Wootton v Accident Compensation Corporation

IN THE DISTRICT COURT AT WELLINGTON [2014] NZACC 77 UNDER The Accident Compensation Act 2001 IN THE MATTER OF an appeal pursuant to section 149 of the Act (Appeal No. ACR 316/12) BETWEEN LAWRENCE WOOTTON Appellant AND ACCIDENT COMPENSATION CORPORATION Respondent Hearing: 30 January 2014 Appearances: Ms C O Parry-Canet for appellant Mr J Coates for respondent Judgment: 24 March 2014 RESERVED JUDGMENT OF JUDGE D A ONGLEY [1] This appeal concerns a treatment injury claim. The basis for the claim is a delay in correct diagnosis of cauda equina syndrome and failure to provide treatment in a timely manner. [2] The appellant had a chronic back condition. On 2 July 2010, he developed symptoms of spinal cord compression and was referred for an MRI scan by Christchurch Radiology Group (GRG). The scan was conducted on the morning of 2 July. Radiology staff did not identify symptoms of possible cauda equina syndrome, in particular symptoms of loss of bladder sensation and function that would have required further examination and diagnosis. The appellant says that he had those symptoms at the time of his MRI scan but was sent home, where he was attended by his GP but not admitted to hospital. St John Ambulance services were called in the very early hours of 4 July. Fully developed symptoms of cauda equina syndrome were diagnosed at 4.50 am and the appellant was admitted to surgery for decompression of his L3/4 disc. He did not fully recover and suffered paralysis. [3] The respondent says that a diagnosis of cauda equina syndrome was not reasonably possible in the circumstances in which the appellant presented, until the early hours of 4 July. The appellant says that he presented with the symptoms at the time of the MRI scan in the morning of 2 July, and that timely treatment would have significantly improved his outcome. [4] A central part of the evidence concerns the appellant's general practitioner. The appellant does not directly allege medical negligence on the part of his general practitioner, but says that in hindsight all the signs were there at a critical time and he should have been admitted urgently to Christchurch Hospital. As the general practitioner was not notified as a party entitled to be heard in the appeal, she will be afforded anonymity and described as Dr A, the initial A not being the true initial of her surname. Background [5] Mr Wootton had an MRI scan on 31 May 2008 on referral from orthopaedic surgeon Mr John Rietveld, who had examined him on 22 May. He had suffered a level of back pain for some years after a fall from a ladder. Mr Rietveld recorded that the symptoms at the time of examination was right leg pain, involving a shooting sensation and electric shock sensation in his right leg. The sensation was quite different from his pain in the past. Mr Rietveld diagnosed probable discogenic leg pain probably from the 15/S1 disc, but thought that he might have some problem higher up as well. That was confirmed in the May 2008 MRI which reported: "Right sided disc extrusion at L4/5 with likely compromise of the right L5 nerve root Subarticular recess narrowing on the left at L3/4, of doubtful significance given the right sided symptoms." The events in July 2010 [6] Mr Rietveld examined Mr Wootton again two years later on 24 June 2010. Mr Wootton reported that after doing a lot of lifting and carrying, his symptoms really got bad again; the pain was in the lower back and radiated down the back of both legs, occasionally down to the feet. He said that he had a little bit of a problem with bladder and bowel. He said that he struggle to walk for any length of time. He had normal lower sensation and reflexes. [7] Mr Rietveld's diagnosis was that Mr Wootton had significant mechanical back pain which had been exacerbated by doing a lot of recent lifting. He ordered an MRI scan "to see exactly what is going on here to see if something like a cortisone injection maybe of benefit to him". [8] The MRI report was timed at 8.02 am on 2 July 2010 and coincided with an acute deterioration in Mr Wootton's symptoms. He says that, on arrival at the CRG on 2 July, he was experiencing a further increase of his lower back and leg pain to the extent that he needed to be aided by the radiographer onto the MRI table. The radiology report found no significant disc abnormality at L1/2 and L2/3 but continued: "L3/4: Loss of disc height and T2 disc signal. Since the previous MRI scan, there has been development of a large left paracentral disc extrusion which completely occupies the left subarticular recess and extends posteriorly into the posterior epidural space. This is resulting in a relative moderate-severe spinal canal stenosis with displacement of the cauda equina nerve roots into the right side of the spinal canal and complete effacement of CSF. L4/5: The previously demonstrated right paracentral disc extrusion he has largely resolved, with persisting broad-based posterior disc bulging. Mild bilateral subarticular recess stenosis, but no obvious neural compression. L5/S1: No new change to the previous study." [9] The crucial piece of radiological evidence was the large left paracentral disc extrusion at L3/4 which resulted in a moderate-severe spinal canal stenosis with displacement of the cauda equina nerve roots. That would appear to be an indicator for considering a possible diagnosis of cauda equina syndrome, but the answer to that question depends entirely on expert medical opinion. The appellant's submission that the radiologist should have recognised a need for emergency hospital admission is an attractive argument, but the conclusion depends on medical evidence. [10] On 2 July, the CRG MRI protocol sheet was signed only by the radiology technician and recorded that it was a non-supervised MRI. Ms Parry-Canet said that Mr Wootton recalled seeing only one medical person at the time, and that would have been the technician. He probably did not see radiologist Dr Oram. [11] Mr Wootton's account of his symptoms at the time of the MRI, and his presentation is taken from a number of medical notes and reports that follow. [12] Dr A was Mr Wootton's general practitioner. She made a house call in the afternoon of 2 July after the MRI. In view of the timing, her note is very important. She would have recorded it later when she was in her clinic: "Subjective Req for visit for IM analgesia. visited. Very uncomfortable with back pain after being at Radiology this a.m. Objective O/E Lying on bed. No weakness moving all limbs. IM Diclofenac 75mg given." [13] Dr A did not record a complaint of bladder or bowel dysfunction. Mr Wootton gave some brief evidence at the appeal hearing. He said he was on quite a bit of medication. He had to be helped on the MRI table because he was in pain. After the scan he asked for a disc and the person (the technician) showed him the disc and explained the severity. He did not think that he mentioned bladder or bowel issues to the radiologist or technician. He was told he was OK to go home. Dr A did not arrive until late in the afternoon. She gave him and injection to relieve the pain. He did not remember detail of the visit, only that he recalled Dr A lifting his legs. He could not remember giving information about his bladder or bowel. When he woke on the Saturday he seemed to be OK but he said that the pain was masking the severity of what was going on. He stayed in the bed thinking that was the right thing to do. He said he had a loss of sensation and could not tell without looking whether he was urinating. That was both before and after the visit from Dr A on the previous day. [14] Ms Parry-Canet for the appellant said that Dr A would have had the radiology results by 10.19 am that morning and would have known that the scan showed cauda equina roots displacement. It was also submitted that the presence of bladder and bowel problems were known to Dr A before 2 July 2010, as well as the sudden increase of lower back pain and leg pain. I note that Mrs Wootton gave evidence at the review hearing and said that she asked Dr A if she wished to view the MRI scan and Dr A said no. Whether there were facilities to view the disc is not known. [15] Symptoms described in the ambulance record at 1.00 am on 4 July included increasing pain in lumbar region and paralysis in lower left leg; pain and paraesthesia, reduced sensation and movement, in left foot; numbness in groin region; bowel obstruction; unable to stand and walk. [16] A hospital record headed "Emergency Nursing Documentation" recorded "tonight unable to feel sensation to pass urine". That note was not timed but was before 3.00 am on 4 July. The notes recorded catheterisation at 3.15 am, referral to orthopaedic registrar at 3.20 am and transfer for theatre at 6.10 am. Medical notes were completed by neurosurgeon Ms Suzanne Jackson at 4.50 am "acute cord compression" and: "[increasing] pain [2 days] ago, sciatic down initially [left] then both legs. Developed [decreasing] sensation legs; spread, now perineal numbness. No [bowel motion 2 days]. Last [passed urine] 2100 yesterday, noticed difficulty. Now IDC in situ." [abbreviations expanded] [17] A record of symptoms on admission stated: "Mr Lawrence Wootton is a 69 year old male who was transferred to the Neurosurgery service after being admitted to the Orthopaedic Department on 03/07/2010. He described sudden onset of bilateral lower extremity weakness which was profound in nature on examination with 0/5 function in the ankle, 0/5 function in the knees and 2/5 hip flexion. He had patchy sensation in the anterior thighs with absent sensation in the legs and saddle anaesthesia. He also suffered bowel and bladder disturbance with complete loss of bladder function for over 10 hours. He was taken to the operating room on an emergency basis with a diagnosis of cauda equina syndrome." 18] Ms Jackson performed spinal surgery on the appellant at about 9.30 am on 4 July. The operation note recorded: "... At the L3 level a very large fragment of disc was seen to be protruding posteriorly, partly splaying the ligamentum flavum and distorting and displacing the thecal sac towards the right side. This fragment was grasped with the pituitary forceps and upon removal a large amount of disc measuring roughly 3 x 4cm in size was pulled out as a contiguous fragment. The thecal sac was then inspected and significant bruising and microhaemorrhage was noted over the dura. We then proceeded to extend our laminectomyes laterally performing medial facetectomies at L3/4 and extensive bilateral foraminotomies. The nerve root axilla and shoulder were explored on the patient's left side and additional disc fragments were obtained from the nerve root shoulder at the level of the annulus fibrosis. A large annular defect was noted at this level and as such all soft disc was removed to prevent a recurrence. .. ." [19] The surgery produced no immediate improvement in his lower extremity function. Ms Jackson completed a hospital discharge report in which she recorded: "Presenting Complaint History of chronic back pain, increasing over the last 1-2 weeks, with pain radiating down initially left and then both legs. Developed sudden onset bilateral leg weakness with bowel and bladder disturbance - loss of bladder function for over 10 hours. MRI L-spine performed two days prior to admission. . . . Clinical Management On admission had profound weakness with 0/5 function at the ankles, 0/5 at the knees and 2/5 hip flexion. He had patchy sensation in the anterior thighs with absent sensation in the legs and saddle anaesthesia. Taken to theatre on an emergency basis on 04/07/2010. Underwent L3/4 decompression with lumbar laminectomy and removal of large left prolapsed disc. Clinical improvement in lower limb power post- operatively. Ongoing bladder and bowel disturbance, with some awareness of bladder/bowel filling. .. . Reviewed by Mr Singhal (Burwood spinal consultant) and transferred to the spinal unit to continue rehabilitation of mobility, and establish a bowel and bladder routine. ..." [20] Ms Jackson completed a treatment injury claim form on 20 July 2010. She described the treatment injury caused as "Delay in recognizing the diagnosis and instituting appropriate surgical treatment". Dr A also lodged an ACC injury claim on 10 September 2010. In the claim form she stated that the MRI scan on 2 July showed major lumbar dysfunction and that Mr Wootton was advised on admission to Christchurch Hospital that that radiologists should have referred him acutely to Christchurch Hospital for urgent surgery. The accident cause was described as "MRI performed at Southern Cross Radiology, demonstrated severe lumbar disc lesion; not acted on by Radiologists; patient subsequently developed paraplegic" [21] It is to be noted that Ms Jackson's claim form left open the point at which there had been a failure to recognise a proper diagnosis. Dr A's form referred specifically to a failure at the radiology clinic. The appellant alleges that Dr A had the radiologist's result herself, but neither party to the appeal seems to have sought information from Dr A concerning her examination and diagnosis on 2 July, or to clarify whether she had the radiology results when she examined Mr Wootton. The appellant says that bladder and bowel symptoms had occurred by the time he was examined by Dr A. [22] Mr Rietveld wrote to the ACC claims unit on 26 October 2010. By then he was acquainted with the MRI scan report, but he had not been able to access the scan on 2 July. He wrote: "Note after his MRI scan he did ring my rooms and at the time I was away and I was unable to access his films, however on the basis of the symptoms he described to my secretary, who relayed them to me we immediately told him to go to the Public Hospital, or to seek urgent attention at the After Hours or the Emergency Department. This is what Mr Wootton did and subsequently had further surgery. I don't believe his treatment was inappropriate in regard to his presenting symptoms. I believe the symptoms he was complaining of when he came to my rooms were quite different to the symptoms he had at the time of the MRI scan, that is to say his situation had changed and we were aware of this and immediately sent him through to the Emergency Department to seek further treatment which he did." [23] It would have been Mrs Wootton who made the call to Mr Rietveld's rooms. The account given in the appellant's submissions, which is not in dispute, was that Mr Wootton was driven home by his daughter from the CRG clinic and, on his arrival home, his wife had called Mr Rietveld. It was then that Mr Rietveld recommended that he seek urgent medical attention and Dr A was then called. [24] A post-operative Burwood Spinal Unit report written by Dr Singhal recorded that Mr Wootton had been complaining of weakness and being off his legs with bowel and bladder issues for the two to three weeks prior to this episode and he had developed acute retention and loss of movement in his legs especially the ankles and the knees. Mr Wootton gave evidence at the appeal hearing to correct this statement and said the symptoms developed from the morning of 2 July. In a letter on 9 December 2010, he wrote: "...the bladder and bowel issues and leg issues gradually happened between being sent home from Southern Cross MRI on 25 July 2010 and 5.30 am on Friday 4" 2010 at A&E Public hospital Christchurch. When seen by the Neurosurgeon Dr Sebastian Cogar, who asked me Could I feel pressure on my bladder?' I replied 'No!' at that time my bladder was full By 5.30 am on the 4th July 2010, I had lost movement in my legs and had Paraplegic from the waist down, losing bladder and bowel control." [25] The respondent submits that this explanation reflects a gradual onset of cauda equina symptoms that would not necessarily have been apparent at the radiology department or at the time of Dr A's home visit. That is a central question, the appellant submitting that the symptoms were enough to reasonably diagnose possible onset of cauda equina syndrome and admit him to hospital on 2 July. [26] Dr Tony Young, managing radiologist at CRG wrote on 29 March 2011: "The examination was reported by one of our specialist radiologists, Dr Byron Oram, and this was completed at 9:20am on the same day. Mr Rietveld received the report by fax and electronic transmission at 9:39am, and your general practitioner, [Dr A] received it by fax at 10:19am the same day. We have no record from the radiographer that there was anything particular about the scan or your general condition. Looking at the scan report, clearly there was a significant disc protrusion which was the likely cause of your symptoms. Finding large disc abnormalities in the spine is a common occurrence, and is not in itself a reason for urgent hospital admission. In spinal disc disease, it is the patient's overall clinical condition that determines how urgently they need treatment, and not the magnitude or extent of the imaging findings. Our protocol is that if there were concern about your general condition or the severity of the findings, the referring doctor would be telephoned and the need for any urgent arrangement discussed by phone. Loss of bladder and bowel control would be taken very seriously, but as far as I know, we had no knowledge of that at the time, and presume it developed subsequently, possibly following surgery. . . . In answer to your question about policy and procedure for radiographers referring to hospital, I can reassure you that our radiographers (who perform the scans) and our radiologists (who are the specialist doctors who report the scans) work very closely together, discuss the cases prior to scanning and adjust how the scans are performed in order to obtain the necessary information. If a patient is unwell or there is any other concern about their illness to return home, we are certainly able to refer directly to the hospital, and would normally do this after telephoning the referring doctor. If this were not possible, we would call the hospital directly to arrange admission. There are times when we summon the ambulance to collect a patient and take them to hospital, rather than expect them to travel by car." [27] The appellant says that symptoms requiring urgent hospital admission should have been recognised at the time of the MRI scan. In a later letter of explanation written to Mr Wootton, Dr Young stated: "- Your MRI scan was completed by one of Christchurch Radiology Group's qualified MRI Technologists; their training consists of a 3 year Medical Imaging degree and a 2 year post graduate diploma in MRI from Sydney University. All staff are trained in patient care and assessment. - At the time of your arrival and prior to the commencement of your scan you were given information on the requirements of an MRI scan and you were assessed by the staff as to your ability to lie in the scanner for the duration of the scanning procedure and you signed a consent agreeing to the procedure, (I have included a copy of this for your records). - The MRI Technologist and the radiologist do discuss the patient condition and the images prior to your leaving the department to ensure all required imaging to best diagnose your condition are obtained. This happened after your scan but there were no written notes obtained." [28] Dr Oram wrote in an email on 19 January 2011 "Interpretation of MRI scan: The MRI scan was well reported and interpreted accurately. Follow up/referral/advice: I cannot remember whether any follow up/referral/advice was made by myself, as the study was performed quite a while ago in the middle of last year. I do not have the original referral form to ascertain which doctor ordered the study (although this should be easily obtainable or in your records). [29] This information contained no direct recall of Mr Wootton's presentation at the time of the scan. It only certified that if he had presented with worrying symptoms appropriate action would have been taken, if necessary urgent hospital admission. 30] Dr Young asked for comment from Dr Scott Wells, a specialist neuroradiologist, particularly on the question of how such cases might be handled in future. Dr Wells replied on 28 January 2011: "I would suggest the following guidelines to prevent an event, such as we discussed, in the future: The referrer should be contacted directly and the possibility of acute admission/neurosurgical assessment discussed under the following circumstances: 1. Severe spinal stenosis recent onset. 2. Spinal stenosis with symptoms of spinal cord compromise or cauda equina syndrome 3. Suspicion of discitis. 4. Progressive focal neurological deficit with significant imaging lesion. Note: This might require specifically asking the patient about bladder/bowel symptoms if this is not provided on the request if there is a severe stenosis on imaging, especially if the request was written sometime ago. Severe degenerative spinal stenosis due to disc bulge/facet and ligamentous hypertrophy wouldn't usually require urgent discussion. ie these lesions will usually be due to a large disc protrusion/extrusion or tumor." "31] A point made in this advice was that severe degenerate spinal stenosis does not in itself require urgent discussion and possible hospitalisation. The respondent says that this was the presentation at the time of the scan, that is to say that spinal stenosis and its L3/4 origin was apparent, but not symptoms of cauda equina syndrome. The advice left open the question concerning cases in which a patient should be specifically asked about bladder/bowel symptoms. Dr Young commented, concerning Dr Wells' advice: "So, in terms of whether we could or should have done anything different, it seems to rely on his symptoms and physical signs at the time, whether the stenosis was recent (you will see on the previous scan report that degenerative disc disease was present in 2008), and whether there was progressive clinical deterioration. As I said to Mr Wootton, we frequently arrange for immediate hospital admission for patients with acute illnesses or injuries, so the same would certainly have been arranged for him if it was considered necessary at the time." [32] In this way the question was brought back to whether the appellant's presenting symptoms raised an alarm. [33] The Corporation obtained further advice from specialist neuro-radiologist Dr Moriarty. Dr Moriarty's opinion, as summarised in the respondent's submisions, was that: The scan was reported accurately and appropriately by Dr Oram; . The MRI report was disseminated in a timely fashion; . Back and leg pain are common presenting conditions in patients who undergo lumbar spinal MRI. Large disc extrusions and a degree of spinal canal narrowing are also commonly seen; . Dr Moriarty stated that "there was no indication at the time of the MRI examination that Mr Wootton had symptoms to suggest compression of the cauda equina"; Dr Moriarty concluded "I can find no fault with the way that Christchurch Radiology had handled this case. " 34] Ms Parry-Canet submitted that Dr Moriarty could not state that the appellant did not present with cauda equina symptoms because: . He was not examined or interviewed to clarify whether he was able to stand up properly, There was no detailed information of the extent of the physical examination carried out by the Christchurch radiology group, The bladder issues were not elicited. . The opinion is at odds with the fact that the imaging findings are in keeping with cauda equina syndrome being moderate-severe spinal canal stenosis with displacement of the cauda equina nerve root into the right side of the spinal canal and complete effacement of CSF. [35] The respondent's view is that the bladder issues had not become apparent and there was no reason to alert the radiologist to question the patient about possible bladder issues. The symptoms of spinal cord compression were otherwise normal for a patient with a large L3/4 disc extrusion. However there seemed to have been no explanation of the significance of displacement of the cauda equina nerve roots into the right side of the spinal canal. The appellant quite reasonably wanted to know what the significance of that finding was. [36] Following Dr Moriarty's advice, the Corporation issued its decision declining cover. The decision was accompanied by a treatment injury report summarising the advice received by the Corporation. The opinions of Mr Finnis and Ms Jackson [37] Ms Parry-Canet then wrote to neurosurgeon Mr Nicholas Finnis. Her letter stated that Mr Wootton had excruciating pain in his back and legs when he saw Mr Rietveld on 24 June 2010, and also had a little bit of a bladder and bowel problem. The letter recorded that on 2 July he had severe pain levels and had to be aided by his daughter in the MRI room, that he had difficulty standing up when the radiologist explained the MRI findings, and that he had to be aided out of the room by the radiologist. He then could not drive home because of the pain. 38] Mr Finnis replied on 28 May 2011, basing his advice on the information in the letter and on relevant documents forwarded with the letter. Mr Finnis traversed the information and documentary material thoroughly and answered some specific questions as follows: 1. What are the initial symptoms indicating a possible compression of the cauda equina especially given the MRI findings on 2 July 2010? On review of the accompanying documentation the first definite presentation of the cauda equina compression would have been with the abrupt onset of weakness and sensory loss in the lower legs developing on the evening of 3 July 2010. Associated with this was the inability to void. In retrospect the clinical presentation to Mr John Rietveld with back pain and pain radiating down both legs were most likely related to the disc prolapse with bilateral neurogenic pain radiating into the legs. Given the absence of any neurological features, including normal neurological examination, Mr John Rietveld, not incorrectly, interpreted this as primary and mechanical back pain. Bladder and bowel disturbance is common with back pain and interpretation of this in the presence of other normal neurology would not necessarily lead to a conclusion of cauda equina compression. In conclusion, it is apparent that although he had severe back pain and, indeed, bilateral sciatica likely prior to the MRI scan of 2 July 2010 the specific symptoms of the cauda equina compression were not evident until 3 July 2010. 2. Given the MRI findings of 2 July 2010 and Mr Wooton's [sic]presentation at the time would it be reasonable for medical practitioners to suspect a possible compression of the cauda equina and when (morning of 02/07/10 or afternoon 02/07/10)? The MRI findings of 2 July 2010 showed a large disc prolapse with compression of the cauda equina. Interpretation from this is that this is very likely the cause of Mr Wooton's back pain and pain radiating into his legs. The correlation between the symptoms and the MRI findings is evident and it would be reasonable for any practitioner to make this. Although the MRI scan does show cauda equina compression the important issue is whether the clinical features were strong enough to suggest there was serious compromise to the nerve of the cauda equina. Unfortunately with the presence of back pain and leg pain, even though it is bilateral and severe, the diagnosis cannot be made with certainty. Although, again, in retrospect one can see symptoms not out of keeping with patients with cauda equina compression, these were still not specific at that time and clinical concern about this was reasonably not raised. It was with the development of the neurological symptoms on the subsequent day, 3 July 2010, where the full clinical picture of the cauda equina developed. 3. What is the reasonable and appropriate treatment of a suspected compression of the cauda equina and/or the cauda equina syndrome? It is not uncommon on MRI scans with patients having spinal conditions to show marked narrowing of the central canal and compression of the cauda equina. Management decisions, however, in this situation would be still based on the clinical symptoms. If the cauda equina compression is chronic or over a long period of time then specific symptoms may be absent and in some situations, treatment may not be necessary. With development of the cauda equina syndrome; that is symptoms related to compression of the nerves of the cauda equina, then surgical decompression would be recommended. Once the symptoms have developed then it is generally recommended that treatment; that is surgical decompression, should be performed within 48 hours (Arigo, B.S. et al, 2011). Many studies have examined the question of the necessary time to surgery, and although there are some mixed conclusions, the generally accepted guidelines are that this should be performed on an urgent basis within 48 hours of symptoms (Shapiro, S., 1993; Busse, J.W. et al, 2001; Olivero, W.C. et al, 2009; Gleave, J.R. et al, 1990; Jennett, W. B., 1956; Kostuik, J.P., 1986; Shepard, R. H, 1959; O'Laoire, S.A., 1981; Ahn, U.M. et al, 2000; Qureshi, A., et al 2007; Mccarthy, M.J. et al, 2007; Robinson R. G., 1995; Shapiro, S., 2000; Dinning, T.A. et al. 1993; Delamarther, R. B. et al, 1991.) 4. What is normal time frame for the treatment of compression of the cauda equina? Why? The general recommendations for the treatment of cauda equina syndrome is to perform decompressive surgery within 48 hours. The reason for this is that most studies would show improved outcome following decompression within this time period versus delayed decompression. A meta-analysis of a large number of papers supported this conclusion (Ahn, U.M. et al, 2000). Although timing is important, outcome is also dependant on the severity of the symptoms at presentation (Qureshi, A. et al, 2007). The specific figures for timing of surgery for Christchurch Hospital is not available. Several papers, however, have looked at this; the most recent being a review of times to presentation and surgery and outcomes in California by Robert T Arrigo, 2011. They found that nearly 90% of patients presenting with cauda equina syndrome were operated on within 48 hours of admission. In this group 76.59% was operated on before 24 hours, 12.15% between 24 and 48 hours, and 11.26% were operated on after 48 hours. These figures, however, are better than the paper published by Qureshi in Leicester, UK (Qureshi, A et al, 2007). They found that the 36% of patients were able to be operated on prior to 48 hours of which only 21% were operated on prior to 24 hours. These rates would obviously be influenced by referral patterns, hospital demographics and availability. Following the presentation of cauda equina syndrome Mr Wooton was operated on in an acceptable period of time; that being within 24 hours assuming the symptom onset on the evening of 3 July 2010. His poor outcome is not related to delay of surgery but due to the severity of his presenting symptoms at this time. The available information would suggest that Mr Wooton was treated appropriately following a presentation of his cauda equina syndrome. He appropriately called the ambulance and subsequent treatment from this time was carried out in a timely manner. His poor outcome is related to the severity of the symptoms with presentation very abruptly. Although Mr Wooton obviously had severe symptoms; namely back pain with some leg pain prior to this, which was clearly related to the disc prolapse and demonstrated on 2 July 2010, the clinical picture of a cauda equina compression was not fully evident. The associated symptoms of bilateral leg pain, in retrospect, may be related to the cauda equina compression, however the other symptoms, that being neurological features, were not strongly present to reasonably raise concerns." [39] Mr Finnis did not support the appellant's claim for treatment injury cover. He considered that the poor outcome was related to the severity of his presenting symptoms at this time. Treatment within a recommended period of 48 hours left a considerable margin in this case, between definite symptoms on the evening of 3 July and surgery on the morning of 4 July. The period of 48 hours even accommodated symptoms from the morning of 2 July. Mr Finnis referred to extensive medical literature in support of his opinion. In his answer to the third question he drew a distinction between radiological evidence of compression of the cauda equina and evidence of compression of the nerves of the cauda equina which signals cauda equina syndrome. That opinion answers the question why the information from treating professionals had not identified the radiological evidence of displacement of the cauda equina nerve roots as a critical indication. Mr Finnis advised that diagnosis depends on the clinical evaluation, that is to say the radiology did not represent cauda equina syndrome and the appellant's presentation would have been typical for his L3/4 disc extrusion. [40] An opinion was then obtained from Ms Jackson who had made the treatment injury claim. Ms Jackson's letter is dated 20 April 2012, but there is a date error because it was received before the Reviewer's decision on 5 April 2012. Ms Jackson expressed a strong opinion concerning the diagnostic conclusions that could have been reached by Mr Rietveld on 24 June and by Dr Oram on 2 July. These conclusions are based on symptoms that Ms Jackson did not see but which were derived at least partly from the appellant's own account. Ms Jackson wrote: "Mr Wootton had symptoms of partial cauda equina syndrome on presentation to Mr Rietveld in June 24" 2010 and that would have been the reason why he organised an urgent MRI scan of his lumbar spine. Mr Wootton had low back pain and bilateral leg pain with symptoms of sphincter dysfunction as well as neurological symptoms in his legs. This is a very clear red flag and is an indicator for an urgent MRI scan. The MRI scan was performed urgently on July 2" 2010 and it demonstrated a large L3/4 disc prolapse centrally which virtually obliterated the spinal canal and hence caused severe cauda equina compression. At the MRI suite Mr Wootton exhibited clear cut symptoms and signs of cauda equina compression from his descriptions. They were sufficiently severe that he required assistance to get out of the MRI suite. The Radiographer took the time to show them the MRI and to explain the severity of the changes and provided him with an MRI copy on a disc disc which should have expedited his treatment. There is no doubt from the descriptions which I have been provided with by Mr Wootton that at the time of the MRI scan and at the time of the GP home visit on the afternoon of Friday 2" July 2010 that he had clear symptoms and signs of partial cauda equina syndrome." [41] The view that the appellant exhibited clear symptoms and signs of cauda equina compression at the time of the MRI is contentious. Ms Jackson did not explain precisely what facts she derived from Mr Wootton's own explanation. Dr Oram was not approached at an early enough stage after the surgery for him to recall the occasion, and there is a complete absence of explanation from Dr A. Ms Jackson filled in the gaps, apparently from Mr Wootton's explanation, but it is not at all clear whether he was a reliable historian concerning relevant symptoms, and more importantly whether he brought those symptoms to the attention of Dr Oram or Dr A and in what circumstances. There is no evidence that he was questioned concerning possible sphincter dysfunction, or whether the overt symptoms were such that he should have been questioned. [42] Ms Jackson's opinion was given in reply to a letter from Mr Wootton himself, in which he set out some questions. Ms Jackson continued: "In question 4, the answer is speculative because the only account that we have of how Mr Wootton felt and was presenting has been provided by him. The only indication we have of the seventy of his pain is the fact that his GP made a home visit and injected him with non-steriodal anti-inflammatory medications. Considering his description of how severe his pain was and how it was limiting his mobility at the MRI suite and the fact that he required the GP to attend him at home that day at either juncture I would have thought It would have been prudent to have called an ambulance and send him to the Emergency Department with the CD of his MRI. In any event this is what happened on the night of Saturday, July 3 2010 when he was brought in by ambulance to the Emergency Department at Christchurch Hospital. He was logged in at 0120 hrs on Sunday, 4" July 2010. I examined his pathway through the Emergency Department with Dr Angela Pitchford who is the Clinical Director of the Emergency Department and it appears that the appropriate reviews and referrals took place in a timely fashion from the Emergency Department perspective. He was transferred to the Orthopaedic Unit. It was while he was in the Orthopaedic Unit that he progressed to a virtually complete cauda equina syndrome between 0300 and 0800 hours approximately. It was only at that stage that he was referred to Neurosurgery which was the next appropriate step. Had Mr Wootton received surgery from Mr Rietveld in the private sector or reached Emergency Department on Friday, 2" July 2010 with the level of symptoms he had at that time and had surgery in a timely fashion it is very unlikely that he would have his current level of disability. He had had sphincter dysfunction for several weeks at the time of the scan and it is likely that he would have had some residual problems from this perspective. His motor sensory recovery however should have been significantly better." [43] The letter raised or repeated several concerns that have not been addressed in the investigation, namely the signs and symptoms that should have been apparent to Dr Oram and later on 2 July to Dr A. The review [44] The review was heard by Reviewer Ms N R Coddington on 22 March 2012. The letter from Ms Jackson was obtained after the hearing and was taken into account in the review decision. The review decision contained a very thorough and careful examination of the evidence of symptoms and medical advice. The Reviewer concluded: "I take the medical evidence detailed above to be saying that Mr Wootton did not show symptoms suggestive of cauda equina compression until at the earliest, on 3 July 2010. Neurosurgeon Mr Finnis said the specific symptoms of the cauda equina compression were not evident until then/3 July 2010. Mr Wootton's treating specialist, Ms Jackson said that he progressed to a virtually complete cauda equina syndrome between 0300 and 0800 hours approximately on 4 July 2010, whilst in the Orthopaedic Unit of Christchurch Hospital. Dr Moriarty said there was no indication at the time of the MRI examination on 2 July 2010 that Mr Wootton had symptoms to suggest compression of the cauda equina. Based on Dr Moriarty's advice, I take him as meaning that the 'relative moderate-severe spinal canal stenosis with displacement of the cauda equina nerve roots into the right side of the spinal canal and complete effacement of CSF' reported at the L3/4 level on the MRI scan taken on 2 July 2010, was not indicative or suggestive of actual compression of the cauda equina I find the medical evidence tilts more towards ACC's position in this case. I accept its submission that given Mr Wootton's presenting signs and symptoms on a background of pre-existing leg and back pain it was not feasible for the treating clinicians on 2 July 2010 to refer him acutely to hospital for cauda equina syndrome. The objective specialist medical evidence shows that the compression of the cauda equina had not manifested at that stage (on 2 July 2010). According to Mr Finnis, at the earliest, Mr Wootton did not have symptoms of compression of the cauda equina until 3 July 2010." Submissions [45] Ms Parry-Canet for the appellant submitted that the severity of symptoms on presentation to hospital in the first hours of 4 July 2010 was due to the lack of treatment and failure to diagnose the spinal cord compression in a timely manner and provide further treatment. [46] It was submitted that the fact that the appellant was not properly examined by the CRG does not alter the fact that proper examination and questioning could have enabled a diagnosis of partial cauda equina syndrome and instigated early hospital admission. Ms Parry-Canet submitted that, because the quality of the outcome of a cauda equina decompression depends also on the severity of the symptoms at presentation, it would be prudent for a medical practitioner to refer the patient urgently before the syndrome can be diagnosed with absolutely certainty once all the features are present and before it reaches the severity levels that would impair the quality of the outcome. She submitted that, had the diagnosis of cauda equina syndrome and treatment been made before the early hours of the 4 July 2010, the appellant would have sustained lesser consequential injury, particularly loss of motor function. [47] Ms Parry-Canet submitted that even if some circumstances may have prevented Dr Oram or Dr A from making a diagnosis of cauda equina syndrome to a degree of medical certainty, a proper examination would have enabled a reasonable diagnosis of cauda equina syndrome. Treatment could then have been achieved within the required time frame of 48 hours before the symptoms became too severe. It is submitted that Dr A had the clinical knowledge of Mr Wootton's condition on 2 July 2010 morning as Mr Rietveld had informed her previously about the bladder problems, and she should have had knowledge of the MRI findings. [48] The respondent submits that it was only some later time between 3.00 am and 8.00 am on 4 July 2010, while he was in the Christchurch Hospital Orthopaedic Unit, that the appellant's condition progressed to a complete cauda equina syndrome. Mr Coates submitted that the appellant's own evidence and reports from the CRG were consistent on the point that the radiologist was not informed of symptoms of sphincter dysfunction. I note that the appellant's evidence as to whether he had such symptoms is equivocal. 49] It was submitted that the medical evidence is clear that Mr Wootton did not show symptoms suggestive of cauda equina syndrome until 3 July 2010 at the earliest, and on his own evidence, the bladder and bowel problems 'gradually happened after the 2 July MRI leading up to 5.30 am on 4 July. It was submitted that his presenting signs and symptoms when he attended for the MRI, and again when he was assessed on 2 July by his GP, were not such that it can be said that there was a failure to refer Mr Wootton to hospital for cauda equina syndrome. [50] Mr Coates submitted that the opinion given by Mr Finnis was very thorough in comparison with the letter from Ms Jackson concerning undue delay in admission to hospital. Ms Jackson also acknowledged that the answer concerning the prudent course that should have been followed was speculative because the only account of how the appellant felt and was presenting was provided by him. Mr Coates provided written submissions concerning the judgment of medical questions of causation, referring in particular to ACC v Ambros [2008] 1 NZLR 340 (CA), in which it was said that a court may only draw a valid inference based on facts supported by the evidence and not on the basis of supposition or conjecture. Risk of causation does not suffice. Decision [51] While being reluctant to decide the outcome of this appeal on a different basis from that on which it was argued, I cannot ignore the almost complete absence of evidence from Dr Oram and Dr A, the two medical professionals whom the appellant claims had an opportunity to diagnose partial cauda equina syndrome and arrange early admission. [52] It is probably now too late to obtain any useful information from Dr Oram, who observed at most a patient in distress from pain and mobility problems evidently caused by an L3/4 disc extrusion. Dr Oram made the MRI scan available to the appellant's general practitioner and treating orthopaedic surgeon, but it does not appear that he would have been given any information about bladder problems and there is a leap of logic to suppose that the appellant's severe discomfort at the time of his MRI scan would have given an indication of possible cauda equina involvement dictating a need for hospital admission. [53] The Corporation's decision was issued after Dr Moriarty's advice that CRG were not at fault. He advised the Corporation as a radiology expert and not as a general practice expert, nor did he give any comment on the responsibility of the general practitioner. [54] There is no evidence of any attempt by the Corporation to seek a full account from Dr A. [55] Ms Jackson's opinion is based on presentation of symptoms derived partly from the appellant's own account, but not usefully verified. The medical evidence focuses on loss of bladder function or symptoms of sphincter dysfunction as a critical indicator of cauda equina syndrome. Evidently there is a spectrum of signs and symptoms that would be used in diagnosis of possible onset of cauda equina syndrome. Ms Jackson's view tended to equate reported bladder problems with sphincter dysfunction, or at least to consider that the bladder problems were such that sphincter dysfunction should be suspected. There are also accompanying symptoms such as paraesthesia, on which the evidence is silent. Ms Jackson acknowledged that her opinion had to be based on the appellant's account and was therefore speculative. [56] A decision on whether an injury is not an ordinary consequence of treatment depends on evidence of the ordinary outcome of treatment given in accordance with proper medical practice. While cover for treatment injury is not based on fault, it remains relevant to know whether or not the general practitioner or other treating profession made a critical decision in accordance with a responsible medical standard of practice. The decision may very well depend on the difference between the expected outcome of proper medical practice and an outcome following a treatment decision that did not reach the expected standard. [57] In this case, the claim that the radiologist should have taken a different course of action is refuted by Mr Finnis. The appellant's argument in the appeal is that either the radiologist or the general practitioner should have arranged for hospital admission. The absence of evidence from the general practitioner is crucial and that should have been apparent when the claim was investigated. Although the claim was lodged by Dr A on the basis that the radiologist should have acted differently, there was also a treatment claim form submitted by Ms Jackson claiming in more general terms a delay in recognising the proper diagnosis. [58] I agree with the Reviewer's conclusion that the evidence as it stands leans in favour of the respondent's correct decision declining cover. I find however that there is a strong body of evidence that the respondent failed to investigate the claim. The appellant relies on his own account of the symptoms that he says should have been picked up by Dr A. Ms Jackson's opinion also relies on the appellant's own account. It is very difficult to make an informed judgment of the weight to be given to the appellant's account of his symptoms without reasonably complete information from Dr A. [59] It is unclear why the investigation was closed with Dr Moriarty's advice concerning the responsibility of the radiologist. If comment from Dr A was sought there is no information about that in the evidence as it stands. If it was not sought, then there is possibly a basis for the appeal to be allowed in order for the Corporation to complete an investigation and make a new primary decision. [60] This is a matter on which the parties should be entitled to be heard. Therefore this decision is issued on an interim basis and the parties are invited to make further submissions on the question of proper investigation of the claim. A timetable will be issued if necessary. In the first instance written submissions are invited from the appellant who will have a right of reply. No further oral hearing is envisaged. Judge D A Ongley District Court Judge