC accepted that this analysis was in principle sound. Webb shows that: (a) at base the issue is one of "substance"; (b) that the principle applies where the second "novus actus" exacerbates the initial wrongful causative act; (c) that liability will be imposed where the original wrong-doing remained a causative force. In Webb the Court endorsed the view expressed in Clerk and Lindsell on Torts 18^th edition (see citation in paragraph [55] of the judgment, supra). In the 21^st edition (2014) I note that the editors cite Webb with approval and state that ultimately the courts "… often fall back on the pragmatic approach of the common law, and invoke judicial "common sense" as a guiding principle…" (ibid, paragraph [2 – 6] page [58]). I take all of this to mean that the judicial task is to make a fair and objective assessment of all of the evidence to determine whether there remains a sufficient causal link between (here) the initial failure to give adequate advice and the ultimate injuries sustained and only something strong like subsequent gross negligence will suffice to eclipse the initial wrongful act. In my judgment on the hypothesis that it was the procedure performed by Mr Samandouras that caused the injury then in my judgment there remains a strong nexus in fact between the initial wrongful advice and the ultimate injury. This proposition was not disputed by Mr Hyam QC.
94. I turn now to the evidence. The key issue for me is to decide whether on the evidence I can preclude WBS as the cause of the present condition. This is the only cause advanced which is set against those causes advanced by Mr Peacock all of which are attributable to the surgery which was performed upon Mrs Thefaut. I emphasise therefore the limited nature of my inquiry at this stage. It is only (i) to see whether on a balance of probabilities I can exclude WBS and (ii) to determine whether I therefore attribute the cause of the damage to surgery performed by Mr Johnston and/or Mr Samandouras. If I find that this surgery was causative then that still begs a series of questions relevant to the second allegation concerning clinical negligence. These include deciding whose surgery caused the damage, and (even if it was caused by Mr Johnston) whether the surgery was negligent? But at this stage however I do not have to decide these particular issues.
95. I turn now to the questions of evidence which arise. As to these I am clear that on a balance of probabilities the present condition is attributable to the surgery which would have been avoided had correct advice been given. I summarise my findings of fact below.
96. First, the contemporary view of Mr Johnston before, during and after the surgery performed by him was that Mrs Thefaut was not suffering from WBS. He remained of the view that absent surgery her condition would both improve gradually and then resolve. Indeed he maintained this view some time after the surgery. In his oral evidence Mr Johnston, once again, fairly, accepted that this was his view. He had expected Mrs Thefaut's condition to resolve within 12 months at the latest. I am entitled to attach weight to this view. Mr Johnston is a surgeon of enormous experience. Indeed, he appears to have performed materially more procedures of this type than anyone else who gave evidence in this case. He was a fair and honest witness and expressed his views when giving evidence in a candid manner including when this was adverse to his own interest.
97. Second, as to the experts I prefer Mr Kirkpatrick's' view (for Mrs Thefaut) to that of Mr Gullan, the Defendant's expert. Mr Kirkpatrick considered that a dural tear exposing the nerves to surrounding tissue including developing scarring was the likely cause of the pain and discomfort. As such, absent the surgery which caused the dural tear, recovery could be expected. His view is consistent with that of Mr Johnston's contemporaneous conclusion (although he was of the opinion that recovery would be gradual during the first 12 months but that in an extreme case could take up to 24 months). Mr Gullan thought that recovery, if it was to occur at all, would have been evident in a much shorter timeframe and that the fact that in the circa 15 weeks between the onset of the symptoms (start of February 2012) and the surgery (Mid-May 2012) Mrs Thefaut had not shown signs of recovery indicated that her back was never going to recover and her condition was hence attributable to some more profound and incurable underlying cause (i.e. WBS). This, to my mind, was far too convenient an analysis since it just happened to fit in neatly with the actual timeframe elapsing between the onset of symptoms and the surgery and enabled Mr Gullan to suggest that this was sufficient to evidence WBS. I prefer the more rounded evidence of Mr Johnston and Mr Kirkpatrick which is consistent with the other evidence in the case about likely recovery timeframes.
98. I should at this stage make some short observations about the expert evidence that I received on this issue:

(i) Mr Kirkpatrick (for Mrs Thefaut) was of the opinion that the exposure of the nerves was an abnormal fact in the case and causative. He accepted that he had little experience of performing revisional surgery of the sort performed by Mr Samandouras. He did however construe the medical records as indicating that Mr Samandouras came across the breach of the dura but did not cause it himself and that therefore it was Mr Johnston who necessarily caused the dural breach. This was based only upon his reading of the documents. In terms of the effect of a breach he considered that the breach was likely to have occurred as a consequence of a surgical procedure and would mean that "… the nerve root is exposed to scar formation etc…". In the Joint Experts Agenda (prepared on behalf of the Claimant), Question 54 addressed the impact of any scarring over exposed nerves. The answer given (agreed to by both experts) was: "Although neither expert has direct confirmation of this, we believe that targeting of a nerve root which is not protected by a dural sheath, is likely to be a more obvious source of neuropathic pain syndrome".

(ii) Mr Hyam QC launched a sustained attack on the professionalism of Mr Kirkpatrick. This arose because Mr Kirkpatrick had in two recent cases, one in particular involving a claim for negligence against Mr Johnston which ultimately failed, been subject to serious criticism by the Court for his conduct as a professional expert witness: See e.g. Harris v Johnston [2016] EWHC 3193 (QB) per Andrews J.

(iii) More or less the full extent of the views on this important issue from Mr Gullan was in the expert's Joint Statement where he stated: "Mr Gullan has some difficulties with this concept bearing in mind in re-visiting operations, the anatomy can become extremely indistinct". He elaborated in far greater detail when giving oral evidence. He said that in a significant number of revisional procedures (of which he did many) there was an ever-present risk of breach of the dura. He considered the actual evidence based upon the account of Mr Samandouras to be unclear. He said that he had never seen "free floating" nerves in his career (though he did not comprehend what that term could actually imply or mean) but that a breach of the dura was not uncommon and not necessarily negligent; it all depended. He considered that if there was a breach it was in all likelihood attributable to Mr Samandouras.

(iv) Mr Peacock (returning fire) launched an attack on the professionalism of Mr Gullan upon the basis, inter alia, that he had failed in his report to record his prior knowledge of Mr Johnston as a colleague on various professional bodies and his regard for Mr Johnston as a surgeon of repute and skill. This was an omission going to his impartiality. He also attacked Mr Gullan upon the basis that although the issue of the findings by Mr Samandouras had been an important part of the litigation from the date of the Letter of Claim he had more or less ignored it and only really engaged with it for the first time when he gave oral evidence. He also attacked Mr Gullan for not appearing to have been aware of the actual evidence that Mr Samandouras gave in the witness box, which preceded his own evidence.

(v) In the event I took the course that I should simply listen with care to the expert evidence given by both of these experts and to the extent that there was a dispute between them I would then bear in mind any criticisms of their professionalism which I thought well founded and relevant in forming my view on the issues in dispute. My ultimate conclusion was that both experts acted properly in the giving of their evidence. I have not felt the need to discount their views on the basis of any want of professionalism. I would however make one observation. In the specialist field in issue there are a relatively small number of surgeons. They tend to know, or know of, each other, especially if they have been in practice for many years and have had prior involvement with each other as colleagues serving in the various specialist professional bodies. In such circumstances there is a high probability that when one of this select group is instructed to act as an expert in a case he or she may know of the Defendant either personally or by repute. This was the case of Mr Gullan in relation to Mr Johnston. He knew him both from co-participating in professional bodies and by repute. This did not in my judgment necessarily mean that he could not give expert evidence in the case. He was not so close to Mr Johnston that, objectively speaking, his independence was compromised. But it is my view that Mr Gullan would have been far better to get out in the open his personal knowledge of Mr Johnston. A concise but accurate and comprehensive paragraph in his report setting out the bare facts of his knowledge of Mr Johnston would have sufficed. This would have taken much of the sting out of the cross examination which did, I am bound to say, leave Mr Gullan feeling and sounding defensive. The issue here is the appearance of bias. The inevitable questions in cross examination which followed from the omission were along the lines that Mr Gullan was advancing a view which was tailored to support a fellow professional who was in a predicament, and hence lacked objectivity. If this had in fact been Mr Gullan's intent and object when giving evidence it would have struck at the very heart of his professionalism and objectivity and it could have rendered his evidence inadmissible: see, e.g. EXP v Dr Charles Simon Baker [2017] EWCA Civ 63 at paragraph [49] per Irwin LJ. As I have observed I do not accept that Mr Gullan gave his evidence other than objectively and independently.

99. Third, I accept on the evidence before the Court that there was a tear to the dura which was abnormal. Mr Samandouras in evidence stated that he saw the nerves "floating free". There is a lack of clarity as to exactly what he meant by this or as to the extent and nature of any herniation. But the impression given is that the nerves were no longer tightly packed as they would ordinarily be inside the sheath and that to some degree there was looseness and lateral mobility as between the nerves herniating through the sheath. It has not been contended by the Defendant that this breach could have arisen spontaneously. The breach therefore occurred at some point during one or other or conceivably both of the surgical procedures performed upon Mrs Thefaut. It was accepted in evidence that depending upon the size of the dural breach and the extent to which the nerves within the sheath herniated out, that the nerves could come into contact with surrounding tissue, whether of the disc, other tissue or the scarring which gradually covered the tear. In such circumstances contact between nerves and surrounding tissue could cause the present pain.
100. In conclusion in my judgment upon the evidence I conclude that WBS is not the cause of the pain and suffering. The cause of the pain was the breach to the dura causing the herniating nerves to come into contact with the surrounding tissue. Further, during one or other or even both of the procedures there was some degree of contact between the surgical instruments and L5 causing leg symptoms and the S2 and S3 nerves which caused or exacerbated adverse bladder and sensory symptoms. I should add for the sake of completeness that it was not suggested that the cause was cauda equina syndrome (see the analysis of Dr Reynard set out at paragraph [48] above). And nor has there been any serious suggestion that the condition was caused by historical problems Mrs Thefaut experienced in relation to her knees and hips. The only sensible candidates were WBS or some event occurring during the surgical procedures. This then completes the final step in the analysis. It means that in my judgment the breach of duty on the part of Mr Johnston in the advice that he gave was causative of the Claimant's condition and he is liable accordingly.

D. Issue II: Was the surgery performed negligently?

101. I turn now to the second part of the claim.

(i) The law

102. This part of the case is based upon traditional negligence applying the well-known Bolam test. As I observed in the introduction (see paragraphs [5] – [7] above) to this judgment I have found this a difficult part of the case to assess, because of the lack of clarity as to the actual evidence. I do not propose to set out a lengthy rendition of the law. The test is laid down in Bolitho v City and Hackney Health Authority [1997] UKHL 46; [1998] AC 232. As it applies to expert evidence a summary is provided in C v North Cumbria University Hospital Trust [2014] EWHC 61 (QB) at paragraph [25]. This was more recently cited with approval by Jeremy Baker J in Amanda McGuinn v Lewisham and Greenwich NHS Trust [2017] EWHC 88 (QB) at paragraph [11].

(ii) Evidential problems with causation

103. I have set out above in Section C my conclusion that it was the one or other or even conceivably both of the surgical procedures that is the cause of the pain and suffering. However, this conclusion does not entail a finding as to (a) who caused the breach and (b) whether it was negligently caused. An answer to these two more specific questions goes quite a long way beyond the more limited finding that I have made that WBS is not the cause of the condition. In seeking to form a view on these two questions I am confronted with a dearth of hard evidence. The following is a selection of only some of the many imponderables arising in relation to the procedures in issue :

Who caused the dural breach (Johnston / Samandouras / both)?

How extensive was the breach?

Were the S2 and S3 nerves contused or damaged at the same time as the dural breach or by the "other" surgeon during the "other" procedure?

Whether any of the underlying nerves were in fact cut and because of their natural elasticity they then immediately retracted out of sight inside of the sheath so that they were invisible under the microscope?

The extent to which the exposed nerves herniated and if so to what extent (what is meant by "free floating")?

The extent to which "free floating" nerves actually came into contact with surrounding material including scar tissue as it developed over time?

How fast the scarring developed and its extent (Mr Samandouras suggested it was quite substantial but the actual extent remains unclear). In their Joint Statement the experts accepted that post-operative scarring was inevitable but its relevance to WBS was "disputed". It is however an agreed expert conclusion that adverse consequences associated with scarring usually emerge over a delayed time period and are not immediately apparent after the operation. If the pain and suffering is contingent, even in part, upon the evolution of scar tissue this could be relevant to the evolution of Mrs Thefaut's symptoms over time.

The extent to which the dura adhered to the scarring following the first surgery?

104. There is also uncertainty as to the nature and evolution of post-operative symptoms. If, to take a paradigm illustration, a patient's symptoms post-operation are very clearly recorded in medical records as severe and can readily be seen to amount to a step change in pain and suffering relative to the pre-operative position and where the pain is quite discrete (so that it can be differentiated) from any normal post-operative discomfort due to the procedure or anaesthesia, then that would count as evidence that something occurring during the procedure caused those symptoms. In the present case there are many uncertainties and ambiguities and the evidence is a long way from the paradigm. I set out below some examples (though by no means all) :

The contemporary post-operative medical records do not describe symptoms that reflect Mrs Thefaut's own evidence. The Claimant says that this is due to Mr Johnston's poor record keeping. The Defendant says that this is because the symptoms now articulated were not in fact evident post-operation.

Some of the symptoms reported by Mrs Thefaut were ambiguous, such as twitching in the leg (see paragraph [27] above) which did resolve in a matter of a few weeks.

Other symptoms such as reduced sensation of bladder fullness (see paragraph [27] above) could be attributable to the effects of the anaesthetics or the temporary impact of the surgery on the body, as Mr Gullan postulated.

Mr Reynard reported symptoms experienced (as of October 2014) after both procedures. He accepted that if hospital records were accurate then the symptoms he identified as indicative of being caused by instrument damage could not so readily be attributed to Mr Johnston's surgery (see paragraphs [47] and [48] above).

105. There are also some uncertainties about the procedure performed by Mr Samandouras. These include:

The relevance of the note made by Mr Hyam, the assistant to Mr Samandouras, that the dura had not been breached (see paragraph [39] above).

The extent of the inherent risk of breach of the dura during revisional surgery. Mr Gullan who did have considerable experience of revisional surgery was of the opinion that dural breaches were not uncommon during this sort of procedure. He made the point that the risk in the case of any particular individual might also be variable and could depend on all sort of factors including the extent to which the dura had adhered to the scar tissue or surrounding tissue (so that when it was pealed away during the revisional procedure it tore), the volume of surrounding scar tissue, and the strength of the dura and the arachnoid, etc. Mr Kirkpatrick accepted that he had, relatively speaking, very little experience of such revisional procedures.

The meaning of Mr Samandouras' comment that the nerves that he visualised during the revisional procedure were "floating free".

106. At this stage I should set out, briefly and for the sake of completeness, a procedural issue that arose in relation to the evidence. Mr Samandouras was originally unwilling to give evidence. The reasons for this have not been established. He was issued with a summons to attend. In the event he sent a letter in lieu of a witness statement (see paragraph [45] above) and he attended and gave oral evidence. The Defendant objected to Mr Samandouras giving oral evidence. I ruled that he could and said that I would give reasons in the final written judgment. I granted permission because: (i) the medical records relating to the revisional procedure (see paragraphs [36] – [44] above) were clearly in evidence and could be relied upon by both parties and had been the subject of expert commentary; (ii) in such circumstances it was artificial to preclude Mr Samandouras giving evidence to explain the contents of those documents; (iii) whilst his evidence was in my view helpful to the Claimant it was also open to the Defendant to cross-examine Mr Samandouras in order to highlight possible uncertainties in the evidence; (iv), it could therefore be helpful to the Defendant in muting the effect of the written documentary records; and (v), I was clear that I could ensure that there was no procedural unfairness to the Defendant. As to this latter point I directed Mr Peacock to lead Mr Samndouras in chief having written down and provided to Mr Hyam QC the questions he proposed to put, so that Mr Hyam QC was not taken by surprise. I then allowed Mr Hyam QC the additional preparation time that he felt he needed after examination in chief to prepare for cross examination. Ultimately the personal stakes for all parties were high in this case and provided I could ensure procedural fairness I considered that I should admit the evidence. I should add that following Mr Samandouras' evidence I was not entirely clear that his recollection of events was much more than that which he had recorded at the time. It has to be remembered that surgeons in this area perform a huge number of procedures and the ability for any such professional to recall precise details of one procedure some 4 or 5 years later out of the general multitude is by its nature limited.
107. I am also struck in relation to the issue of negligence by Mr Johnston's evidence, which I accept, to the effect that he did not observe any dural tear or other damages to the S2 or S3 nerves during the procedure. He said in oral evidence that had there been damage he would have seen this on the microscope image and he said that he would have recorded this in the operational notes. I am certain that he would have acted in this way had he witnessed anything untoward. He said that he did not see how he could possibly miss such damage had it arisen. Mr Johnston accepted that normally (though he accepted not always) a dural tear was accompanied by a leak of cerebrospinal fluid (CSF). He did not witness any such fluid. He was also of the view that it was difficult to conceive how he could have damaged the S2 and S3 nerves during the operation since these were retracted out of the way during the procedure so that they could not be affected during the remainder of the decompression procedure. I entirely accept Mr Peacock's point that none of this is conclusive and it is possible that Mr Johnston simply failed to observe that which was before his eyes under the microscope. On the other hand it is a peculiar feature of the case that if damage was inflicted it should have been of such a nature that it would instantly have been visible, yet was not picked up. I make this observation in the context of an observation by Mr Gullan in oral evidence, which was not challenged by others, that the risk of dural breach is more likely during a revisional procedure than in relation to a procedure on a virgin spine, due to the risk that in a revisional operation in peeling away scar tissue (which was a consequence of the initial surgery) to expose the dura there is a risk that adhesion of the dura to the scar tissue can result in the former tearing during the peeling back process.
108. I have concluded that when I consider the evidence piece by piece and in the round I am not able to draw any clear links between post–operative symptoms and Mr Johnston's surgery which would enable me confidently to conclude that I could infer from the symptoms that they were caused in all likelihood by Mr Johnston's surgery.

(iii) Negligence

109. I turn now to the issue of negligence. I can deal with this relatively briefly.
110. This is only relevant if I conclude that it was Mr Johnston who in actual fact breached the dura and as to this I have decided that I cannot so find on the evidence as it stands. I therefore proceed to address negligence upon the alternative basis that I am wrong in my conclusion on causation: If Mr Johnston caused the dura to breach was this negligent?
111. My first point is that, as explained above, the evidence as to what actually happened is beset with uncertainties. I do not feel that it is open to me to express a view. Critically I do not know whether it can properly be said that any breach at all of a dura on a virgin spine (i.e. without exception) must be negligent. This was not an issue which was really explored in any depth during the trial. If it were true and I were to so hold it would, I perceive, be a potentially very far reaching finding and conclusion. I would not wish to form such a conclusion unless I was confident (i) that I knew what all the relevant facts actually were and could make findings about them and (ii) that I had before me a really detailed appraisal and exposition by experts of the science of breach of a dura on a virgin spine (which I do not have).
112. It must also follow from the above that if it is the case that not every breach of a dura on a virgin spine is negligent then before a Court can find negligence it must have at its disposal all of the facts and evidence which enable it to differentiate between a negligent dural breach and a non-negligent dural breach. Again I simply do not have this evidence before me.
113. Moreover if, ex hypothesi, it is not always negligent to breach a dura that might serve only to cast the spotlight on the duty of a surgeon to repair a tear. And this, in turn, may depend on whether the tear has been noticed. It could in principle be a breach of duty to fail to repair a breach or tear which was caused by a surgeon even if caused non-negligently, provided it is evident. The present claim has not been framed in terms of a negligent failure on the part of Mr Johnston to repair a breached dura; this was not explored in evidence; and the underlying medical science was touched upon only tangentially.
114. For these reasons I am clear that I cannot find for Mrs Thefaut upon this particular basis.
115. There is one final matter I should mention. This concerns speed: The Claimant alleges that the speed at which Mr Johnston performed the surgery was such that it is materially more likely that he caused the harm and did so negligently. Mr Peacock likened what he said occurred to a person driving at great and reckless speed in a 30mph limit. At first blush, when the point was first presented to me, it looked like rather a good point for the Claimant. But on reflection it is a much more complex and nuanced issue. As a very general proposition speed is relevant. But speed is a highly relative concept. Mr Johnston accepted that he was fast. He knew this as a relative concept. From his perspective he simply did what he did at the speed he was comfortable with but he was nonetheless aware that others took longer and some significantly longer than him over the procedure. There are two points to make. First, Mr Johnston accepted that he had become faster over the years and that he was very much slower when he started out. He had performed literally thousands of such procedures and that experience made him intimately familiar with every tiny aspect of the surgery. What might be super-fast to a (relatively) inexperienced Registrar might be only moderate speed to a highly experienced top consultant. This means that to some degree speed is a function of familiarity and experience. Second, I do not accept Mr Peacock's analogy with driving at great speed in a 30mph limit. In this field there are no speed limits. A speed limit on a road is deliberately set to reflect known risks and therefore to drive at great speed in a 30mph limit is to behave in a way which disregards the known risks which have deliberately led the road traffic authorities to attribute a particular speed limit. That is not an accurate analogy in the present case. It is no part of the Claimant's case that Mr Johnston has an abnormal record of accident or mishap. There is accordingly no clear evidence that performing procedures at Mr Johnston's speed in and of itself increases risk for him, even if, to test the augment, it would for another surgeon. Ultimately I have not had to decide this case upon the basis of speed but I have also not found the issue to be as indicative as at first blush it might appear to be.

E. Conclusion

116. For all the above reasons the claim succeeds on the basis of informed consent. It fails on the basis of clinical negligence.
117. I will now hear submissions on how the quantum stage of the trial should proceed.