Legg v Accident Compensation Corporation

IN THE DISTRICT COURT AT PALMERSTON NORTH [2015] NZACC 263 ACR 112/14 UNDER THE ACCIDENT COMPENSATION ACT 2001 IN THE MATTER OF AN APPEAL UNDER SECTION 149 OF THE ACT BETWEEN STEPHEN JAMES LEGG Appellant AND ACCIDENT COMPENSATION CORPORATION Respondent Hearing: 28 April 2015 Further submissions and evidence: 15 July 2015 Appearances: S J Legg in person O D Tapper, counsel for respondent Judgment: 1 September 2015 RESERVED JUDGMENT OF JUDGE A N MACLEAN Introduction [1] The issue in this appeal is whether the respondent's decision of 14 August 2013 declining funding for an interventional pain management (IPM) injection to deal with lower lumbar pain for the appellant was correct. [2] A review on 23 February 2014 upheld the respondent's decision. 3] In the course of the hearing before me interesting issues arose which reflect the fact that the appellant who is a professor at Massey University, is the co-author of an article published in the journal "Applied Ergonomics - Human Factors in Technology and Society" with the title "Prevalence and Work Related Risk Factors for Reduced Activities and Absentism due to Low Back Symptoms". This scientific background coloured his approach to his own case and mirrored the differing approach to proof and causation discussed in the leading Court of Appeal case of Accident Compensation Corporation v Ambros. The appellant thus in his submissions framed many of his points against a scientific background and also tabled for the Court's consideration not only the article previously mentioned but also the following: "ACC and back injuries the relevance of pre-existing asymptomatic conditions revisited "by the New Zealand Medical Journal authors Peter A Robertson and O Ross Nicholson" - a brief summary of the theme of that article taken from the abstract is "the application of the New Zealand Accident Compensation Corporation legislation in the management of patients who sustain back injuries requires a detailed knowledge of the pathogenesis of tissue injury in the natural history of aging and related conditions so that the application of the ACC Act is appropriate". The abstract goes on to talk about "updated the previous knowledge basis in these fields so as to assist the interpretation of the Act". Amongst other things the article is critical of some aspects of what the authors saw as "over reliance on modern high quality imaging ..." and the essentiality "that the decision making relies ... on quality observational population studies rather than expert opinion that may be generated from skewed referral patterns in a previous practice life". The learned authors opine "the notion that the accident has brought the condition to light and the affects of the accident may now be spent lending to the underlying spondylolysis and spondylolisthesis as being the whole or substantial cause of the symptoms or personal injury has no support from the current observational literature". Another article tabled at the hearing is an article in the British Editorial Society of the Bone and Joint Society August 2013 "do intervertebral disc degenerate before they herniate, or after?" [2008] 1 NZLR 340 At the conclusion of the hearing the matter was adjourned both to give the appellant an opportunity to give a considered response to the respondents submissions but also at the request of the Court to seek further comment from both parties on certain aspects Factual Background [4] The background is set out in the review decision and can be briefly summarised this way: Against a background of lumbar pain dating back to 2005( in association with gardening), on 30 June 2012 the appellant( then aged 60) bent forward and to his left while showering. He stood up and immediately felt uncomfortable and had a pain in the right iliac crest area. On 20 July 2012 he saw a chiropractor, Dr Wong who noted pain in the lower back and some apparent improvement in the lumbar area. On 26 July 2012 the respondent accepted cover for the incident describing the injury as "a right lumbar sprain and right sacroiliac sprain". On 7 March 2013 an x-ray not funded by the respondent reported: Moderate scoliosis of the lumbar spine with concavity to the left and tiny marginal osteophytes ... at L4/5. There is mild disc narrowing at this level ... there is no acute fracture. Mid sclerosis of the facet joints is seen. The soft tissue pattern is unremarkable ... impression moderate degenerative change and scoliosis of the lower lumbar spine. The appellant's general practitioner Dr Crowe noted on 14 March after considering the x-ray: ... moderate severe degenerative changes in L/S this is probably causing nerve root irritation in his leg. I suggest he sees the physio and review with me if he doesn't approve. On 20 July 2013 the appellant had organised an MRI and the radiographer Dr Hugh Roberts noted from that: The L4-5 disc demonstrates loss of height and desiccation with an associated disc bulge in the right paracentral location associated with herniation of disc material. This is impinging particularly on the passing right L5 nerve roots. The L3-4 disc also demonstrates moderately severe loss of height and desiccation and there is associated widespread bulging which is particularly marked in relation to the left neuro exit foramen. The remaining lumbar discs are much better preserved. Impression Spondylotic changes with associated prolapse of disc material at 14-5 on the right hand side impinging on the right L5 nerve roots On 29 July 2013 the appellant consulted Dr Michael Cleary who diagnosed: Right sided L4/5 prolapsed inter vertebral disc with right L5 radicular pain and radiculopathy. A caudal epidural administered by Dr Cleary provided no meaningful relief. On the same day Dr Cleary applied for the IPM procedure which was referred to the respondent's clinical adviser Dr Peter Hunter and orthopaedic surgeon and spinal specialist who commented: MRI 20/7/2013 describes multi-level disc disease and facet joint osteoarthritis. This could not have been caused by a single low velocity movement on 7/7/2012 (sic) the covered injury. There is no causal link to fund IPM or treatment. On 14 August 2013 the respondent declined funding on the basis that the proposed IPM injection was not required to treat the covered injury because it would be treating a pre-existing degenerative condition. This then prompted the review application. At that time the respondent consulted Dr Michael Austen an accident and medical practitioner and a member of the Clinical Advisory Panel. He essentially supported the view of Dr Hunter opining: There is no evidence to support a new and distinct injury - the issue is one of causation of that disc protrusion not a dispute about whether there was an accident event or what the personal injury was. The client has established bony changes of disc disease at L4/5 ... the disc material had been bulging/protruding for many months/years prior to the covered injury in 2012. He also further opined on the issue of the prevalence of disc bulges generally: The prevalence of asymptomatic disc bulge in the population at this age group exceeds 90% and the prevalence of asymptomatic disc protrusions exceed 50%. As such there can be no presumption that any event is the cause of such a bulge or protrusion where the x-ray evidence shows that this client already had disc disease prior to 2012 at L4/5 ... asymptomatic nerve root compression occurs at multiple locations in the human body - of which the lumbar spine is one. He also further concluded that he could see no causal link because the method of accident as described earlier would be "insufficient to cause a traumatic disc protrusion". [5] At the hearing the Court was updated on the factual situation to get the total picture. In the event, it emerges, that despite the respondent declining to fund the operative procedure, Dr Cleary was engaged to carry out the following procedures. Initially an injection to 14/5 area was carried out which resulted in no improvement. On 19 December 2014 a trans foraminal injection (TFI) with corticosteroids was administered in the L5/S1 i.e. a lower level which ameliorated the symptoms of radicular pain. The Case for the Appellant [6] In Dr Cleary's updated report of 4 may 2015 he commented on the relevance of a number of articles. [7] One was Nicolai Bogduk 1994: Anatomy of the Spine under the heading "Anatomy and Biomechanics of the Spine" under the subheading "Lumbar Spine". 8] After pointing to aspects of the article dealing with compression loads exerted on the disc by back muscles, the role of the nucleus pulposus, the mechanism of bending and the annulus fibrosis compression with consequent deformation of the nucleus pulposus he noted the conclusion that" disc herniation requires an antecedent degradation of the nucleus and weakening of the annulus fibrosis". [9] Then dealing with an extract from the same text on lifting, he noted the balancing exercise in engineering terms between flexion and moment exerted by the trunk and the external load being lifted and how as the body stoops forward, several forces exert flexion moments. That the load to be lifted exerts an additional moment whose magnitude is determined by the displacement of a load from the lumbar spine. Also that the risk of injury is greater when lifting is associated with rotatory movements of the trunk as in swinging from left to right while in a stooped position so that adding a twisting movement causes the annulus fibrosis to resist more force and undergo further strain with the possibility at a certain point of the posterolateral annulus to tear. [10] Also by reference to another article "Clinical Evidence of Chemical Radiculopathy" (Curtis Slipman et al) he discussed chemical radiculitis namely an inflammatory condition of the nerve root which can result following rupture of the annulus fibrosis and dissemination of disc fluid along the nerve root sheath. [11] He noted that this was relevant because as well as radicular pain that the appellant has he also has radiculopathy (impaired nerve function) manifesting in leg weakness and resisted extension of the right great toe. [12] He described how those symptoms and signs are due to damage of the right S1 nerve tissue from the chemicals from the "large right paracentral disc bulge impinging on right S1" in the MRI report of 20 October 2014 and "spondylitis changes with associated prolapse of disc material at L4-5 in the right hand side impinging on the right L5 nerve roots" from the MRI report of 20 July 2013 which it appears contained a slight mistake in that what was called the L4/5 disc should have been reported as the L5/S1 disc. He said the point is that both radiologists agree that there is contact between the prolapsing disc and the nerve root on the right. [13] He then noted in the context of the TFI in December that he administered, that a 2010 study in "Pain Medicine 2010 - the Efficacy of Transforaminal Injection of Steroids for the Treatment of Lumbar Radicular Pain" Ghahreman et al that there is an emerging consensus that this procedure has a proven effect, in particular, referring to an editorial in Pain Medicine 2010 "Demystifying Lumbar Transforaminal Epidural Steroid: A Seminal Efficacy Study of Specific Spinal Injection which concluded "in the end this landmark study has vindicated transforaminal steroid injection for lumbar radicular pain as superior to placebo". [14] Responding to another matter raised by the Court as to the site of the December TFI , he tabled x-ray images and a report explaining exactly where he injected the corticosteroid injection (Kenacort - A40) into the right L5/S1 foramen which, he noted resulted, as reported by Mr Love on 27 January 2015, as having "had a dramatic and fairly rapid reduction in the pain in his leg" or as Dr Cleary put it "substantial and sustained relief of ... radicular pain". 15] Against the background of the articles earlier mentioned the appellant systematically worked through the submissions of the respondent taking issue with the proposition that the symptoms eventually alleviated by a successful IPM procedure were due to a pre-existing health condition making, in summary, the following points: On the basis of his own knowledge and based on both the initial evidence adduced at the review hearing, and subsequently, from Dr Cleary the mechanics of the bodily movement which he demonstrated to the Court generated sufficient force to cause injury and specially disc protrusion. A strong temporal link i.e. apart from some earlier lumbar pain previously referred to which he described as "muscular" in origin he had had no radicular pain previously down his right leg and it commenced immediately after the incident in the shower on 30 June 2012. He placed great reliance on the opinion of Dr Cleary and in particular Dr Cleary's rejection of the proposition from CAP in his letter of 16 September 2013 to GP Dr Crowe noting against the undisputed fact of a disc prolapse which the respondent advises attributed to age related changes and submitted that, "ignores the fact that there was an accident with tissue injury ... it must be the case of the impact of the fall that brought about a change." Dr Cleary concluded it this way: I find that merely because the L5 disc may well have been in a degenerative state, does not mean that anything associated with it cannot be the subject of cover, if indeed there has been an incident of trauma which has caused that affected disc to impact on the nerve root thereby causing compression ... this is not the case where it is simply a degenerative disc or a general medical condition that was being sought to be treated by way of the surgery rather it was a specific state of affairs namely the L5 nerve root compression on the left side, that is the side that was the subject of the incident of trauma. The medical condition was not bilateral and therefore I find that is another reason for identifying the condition as being of traumatic origin rather than just a progression of degenerative condition. [16] In an updating report of 4 May Dr Cleary expanded, following a request from the Court, on the December procedure and the surrounding circumstances. [17] He summarised the mechanism involved in the shower incident this way: The action bending forwards and twisting in the shower resulted in a prolapse/herniation of the intervertebral disc between the 5t lumbar and the 1" sacral vertebral bodies, conventionally called the L5/S1 disc. The prolapse/herniation came into contact with the right 1" sacral nerve (S1) and the chemicals contained in the prolapse damaged the S1 nerve root so that Mr Legg experienced radicular pain radiating down his right leg and was found on examination to have weakness of the long extensors of the right great toe. [18] In answering the question "what actually happened?" Dr Cleary noted: The action of bending forward and twisting in the shower as described in the reference below resulted in lumbar disc prolapse/herniation. A normal disc does not prolapse (i.e. as highlighted in the text below from Bogduk's chapter on the anatomy and biomechanics of the spine "disc herniation requires an antecedent degradation of the nucleus and weakening of the annulus fibrosis". As recorded in my initial assessment of Stephen, 18 July 2013, "he has a number of low back pain episodes before and I see your letter gave a record in 2005 when he saw Dr Carter. These LBP's were never associated with leg pain however". This raises the possibility of prior injury to the lumbar discs and subsequent degradation of the nucleus pulposus and weakening of the annulus fibrosis. Having been extruded from the L5/S1 disc on 30/6/2012, the chemicals in the degraded nucleus pulposus caused inflammation of the right S1 nerve and nerve injury resulted. There was leg pain from the injury to the nerve and the function of the nerve was impaired (radiculopathy) so that the weakness of the extension of the right great toe was found. [19] He also updated the situation following the TFI in December 2014 noting that there is still an "unknown" as to where repeating TFI would be of further benefit for activity induce and/or rest pain or whether his pain pattern was not ever going to improve. He noted however that the appellant considered the level of pain he had and continued to have after the TFI is sufficient of an improvement that he can resume his travel plans. The Respondent's View 20] The respondent points to the following contraindicators of the proposition advanced by Dr Cleary including: The appellant's own general practitioner preliminary assessment of moderately severe degenerative disease but more particularly the views as outlined previously of Dr Roberts which, it submits implies that the prolapse disc material is due to an age degenerative condition. Dr Hunter's view as an orthopaedic surgeon with extensive back orthopaedic expertise based on his view of the MRI examination. Dr Austen , who has experience in accident medication and was of the view that the mechanics of injury i.e. what he described as "a low velocity injury" would generate insufficient force to cause a traumatic disc protrusion against a general statistical population background of the percentage of asymptomatic disc bulging. [21] There was further medical comment from the respondent in response acknowledging the additional literature referred to and in particular the fundamental statement from Dr Bogduk: Disc herniation requires an antecedent degradation of the nucleus and weakening of the annulus fibrosis And Dr Hunter commented in respect to that: In other words there is gradual process disc degeneration before a disc protrusion can occur. On this occasion bending in the shower may have caused an already abnormal disc to have a protrusion. It should also be kept in mind that recent studies also show that 60-80% of asymptomatic people in their 60s will have signs of degeneration and protrusions in the lumbar spine (Brinjikji et al American Journal of Neurology 27/12/2014). [22] In answer to the question posed: Whether and to what extent the Cleary report shows that disc herniation was caused by the shower accident and was not caused by a pre-existing degenerative condition (whether or not asymptomatic) he said: It is widely accepted by health professionals that a disc annulus is weakened by non trauma disc disease to allow protrusion of the disc nucleus (see Dr Bogduk's work). Bending in a shower could not possibly damage a normal disc not already subject to a pre-existing degenerative condition". [23] In response to a further question: By way of background, Mr Legg stated that the first injection was performed at the wrong lumbar level, when it should have been performed at a slightly lower level. He also submits that there is no evidence that degenerative changes (if any) occurred at a specific location in his spine". He said: The actual pain generator is always elusive to identify and the two MRI reports unequivocally describe what is known by all health professionals as degenerative disc disease. In effect this is acceleration of the normal changes in disc structure that occur between infancy and old age. [24] Commenting on the article referred to at the hearing , Dr Hunter noted: The Robertson et al article largely stems from an article published in 2000 by the same authors (NZ Medical Journal 2000 January 28). The 2000 article is widely accepted in the medical community and covers the picture of lumbar disc pathology well. The conclusions reached in the 2000 article note that it is important not to look at MRI imagery in isolation, but to correlate clinical findings in the patient's medical history (including how the patient has presented and what the patient's symptoms are) with MRI imaging studies when planning treatment. In terms of comparable articles in international medical literature (which may support/contradict the findings in the Robertson et al article) in light of the unique ACC regime in New Zealand there is not a lot on the subject of actual causation of disc herniation. In the present instance this article does not alter my view that the bending over in the shower could not possibly have damaged a normal disc that was not already subject to pre-existing degenerative condition. Analysis and Discussion [25] The case of Manning v Accident Compensation Corporation' helpfully sets out the legal test in this sort of case. That was a case where in the context of the proposition that a bowling injury could have caused two discs to prolapse where there was opposing specialist opinion as to whether osteoarthritis must have predated the injury i.e. generally a substantially degenerative condition, coupled with the rapid onset of symptoms in the context of a disc protrusion, Judge Ongley noted: The legal test allows for a distinction between cases in which a claimant has a predisposing degenerative condition followed by actual injury in cases where a degenerative condition is aggravated by trauma. [26] The proposition being advanced in that case for that appellant was that while there was underlying degeneration, the point of the appellant's case was that some significant but not necessarily severe damage was caused by the accident. [27] His Honour concluded, that on balance the change was more than a mere aggravation of an underlying condition and the existing degenerative condition without which the injury would not have occurred was nevertheless not the whole or substantial cause of the pathology requiring surgery. 28] The appellant repeated in his final reply submissions that he had made at the hearing as to how from his perspective as a scientist he was concerned that the way Courts approach issues such as those arising in this case. As he put it: It worries me that Courts appear to commonly accept expert opinion as a high form of evidence, yet in current scientific/medical disciplines, the strongest 2 [2012] NZACC 166 form of evidence determined by a hierarchy that considers expert opinion as the lowest form of evidence. And contrasting that with the scientific/medical approach endeavours to determine proof (the truth) through a systematic evaluation of a multiplicity of objective studies ... [29] The ground rules for judicial determination of proof/causative links, or absence thereof, are set out in the Court of Appeal case of Accident Compensation Corporation v Ambros' which, as the head note states: The legal burden to prove causation in accident compensation cases remained with the claimant and did not shift to the Corporation. However robust inferences should be drawn in individual cases if sufficient material proof pointed to proof of causation on the balance of probabilities: statistical evidence could be useful as to causation, subject to the limitations of such evidence (for example statistics as to patients in similar situations were not necessarily a guide to what happened in the case at hand); and the relevance of the proximity of medical treatment in injury dependent on the circumstances of the case. [30] In Ambros the Court further observed that: The Court may only draw a valid inference based on facts supported by the evidence and not on the basis of supposition or conjecture. And: There must be sufficient material pointing to proof of causation on the balance of probabilities for the Court to draw even a robust inference on causation. Risk of causation does not suffice. [2008] 1 NZLR 340 [31] The Court needs to determine as it was explained in Johnson v Accident Compensation Corporation: The issue is not whether an accident caused the incapacity. The issue is whether the accident caused a physical injury that is presently causing or contributing to the incapacity. [32] This Court is required to have a rational basis for preferring one expert view to another. 33] On the one hand there is the evidence of Dr Crowe who considered that there was moderately severe degenerative disease likely to be irritating the nerve roots, and Dr Roberts, who noted "Spondylitis changes with associated prolapse of disc material", and Dr Hunter, who has explained why he is firmly of the view that there was insufficient force in the mechanics of what happened in the shower to amount to a traumatic cause and that the disc herniation had been caused by a degenerative condition. [34] Dr Austen supported that view. [35] Then there is the evidence of Dr Legg himself who has gone to a lot of trouble to provide background generalised research and with a background in ergonomics also supported his own case. [36] Two cases that Dr Legg made reference to: namely Leckie, and Lyth can be distinguished in terms of the mechanism of the accident. In Lyth a fall of three metres off a ladder and in Leckie a fall from a boat can be contrasted with a low velocity twisting motion as described in the present case. [37] Apart from Dr Cleary's specialist evidence there is no other objective outside specialist evidence to support the proposition that the disc herniation was caused by the shower incident. High Court Wellington CIV 2010-485-424 [2011] NZACC 89 [2010] 198 [38] On weighing up all the conflicting opinion I am persuaded by the logic and analysis of the specialist opinion provided by the respondent and bearing in mind where the onus of proof lies, am of the view that the symptoms and necessity for treatment are substantially due to a pre-existing degenerative condition that was rendered symptomatic. While the articles referred to are of interest as background they are not determinative and as Ambros requires it is ultimately a weighing up of the expert evidence which is determinative. [39] Accordingly the appeal is dismissed. There is no issue as to costs. Cal Judge A N MacLean District Court Judge ACR 112-14-Legg.doc(aw)