ACCIDENT COMPENSATION - Appeal - Serious injury - Where difference of opinion between expert witnesses as to whether employment was a cause of the appellant's injury - Whether judge at first instance failed to have regard to the evidence of one expert witness - Whether judge at first instance erred in giving greater weight to the evidence of expert witnesses who gave oral evidence - Whether judge at first instance gave adequate reasons - Appeal dismissed.

1 I have had the benefit of reading in draft form the reasons for judgment of Osborn JA. I agree with his Honour, for the reasons that he gives, that the appeal should be dismissed.

2 This is an appeal against the decision of her Honour Judge Kings that a condition from which the respondent ('plaintiff') suffers constituted a serious injury within the meaning of s 134AB(2) of the Accident Compensation Act 1985 ('the Act') arising out, or in the course of, or due to the nature of her employment.[1]

3 The case is an unusual one because first there is no dispute that the condition of cervical dystonia which is in issue (constituted by compulsive spasm and jerking of the neck) itself constitutes a serious injury in the relevant sense. Rather, the primary dispute is whether her Honour erred in the reasons she gave for concluding that a cause of the plaintiff's condition was her employment. Secondly, the case is unusual because the condition in issue is itself unusual and there is a division of expert opinion as to the provable mechanism of its causation.

4 For the reasons I shall set out, I am ultimately of the opinion that in circumstances where the evidence did not exclude other possibilities, her Honour was nevertheless, for the reasons she gave, entitled to prefer the opinion of those medical experts who expressed the view that a causal link between the plaintiff's employment and the condition from which she suffered had been established on the balance of probabilities.

6 Between 1997 and 2008 the plaintiff worked for the first appellant (the employer) as a laundry process worker. She was employed in the area of the laundry where linen bed sheets, table cloths, towels and serviettes were ironed, folded and packed. Her job required her to work as part of a team of employees who fed these items into various machines that ironed and folded them; collected the linen items dispensed from the machines and placed them onto a table or into a basket; and took wet linen items from a table, shook them out and then placed them onto another table so that they were ready to be fed into a machine. The plaintiff's evidence was that these duties were consistent, fast-paced and repetitive, and that they involved her bending and flexing her neck for extended periods of time.

7 From about 2005 the plaintiff began to notice pain in her left shoulder when she was performing these duties. She also began to experience spasms in her neck that caused her to turn involuntarily to the right. In late 2007 the pain and spasms were continuing to increase and in January 2008 they reached a point where the plaintiff took leave from work because she could no longer cope with her symptoms. She has not returned to work since that time.

8 In December 2010 the plaintiff sought leave in the County Court to commence common law proceedings against her employer pursuant to s 134AB(16)(b) of the Act. The application was heard over three days in August 2012, and in December 2012 the trial judge granted the application, giving reasons for her decision and making consequential orders.

9 At the trial the plaintiff was not cross-examined with respect to her affidavit evidence and the trial judge was confronted with a division of medical opinion. The plaintiff principally relied upon medical reports from:

10 Medical reports were tendered from each of these experts and in addition Dr Evans and Professor Cook were called to give oral evidence and cross-examined extensively.

11 The appellants tendered reports from the following experts:

(a) Dr Clayton Thomas (treating consultant in rehabilitation and pain medicine);

(e) Professor Robert Helme (consultant neurologist).

12 In addition Professor White gave oral evidence at the hearing.

13 Both at the outset and conclusion of her reasons her Honour correctly identified the fundamental issue in this case as being whether the plaintiff's employment was a cause of her condition.[2]

14 After identifying this issue she summarised the evidence before her. In order to resolve this appeal it is necessary to take the same course.

15 The plaintiff's case was put primarily in reliance upon the opinion of Dr Evans. Dr Evans had been the plaintiff's treating neurologist since 2008. In the course of his treatment of her he formed the view that the plaintiff's condition was causally related to her work. Central to this conclusion was his observation of repetitive movements which were mimicked by the plaintiff's disability:

Vica (the plaintiff) had been very consistent in her reports of this particular problem even when I saw her and subsequent [sic], that [there] were specific sorts of tasks which involved repetitive movements using the head in a way that mimicked the torticollis (twisting of the neck) that came through with each consultation ...

16 Ultimately Dr Evans based his diagnosis in substantial part upon his clinical experience including the fact that he had personally had at least 36 patients who suffered from dystopic movements that evolved from repetitive work practices. In the course of his evidence he further stated:

Typically what sort of activities in your experience in the workplace can lead to the sort of cervical dystonia that is present in this case?---Firstly, the dystonia is different in different occupations, so in musicians it's involving the limbs. In people who write frequently, it's a writer's cramp or a task-specific dystonia involving the hands. In fact, I've seen a court reporter with this in the past. I have had patients who have dystonia in other body parts, again related to their specific activity, but in the neck I have at least three that I can think of easily, and one patient I recall developed a dystonia that looked like this, with the head - - -

For the transcript perhaps I can indicate that you are indicating leaning to the left-hand side with your head leaning towards your left shoulder?---Yes, the head twisted to the left, flexed to the left, and I asked her what she did and she said, 'Oh, I used to have to answer the phone and I'd put it in my ear like that and input data on the computer or write it down with my hands.' And subsequently she's developed a clear-cut telephonist's dystonia of the neck, and there are other examples like that as well.

One of those reporting in this case is Dr Hjorth. Are you familiar with Dr Hjorth?---I know Dr Hjorth extremely well.

Does he also have a recognised speciality?---He is recognised as a movement disorder specialist and has probably the most experience of any movement disorder specialist in Victoria, possibly Australia, currently practising.

Dr Hjorth describes a case in his experience of a bus conductor who would frequently turn to the left to take fares and issue tickets developing a dystonia related to that movement. Is that the sort of occupational dystonia which you also see on frequent occasions?---Yes, and I've had a weed sprayer who had a similar thing in the past.

17 In explaining his opinion Dr Evans expressly acknowledged that it is quite possible that the plaintiff's condition is idiopathic. In a report of 2010 which her Honour quoted in her reasons, Dr Evans put it this way:

On [the] balance of probabilities, I think that there is sufficient evidence to suggest that this was a peripherally induced dystonia, ie a dystonic posturing that arose out of or from the repetitive nature of her employment that required repetitive and stereotyped movements of her head and neck.

...

In this particular instance, it is possible that the dystonia encountered in Mrs Mircevic's case is a primary or idiopathic dystonia and is idiopathic or unrelated to the nature of the employment. However, I consider that the employment has at least contributed in part or possibly in full. Idiopathic cervical dystonia is uncommon with a prevalence of approximately nine per one hundred thousand. The pattern of dystonia seen in Mrs Vica Mircevic is an uncommon pattern. ... The pattern of the dystonia also tends to coincide with the pattern of neck movements that she was required to make on an ongoing basis during her employment with Alsco Pty Ltd.[3]

18 In the course of cross-examination Dr Evans acknowledged each of the critical circumstances that were put to him supporting the possibility that the dystonia is idiopathic. Her Honour summarised this cross-examination as follows:

• 'idiopathic' meant an unclear etiology but there are potential individual factors which can lead to an increased risk of dystonia;
• cervical dystonia is uncommon; idiopathic cervical dystonia was the most common of the cervical dystonias;
• an idiopathic dystonia is more likely to develop in adulthood;
• at the plaintiff's age, it is more common that you do not find a cause;
• in January 2009, he recognised the non-focal nature of the dystonia; that is, it involved more than one body part;
• on the balance of probabilities, he regarded the plaintiff's condition as a complex task-specific cervical dystonia; that is, where the dystonia overflows into other tasks, as distinct from a task-specific dystonia which is only specific to the task;
• it was the plaintiff's bending and extension of the neck that the plaintiff specifically described to him that aggravated her condition over the years;
• he took into account the posture she adopted at work;
• he said there were two aspects to the posture, the physical adoption of the posture and the sensory contribution; that is, the pain and discomfort the plaintiff described when in the posture, which is consistent with a task specific dystonia;
• in the initial stages with occupational dystonia, the pain is relieved when the posture adopted is stopped, but the condition progresses to become painful all the time;
• he saw twenty to thirty people a week who were suffering from dystonia and he treated five a week who suffered from cervical dystonia;
• he agreed that the majority of patients who present with cervical dystonia did not have a causal link with employment;
• the plaintiff demonstrated having to lift her head back, and slightly tilted forwards, but extending backwards type of motion;
• the work that the plaintiff described was constant work, daily and multiple times per day;
• he said he equivocated on the question of causation;
• usually cervical dystonia deteriorates over somewhere between two to five years, with or without aggravating factors;
• after viewing a DVD taken in April 2008, his view was unchanged about the repetitive nature of the plaintiff's employment and his opinion as to the cause of the injury;
• the repetitiveness of the extension movements of the neck in the first and third videos were not particularly vigorous or forceful, but involved alternating between looking down and looking up. He said he is not impressed by whether movement is forced: the levels of concentration and the fine motor control or fine motor function were relevant.[4]

19 Her Honour further noted that in re-examination Dr Evans said:

• if the dystonia was idiopathic in origin, the kind of work the plaintiff performed could have aggravated the condition;

• he sees one or two patients a week where he can attribute a cause.[5]

20 Mr Hjorth, consultant neurologist, prepared reports relating to the plaintiff in October 2010 and May 2012. In his first report he stated in part:

1. This is Cervical Dystonia. The old term used to be Spasmodic Torticollis.
2. The cause of Cervical Dystonia is often unclear. Sometimes it can be a small part of a generalised dystonia but such cases are rare and do not apply in Vica's case. Sometimes it can occur as a complication of psychotrophic drugs (major tranquillisers and antidepressants). This does not appear to apply here.
3. However you do see Cervical Dystonia occurring as a result of an injury to the neck or the shoulder and you also see it occurring in a situation where the person has to adopt a fixed or stressful neck posture as part of their work. I believe this applies to Vica.
4. For some 15 years I was in charge of the Botox Clinic at the RMH and I also saw a number of patients in private practice. Over that time I would have injected dozens of cases of Cervical Dystonia with Botox. I have seen several cases where the Cervical Dystonia appeared to be caused by the work posture and activities and I believe that to be the case here.

1. As I mentioned in my previous report, I have seen many cases of this condition over many years. A small number of them have a relationship to work. This can be as a result of trauma such as whiplash injury or it can be the result of sustained abnormal posture. I remember one bus conductor who always turned his head to the left to take the money and give tickets to the passengers and ended up after several years with cervical dystonia because of his head turning to the left. There have been many other cases that I have seen.
2. Now the DVD shows people working. Presumably this is at the same work that Mrs Mircevic did and the postures are not all that extreme but I still think that this would have contributed to her developing this condition.
3. It's almost impossible to prove in one particular case that something like this is caused by abnormal posture or by trauma etc. All one can say is that experience suggests that this happens and that the kind of work and posture that Mrs Mircevic was doing has sometimes/often been responsible for this condition.
4. If you leave cervical dystonia for the moment and look at dystonia in the arms for instance, then, it's not uncommon for it to develop with repetitive activity and particular postures. As Professor Helme points out this is common in musicians but you also see it in people who do writing (Writer's Cramp) and typists and so on.
5. On balance, then, it seems probable that Mrs Mircevic's cervical dystonia has been caused, at least, in part, by her repetitive work.

22 Professor Cook, a neurologist, saw the plaintiff for medico-legal purposes on 15 November 2011. In his opinion on the balance of probabilities the plaintiff's employment was the cause of the development of cervical dystonia. He said dystonias are a complex group of neurological symptoms and the cause of these conditions is unknown. Some are related to medications or unknown genetic defect while others may develop in relation to a repetitive task. This is best recognised in conditions such as task specific dystonias that affect musicians.

23 Her Honour summarised Professor Cook's evidence in cross-examination as follows:

• it is often the case that the condition evolves so that other regions might become involved and symptoms might become more severe, even when one has ceased doing the apparent aggravating activity;
• even if a plaintiff is suffering idiopathic cervical dystonia, the probabilities are that the condition would progress;
• the majority of dystonias have not been associated with a particular activity, but those that have been typically develop in the context of a repetitive activity; for instance, playing a musical instrument;
• the bulk of dystonias have no known cause in terms of physical activity and the plaintiff could fall into that category;
• musicians are a category where a pattern has built up because of the numbers that have developed dystonias;
• he thought the plaintiff's repetitive folding and turning may have been a triggering factor;
• he thought it is likely that the repetitive nature of the tasks is relevant, given that he had seen it in other circumstances; that is, musicians;
• a person with cervical dystonia, whether it is aggravated or not by further movement of the cervical spine, was likely to get worse in any event;
• it could just be a coincidence that she was involved in her work and developed the condition;
• it was impossible to dismiss that the work triggered the condition.[6]

24 Ultimately, as her Honour found, the dispute between the parties centred on the difference between the opinions of Dr Evans, Mr Hjorth and Professor Cook on the one hand and Professor White and Professor Helme on the other. Before turning to the evidence of Professor White and Professor Helme it is necessary to record, as did her Honour, that the appellant also tendered reports from Drs Freilich, Poon and Thomas, who had treated the plaintiff at various points in time.

25 Dr Freilich, neurologist, saw the plaintiff on referral from the plaintiff's general practitioner in March 2006. The plaintiff presented with spasmodic torticollis. He referred her to Dr Poon for treatment with injections of Botox. In his view the plaintiff's pain was unrelated to her employment.

26 Dr Poon, neurologist, treated the plaintiff from May 2006 to October 2008. In his view the plaintiff's cervical dystonia did not appear to be work related. He said cervical dystonia will worsen with any form of stress, whether this be emotional, physical, at home or work. He said the plaintiff's condition had worsened to the extent that she was struggling to finish her work, but her workplace was unlikely to have caused or worsened her cervical dystonia.

27 Dr Clayton Thomas, a rehabilitation and pain management specialist, treated the plaintiff on one occasion in February 2008. In his view the dystonia was not work related.

28 Professor White, neurologist, provided reports in March, April and May 2008 and October 2009 to the employer's insurer. In his first two reports Professor White said the plaintiff had an underlying tendency to the development of dystonia and that there was evidence in the medical literature to suggest that rapid repetitive movements can aggravate and precipitate dystonia in those people who are predisposed to it. He accepted that the plaintiff's workplace fitted the criteria for activities that might precipitate dystonia but said it was unlikely that her work was the only contributing factor. He believed the plaintiff's underlying tendency to the development of dystonia had been aggravated by the nature of the plaintiff's repetitive work.

It seemed quite likely that it was not so much the weight of the sheets that she was manipulating that contributed to her condition, but it was the frequency and repetitive nature of the duties that would have contributed. On that basis, I would have to say that I believe her work duties have been a significant contributing factor to the development of her dystonia.[7]

30 In May 2008 Professor White reviewed correspondence from Dr Freilich and reiterated his previous opinion.

31 In October 2009 however Professor White shifted his position after a review of medical literature relating to cervical dystonia.

In brief, cervical dystonia is considered largely constitutional and the only reported case where distinct activity was identified as a cause was in substantially unusual circumstances in a double upper limb amputee who learnt to write holding a brush in his mouth.

Nonetheless, there are reports of cervical and shoulder region dystonias developing after trauma and I have personally been involved in a case wherein a patient developed severe dystonia after prlonger [scil after prolonged] right shoulder region pain and development of a protective but unproductive posture.[8]

32 Professor White said that he believed the major contribution to the plaintiff's disability was constitutional. He was not convinced that work had contributed but it was possible that it had.

33 Her Honour summarised Professor White's cross-examination as follows:

• it was potentially significant that Dr Poon reported the plaintiff had developed uncontrollable head rotation towards the right with associated hypertrophy of the left sternocleidomastoid (around the jaw), which correlated to the movements the plaintiff described she performed at work.;
• the plaintiff's work fits the criteria for activities that might precipitate dystonia; however, reported cases involved complex fine motor movements and not proximal muscles, as is the case of the plaintiff;
• he could not exclude the possibility that there is a significant work contribution;
• his initial opinion was that the work may be contributing and, on balance, he has moved very slightly from that position. He now says he cannot exclude the possibility that there is a significant work contribution;
• he changed his view as a result of the literature research and his own research into motor control.[9]

34 Her Honour further noted that in re-examination Professor White elaborated his opinion saying:

• the facial dystonia was an independent dystonia to the cervical dystonia; they are separate syndromes;
• the two dystonias developed around the same time and on that basis, he thought it more likely that there was an underlying constitutional component to both;
• this does not rule out the possibility that work had aggravated the cervical dystonia, but that would be purely speculative.[10]

35 Professor Helme, consultant neurologist, saw the plaintiff for medico-legal purposes in October 2010 and December 2011. He expressed the view that the plaintiff exhibited typical features of cervical dystonia also known as spasmodic torticollis. He said some forms of focal dystonia such as occupational cramps (for example, writer's cramp and musician's cramp) have been associated with repetitive movements. In his opinion the cause of the plaintiff's condition is unknown and is therefore classified as idiopathic. In his report of 23 November 2010 he succinctly summarised the reasons for this opinion:

In my opinion the cause of the condition in this case is unknown, the so called idiopathic category. My reasons are as follows;

a) the idiopathic group is by far the largest category in this age group.

1. the time course and clinical description in this case match that described for the idiopathic category.

1. there was no specific injury or infection and no other neurologic diseased has become apparent over the five years of observation in this case.

1. repetitive movements have not been identified as a cause of cervical dystonia as opposed to the occupational cramp conditions. The repetitive movement group are noted for extremes of movement in very high level performance scenarios such as seen in musicians as noted above. This worker was involved in several different repetitive movements at different work stations quite unlike this category.
2. the abnormal movements in this case have spread to involve muscle groups that do not parallel the movement described by the worker. This includes head and neck extension as well as facial twitching and limited tongue movement (both observed on examination), and blepharospasm and swallowing impairment (both described by the worker) consistent with the possible development of facial dystonia, and extrapyramidal symptoms and signs in the left arm.

36 Professor Helme undertook a further literature assessment prior to his report of December 2011 and confirmed his view that the cause of the condition in this case is unknown.

37 In February 2012 he viewed a DVD of work duties which he was instructed were similar to those performed by the worker and again confirmed his opinion that the cause of the cervical dystonia was unknown.

38 On 6 February 2012 Professor Helme provided a supplementary report responding to the views expressed by Dr Hjorth. He stated that there was no credible literature supporting the postulated link between repetitive work and cervical dystonia. Nevertheless other focal dystonias have been recognised to be strongly related to prolonged posture and repetitive motor performance such as may be seen for example in the hands of professional musicians. He could not discount the possibility that this mechanism might also apply to cervical dystonias but considered it most unlikely given the lack of evidence in the medical literature. He also stated that if the video of working conditions with which he had previously been supplied was truly representative of the work done by the plaintiff then in his opinion the degree of sustained or repetitive activity was insufficient to cause cervical dystonia even if such a relationship existed.

39 In July 2012 he viewed a further two DVDs and again confirmed his opinion.

40 It can be seen that Professor White changed his opinion concerning a causal link between the plaintiff's employment and her neck condition because a survey of the medical literature which he undertook did not establish that a clear causal link had been scientifically established between such activities and cervical dystonia.

41 Likewise Professor Helme's view was fundamentally founded on the lack of evidence in the medical literature for a link of the type postulated.

42 Conversely the plaintiff's doctors took the position that although for the reasons identified on behalf of the appellants in cross-examination it was possible the plaintiff's dystonia was idiopathic, their clinical experience led them to believe that it was more probable than not that the plaintiff's injury was work related.

1. What was in issue in this case was whether the plaintiff's cervical dystonia was caused by or related to repetitive movements she performed in the course of her employment. The evidence was that the causes of cervical dystonia are unclear and there is differing medical opinion on the subject.
2. Whilst a considerable amount of material was placed before me, essentially the dispute between the parties centres on the apparent differences between the opinions expressed by Dr Evans, Mr Hjorth and Professor Cook, and those of Associate Professor White and Professor Helme.
3. I heard oral evidence from Dr Evans, Professor Cook and Associate Professor White and I was greatly impressed by their learning and experience in the field of diagnosing and treating neurological disorders. They were undoubtedly qualified to give expert evidence about this medical condition. They did their best to answer the questions that were put to them. At times this was complicated by the differences in the meaning of words in a legal, rather than medical, context. They did their best to assist me in determining the cause of the plaintiff's injury.
4. The difference between the opinions was slight. On the one hand, the opinion of Dr Evans was that it was possible that the plaintiff's dystonia was idiopathic and unrelated to the nature of her employment, but he thought her employment had probably contributed to or aggravated her injury. Professor Cook's opinion was that even if the plaintiff's dystonia was idiopathic, working on for a number of years would at least have aggravated the condition. On the other hand, the opinion of Associate Professor White was that her injury was largely constitutional but he could not exclude the possibility that work had contributed to the injury. All witnesses accepted that the majority of cervical dystonias are idiopathic; that is, they occur spontaneously without any external cause.
5. Dr Evans was impressed by the level of concentration and the fine motor control or fine motor function of the movements the plaintiff performed at work, that the work was constant work, daily and multiple times per day and that the pattern of the plaintiff's dystonia tended to coincide with the pattern of neck movements that she made during her employment. Dr Evans agreed that the area is controversial within the medical profession and there is merit in the opposing view. His opinion was consistent with those of Professor Cook and Mr Hjorth.
6. Associate Professor White, on the other hand, was mindful of the medical literature on dystonias, in particular that while the plaintiff's work fits the criteria for activities that might precipitate dystonia, reported cases involved complex fine motor movement and not proximal muscles, as in the case of the plaintiff, and that the only reported case where distinct activity was identified as a cause of cervical dystonia was in a double upper limb amputee who wrote holding a brush in his mouth. Associate Professor White's opinion was consistent with the opinion of Professor Helme.
7. In considering whether the plaintiff's employment was a cause of her injury, I place greater weight on the evidence of the medical witnesses whose opinion was tested in Court. In particular, I am persuaded, on the balance of probabilities, by the evidence of Dr Evans. First, he has treated the plaintiff for in excess of four years. He is an acknowledged expert in movement disorders and leads the Movement Disorders Service at The Royal Melbourne Hospital. His evidence was supported by Professor Cook. Both witnesses gave evidence to the Court. Their evidence was supported by Mr Hjorth, neurologist. I accept that Dr Evans said he equivocated on whether the injury was work related, but overall considered her injury was related to her work.
8. I accept that Dr Freilich and Dr Poon, both neurologists, and Dr Thomas, do not accept work is a cause of the injury. I place less weight on their evidence because it was not tested in Court. In addition:

• Dr Freilich's expertise in cervical dystonia did not extend to treatment of the condition. He saw the plaintiff on one occasion.
• Dr Poon's reasoning was unsatisfactory. He said the condition will worsen with stress - physical or emotional, at home or work. He said the plaintiff's condition has worsened, to the extent she struggled to finish her work, yet he concluded her workplace was unlikely to have caused or worsened her position.
• Dr Thomas' speciality is rehabilitation and pain management, not movement disorders.

1. Given all the evidence, I am satisfied that the plaintiff has suffered a compensable injury under s5 of the Act. I am satisfied, on the balance of probabilities, that employment has been a cause of the plaintiff's injury.[11]

The primary judge failed to make relevant findings on material questions of fact and therefore did not give the detailed reasons required by s 134AE of the Accident Compensation Act 1985 ('the Act'). In particular -

(a) the primary judge did not consider and evaluate the evidence of Professor Robert Helme; and

(b) the primary judge did not address and make necessary findings as to whether the plaintiffs injury was an aggravation of a condition that was unrelated to the plaintiff's employment with the first defendant and, if so, whether the aggravation was a 'serious injury' for the purposes of s 134AB of the Act.

45 Ground 1 of appeal is directed towards the adequacy of her Honour's reasons. It is not contended her Honour was plainly wrong as a matter of fact.[12] As the ground was developed in argument it was contended that:

(a) her Honour failed to address the logic supporting the opinion of the appellants' experts; and

(b) her Honour failed to specify whether the plaintiff's injury was an aggravation of a condition unrelated to employment and if so whether the aggravation was itself a serious injury in a necessary sense.

46 There is a preliminary question raised by the terms of ground 1. Section 134AE of the Act provided at the date of hearing as follows:

134AE Giving of reasons

The reasons given by the court in deciding an application under section 134AB(16)(b) shall not be summary reasons but shall be detailed reasons which are as extensive and complete as the court would give on the trial of an action.

47 This section has since been repealed. If the matter was remitted for rehearing, as the appellants contend it should be, the judge would not be obliged to comply with s 134AE on the rehearing by reason of the terms of the relevant transitional section.[13] In turn, remission essentially for the purpose of enforcing the obligation which fell on her Honour to comply with s 134AE would be essentially futile. This point was raised by the Court. It had not been addressed in written submissions. That said, both parties were ready to respond to the point.

48 Senior counsel for the appellants submitted that independently of s 134AE the trial judge was, and any future trial judge would be, under an obligation to provide reasons which:

(a) dealt with the substantial points raised between the parties; and

(b) revealed an intelligible path of reasoning.[14]

49 Counsel for the respondent did not contest this submission but positively asserted that the obligation to provide reasons remains full and comprehensive because the common law obligation to give reasons is revived.

50 The ramifications of the repeal of the section were not in my view fully considered and argued. It is a point of potential significance. This is not a case in which it is appropriate or necessary to evaluate the effect of the repeal of s 134AE, save to observe that it is difficult to accept that it was purposeless and of no effect.

51 Nevertheless I accept that her Honour was under the obligations identified by senior counsel for the appellants and further that those core obligations would persist upon a rehearing if such were necessary in the present case.

52 This said, it seems to me that the second requirement postulated was plainly met by her Honour. After analysing the evidence she stated reasons for preferring the opinion of Dr Evans. Whatever criticism might be made of the correctness of that reasoning, the path of her reasoning was clear.

53 The main thrust of the argument put on behalf of the appellants was however as I have said directed to the adequacy of her Honour's reasons for rejecting the opinions relied on the appellants.

54 The fundamental difficulty confronting the appellants is that the plaintiff's experts conceded that it was quite possible the plaintiff's dystonia was idiopathic. Further, they conceded the circumstances put to them in cross-examination supporting this view. The critical question was then whether it was open to her Honour to prefer the opinions which were expressed in favour of the postulated causal link on the basis of clinical experience. The scientific knowledge revealed by surveys of the medical literature did not logically preclude such a conclusion. As Professor Cook said it is a difficult task to assess case history evidence with respect to a rare condition. Nor did a decision reached on this basis fail to grapple with the logic of the appellants' case. That logic established what the plaintiff's doctors conceded, namely that it was quite possible there was no relevant causal link. In order to proceed past this point the plaintiff's case depended upon the opinions expressed by reference to clinical experience. In my opinion, it was open to her Honour to reach the conclusion she did for the reasons she stated.

55 First, there is, as her Honour noted, a difference between scientific and legal language and concepts. In particular evidence which does not permit clear scientific proof of causation may still permit a judgment as to causation made on the evidence before a Court as to the balance of probabilities.

56 Second, her Honour was entitled to regard each of the matters on which she based her preference for the opinion of Dr Evans as relevant. First, the fact that he had treated the plaintiff for in excess of four years was relevant because his opinion was directly based upon the correlation between the work activities she complained of and the dystonia he repeatedly observed. Secondly, although the fact of his high position in the field would not in itself necessarily provide a sound reason for preferring his evidence over that of other experts, the fact that he was an acknowledged expert in movement disorders[15] and leader of the movement disorders service at the Royal Melbourne Hospital was contextually relevant to the credibility of an opinion he expressly based upon his clinical experience. Thirdly, his evidence was supported by Professor Cook and both Dr Evans and Professor Cook explained their opinions orally and maintained their opinions despite the matters put to them in cross-examination. Next, Dr Evans's evidence was in turn supported by Mr Hjorth by reference to his clinical experience. The opinion of Dr Evans cannot be regarded as idiosyncratic or fanciful.

57 It follows that I do not accept the appellants' primary submission that her Honour failed to address the logic of the appellants' expert opinions and provide a sensible basis for her decision. In my view, she gave entirely logical reasons for preferring the opinions which she did and that preference was properly dispositive of the issues before her. It was not for her to purport to form her own neurological opinion but rather to justify the preference of the expert opinions which she accepted.

58 It is next submitted that her Honour's finding did not directly address the question of whether, and if so to what degree, the plaintiff's injury was constituted by an aggravation. Injury is defined by s 5 of the Act as follows:

injury means any physical or mental injury and, without limiting the generality of that definition, includes -

(a) industrial deafness;

(b) a disease contracted by a worker in the course of the worker's employment (whether at, or away from, the place of employment);

(c) a recurrence, aggravation, acceleration, exacerbation or deterioration of any pre-existing injury or disease; ... .

59 An injury constituted by an aggravation of a pre-existing injury will not be a serious injury unless it itself is serious. In the present case there was in my view some looseness in the differentiation of the concepts of a 'contributing factor' and 'aggravating factor' in the medical evidence. Thus the sense in which Dr Evans spoke of an ongoing aggravation was not aggravation of a pre-existing condition. It may also be noted that whilst it is true Professor White was initially of the view that there was likely to be an underlying tendency to the development of dystonia that had been aggravated by the nature of the plaintiff's work, this evidence also did not raise the aggravation issue now postulated by the appellants. What it contemplated was that the pre-existing condition was no more than a tendency. Moreover both the ultimate opinion of Professor White and the opinion of Professor Helme was that there was no probable connection between the plaintiff's work and her condition. In turn it was not put to the plaintiff's experts that any work related aggravation was not serious. What was put was that the condition was idiopathic. In final submissions to the trial judge counsel for the appellants put the case this way.

... our thesis is that the plaintiff has developed the dystonia of unknown etiology and that following the normal pattern it has not got better, and in those circumstances there is no question in relation to degree of aggravation. It cannot on a review of the evidence stand. This is not an aggravation case, it is a causation case of the initial condition.

60 Once the trial judge accepted that the plaintiff's condition was caused by her work it was open to her Honour to respond to the manner in which the parties put their cases by simply finding that the plaintiff's work was a cause of that injury.

Professor Helme and the weight of the evidence

2. The primary judge -

(a) failed to have regard to the evidence of Professor Helme or to the fact that Professor Helme's evidence was not challenged by cross examination;

(b) erred at [46] of the reasons in placing less weight on the evidence of Dr David Freilich, Dr Michael Poon and Dr Clayton Thomas because their evidence was not tested in court; and

(c) erred at [45] of the reasons in placing greater weight on the evidence of Dr Andrew Evans, Professor Mark Cook and Associate Professor Owen White because their evidence was tested in court.

1. In consequence of the errors in [2] above, the primary judge's weighing of the evidence was distorted.

63 I do not accept that her Honour failed to have regard to Professor Helme's evidence. She summarised it accurately and referred to it in her final analysis. As was stated in Woolworths Ltd v Warfe:[16]

The adequacy of the reasons must depend upon the issues, and nature of the proceeding, in any individual case. In an appropriate case, reasons can be adequate by a combination of what is expressly stated and the inferences that necessarily arise from what is expressly stated. Thus, as Neave JA and Beach AJA stated in Murray Goulburn Coop Co Ltd v Filliponi:

In some cases, the path of reasoning which led to the ultimate conclusion is necessarily implicit in a sufficiently detailed recitation of the relevant material upon the decision was based.

64 Furthermore, her Honour was correct to observe that Professor Helme's evidence was essentially consistent with that of Professor White. Like Professor White, Professor Helme's opinions were critically dependent upon his reading of the medical literature. In his report of 6 February 2012 he said of cervical dystonia:

Dr Hjorth and I agree that the cause of cervical dystonia is often unclear, that it is unknown or idiopathic. It can occur as part of a generalised neurologic disorder and rarely from medications. That it can occur as a result of a demonstrable injury or infection in the upper cervical spine is also found in the medical literature ...

What is less clear is whether it can occur as a result of adopting a fixed or stressful neck posture as part of the work environment. There is, to my knowledge, no credible literature on this point ... Nevertheless, other focal dystonias have been recognised to be strongly related to prolonged stressful posture and repetitive motor performance such as may be seen, for example, in the hands and fingers of professional violin and piano players.

It has therefore been speculated that this mechanism may also apply to cervical dystonias. I cannot discount the possibility, but consider it most unlikely given the lack of evidence in the medical literature. As the condition occurs mostly in mid life, a temporal association between the onset of the condition and work can easily be made (eg Dr Hjorth's clinical experience at the Royal Melbourne Hospital) but whether this is causal remains unproven.

65 This passage was read to her Honour in final address by counsel for the appellants and it was this central argument of Professor Helme's that the appellants relied on. After reading the above passage from Professor Helme's report in final address counsel for the appellants said:

Our point is Your Honour, how can it be that the majority of these cases come before the specialists without any history of repetitive movement? When I say these cases I mean cervical dystonia, and they come to them in adulthood, the majority come to them once it develops in adulthood without a history of repetitive movement et cetera. Then how is it that you then jump and say, 'Well, oh, she's working in the laundry, it's work-related', when the majority come saying, 'I've got this and it can't be put down to any reason' as acknowledged by the authors of the reports themselves.

66 Ultimately her Honour was confronted with two camps of thought: that which discounted the plaintiff's case because of the absence of support in the medical literature for a proven causal link of the type postulated, and that which did not. In turn her Honour adequately explained why she preferred the opinion of Dr Evans based on clinical experience.

67 Lastly, insofar as Professor Helme expressed opinions about work activities shown to him on DVDs, it appears some of that material was not supplied to the other witnesses.[17] Moreover and in any event, Dr Evans's opinions were not simply based upon the DVD material but upon the plaintiff's direct description of her work during the course of her treatment which (consistently with her affidavit evidence) indicated a more rapid and stressful repetitive series of movements than those shown on the DVDs. It was not in my opinion necessary for her Honour to say more about the DVD evidence given the manner in which the parties joined issue before her.[18]

68 It is next asserted that her Honour erred in failing to acknowledge that Professor Helme's evidence was not challenged in cross-examination. In the course of final submissions, counsel for the appellants said:

We adopt Professor Robert Helme's view, unchallenged. Now we make no criticism of our friends and we don't take any point about any issues about doctors being unchallenged.

69 It is not surprising that no criticism was made because both parties relied in part upon reports which were not the subject of cross-examination. There is nothing in this point.

70 It is further said that her Honour erred in placing more weight upon the evidence of the witnesses who gave evidence orally before her than upon those who did not. It should be noted that oral evidence was called from witnesses on both sides of the debate and that each of these witnesses (including Professor White) amplified their evidence in chief before cross-examination. It was open to the appellants to call further oral evidence whether or not the witnesses were required by the respondent for cross-examination. In turn it was open to her Honour to give greater weight to the opinions amplified and defended in oral evidence before her. Having read the transcript it is hardly surprising that she did so.

71 In the event, the principal competing views were explained in oral evidence called by both parties. Her Honour's decision was not principally determined by the distinction between oral and written evidence. In referring to the fact that Dr Evans and Professor Cook gave oral evidence in final reasoning, her Honour did no more than identify a circumstance supporting her acceptance of their opinions. There was no error in this.

73 I have had the advantage of reading in draft the reasons of Osborn JA. I agree with his Honour that the appeal should be dismissed for the reasons he gives, and would add a few observations of my own.

74 The appellant conceded before the trial judge that the respondent had suffered a serious injury, being cervical dystonia. The matter at issue was whether the respondent's employment was a cause of her condition.

75 The appellant contends that the medical evidence fell into two camps. Both groups agreed that it was possible that the respondent's employment was a cause of her condition. Both groups agreed that it was possible that the respondent's employment was not a cause of her condition.

76 Dr Evans (and those that agreed with his views) said that on balance it was probable that the respondent's employment was a cause of her condition. Professor Helme (and those that agreed with his views) expressed the opinion that it was unlikely that the respondent's employment was a cause of her condition.

77 Each of the opposing camps gave considered reasons for their views. In substance, Dr Evans placed emphasis on the clinical observations that he had made in the course of his practice. Professor Helme and those that agreed with his view placed emphasis on the medical literature and the fact that - according to their research - there was only one reported case (outside of musicians) where physical activities were identified as the cause of cervical dystonia.

78 The learned trial judge carefully set out the reasoning and views of all the experts. Her Honour held that she was persuaded by the evidence of Dr Evans that, on the balance of probabilities, the respondent's employment was a cause of her injury.

79 The appellant contends that the learned trial judge did not properly disclose her reasoning in being persuaded by the evidence of Dr Evans (and those that agreed with his opinion). The appellant submits that, despite the fact that Professor Helme's evidence was central to the appellant's case, it was not evaluated at all. The appellant says that if it is implicit in her Honour's ultimate finding that Professor Helme's evidence was rejected, then the reasons do not explain why this evidence was rejected.

80 The appellant submits that the learned trial judge was bound to explain why Professor Helme's evidence was rejected. In support of that proposition the appellant refers to and relies on the decision of Nettle JA in Hunter v Transport Accident Commission,[19] where his Honour said:

When a judge decides an application under s 93(4)(d) of the Act the judge is under a duty to provide reasons for his or her decision. Furthermore, while the extent of the reasons will depend upon the circumstances of the case, the reasons should deal with the substantial points which have been raised; include findings on material questions of fact; refer to the evidence or other material upon which those finding are based; and provide an intelligible explanation of the process of reasoning that has led the judge from the evidence to the findings and from the findings to the ultimate conclusion. It should also be understood that the requirement to refer to the evidence is not limited to the evidence that has been accepted and acted upon_. If a party has relied on evidence or material which the judge has rejected, the judge should refer to that evidence or material and, in giving reasons which deal with the substantial points that have been raised, explain why that evidence or material has been rejected._ There may be exceptions. But, ordinarily, where a judge rejects or excludes from consideration evidence or other material which is relevant and cogent, it is simply not possible to give fair and sensible reasons for the decision without adverting to and assigning reasons for the rejection or exclusion of that material. Similarly, while it is not incumbent upon the judge to deal with every argument and issue that might arise in the course of a case, where an argument is substantial or an issue is significant, it is necessary to refer to and assign reasons for the rejection of the argument or the resolution of the issue. Above all the judge should bear steadily in mind that reasons are not intelligible if they leave the reader to wonder which of a number of possible routes has been taken to the conclusion expressed. Failure to expose the path of reasoning is an error of law.[20]

81 Expert witnesses who give opinion evidence must also disclose the path of reasoning that has led them to the opinion they express. In Makita (Australia) Pty Ltd v Sprowles,[21] Heydon JA held that it was the primary duty of an expert giving evidence to furnish the trier of fact with criteria enabling evaluation of the validity of the expert's conclusion. His Honour spoke of the need for the intellectual basis of the opinion to be fully explained to the trier of fact,[22] and the need to explain 'the essential integers underlying' the expert's opinion.[23]

82 There is authority on the duty of a judge to give reasons for preferring one expert's opinion over another. In Clutha Ltd v Risby,[24] the New South Wales Court of Appeal considered an appeal by an employer in a worker's compensation claim where the appellant claimed that the trial judge had not given adequate reasons for his conclusion in favour of the worker. The trial judge had been faced with two conflicting medical opinions as to whether there was a causal relationship between the respondent's work and his rare form of cancer. The trial judge accurately summarised the conflicting opinions and said - without explanation - that on the balance of probabilities he was satisfied that applicant had discharged his onus.

83 Justice of Appeal Clarke (with whom Cole JA and Hunter AJA agreed) held that where there were diametrically opposed views given by two eminent specialists, the trial judge was bound to explain why it was that he preferred the views of one. His Honour held that an elaborate explanation was not necessary. It was necessary, however, for the trial judge to explain the factors which led him to accept the worker's case.

84 In Flannery v Halifax Agencies Ltd (trading as Colleys Professional Services),[25] the English Court of Appeal considered an appeal on the grounds that the trial judge had not given adequate reasons why he preferred the reasoning of one expert over another. In that case, engineering experts had been called on the issue of whether a flat, which had been valued by the defendant, was or was not subject to structural movement at the time of valuation. Lord Justice of Appeal Henry, who delivered the decision of the Court,[26] held that where the dispute involves something in the nature of an intellectual exchange, with reasons and analysis advanced on either side, the judge must enter into the issues canvassed before him and explain why he prefers one case over the other.[27] His Honour said that this was particularly so where there is disputed expert evidence.

85 In English v Emery Reimbold & Strick Ltd; DJ & C Withers (Farms) Ltd v Ambic Equipment Ltd; Verrechia (trading as Freightmaster Commercials) v Commissioner of Police for the Metropolis,[28] the English Court of Appeal (Lord Phillips MR, Latham and Arden LJJ) dealt with a series of cases where appeals had been made on the grounds that the trial judge had failed to give adequate reasons. Lord Phillips delivered the judgment of the Court, to which all members had contributed. In dealing with competing experts, Lord Phillips referred to the judgment of Henry LJ in Flannery,[29] where his Honour quoted from Bingham LJ in Eckersley v Binnie (in which Bingham LJ said that 'a coherent reasoned opinion expressed by a suitably qualified expert should be the subject of a coherent reasoned rebuttal'.)[30] Lord Phillips said:

This does not mean that the judgment should contain a passage which suggests that the Judge has applied the same, or even a superior, degree of expertise to that displayed by the witness. He should simply provide an explanation as to why he has accepted the evidence of one expert and rejected that of another. It may be that the evidence of one or the other accorded more satisfactorily with facts found by the Judge. It may be that the explanation of one was more inherently credible than that of the other. It may simply be that one was better qualified, or manifestly more objective, than the other. Whatever the explanation may be, it should be apparent from the judgment.[31]

86 In relation to a direct conflict between expert evidence, Lord Phillips MR said:

It is legitimate, where there is a direct conflict of expert evidence, for the Judge to prefer the evidence of one expert to the other simply on the ground that he was better qualified to give it, or was a more authoritative witness, if the Judge is unable to identify any more substantial reason for choosing between them. This should not often be the case. If this is the basis for the Judge's conclusion, he should make it plain.[32]

87 In Drake v Thos. Agnew & Sons Ltd,[33] Buckley J, sitting in the Queen's Bench Division, held that a relevant matter in deciding between competing expert opinion is the acknowledged expertise and experience of an expert. In Drake, the Court was called on to decide whether or not a portrait, James Stuart, 4th Duke of Lennox and 1st Duke of Richmond, was an autograph work of the Old Master artist Sir Anthony van Dyck (as opposed to a studio copy). Two experts disagreed; Sir Oliver Millar said that it was not an autograph work by van Dyck, whilst Mr Julian Agnew said that it was.[34]

88 Justice Buckley said that a judge was not bound by expert opinion. His Honour said that:

A judge may presume to find that an expert's final opinion is based on illogical or even irrational reasoning and reject it. But a judge should not himself assume an expertise he does not possess. Thus here, if the question had turned on analysis of historical data or inferences to be drawn from surviving documents, I would have been entitled, with such assistance from the experts as I had received, to have drawn my own conclusions; but it does not. It turns on 'eye'. However I may regard my own taste or appreciation of things artistic, I must not presume to have an expert's 'eye' for a van Dyck.[35]

89 After considering the experts' evidence in detail, Buckley J accepted the evidence of Sir Oliver, as his 'experience, knowledge and general expertise concerning van Dyck's English Period are unrivalled', even though his Honour 'was impressed by Mr Agnew's expertise and obvious love of his subject' and made no criticism of Mr Agnew's evidence.[36] His Honour was at pains to point out that his preference for Sir Oliver's evidence was 'significantly influenced by the acknowledged greater expertise that Sir Oliver possesses in relation to these works', and that his decision was 'a legal one based upon the evidence and the circumstances of the experts', rather than being based on any connoisseurship his Honour may have acquired in the course of the exhaustive evidence given (ie the judge did not attempt to substitute his own expertise).[37]

90 In the present case, the learned trial judge was not called on to decide that any of the factors relied on by the various experts were factually incorrect. For example, her Honour was not asked to find that Dr Evans did not observe what he said he had observed in clinical situations. Her Honour was not called on to find that the literature relied on by Professor Helme should be rejected or accepted.

91 Accordingly, her Honour was not called on to reject an opinion on the basis that it was founded on false factual assumptions. Rather, her Honour was faced with opposing opinions based on different criteria, where those criteria had not been challenged. As the authorities discussed above indicate, when faced with expert opinion, it was not her Honour's function to substitute her Honour's opinion for that of the experts.

92 The learned trial judge acknowledged that the difference between the opinions was slight. Her Honour spelled out the factors that led her to favour one expert view over another. Her Honour placed weight on the evidence of medical witnesses whose opinion was tested in Court. That is a relevant factor that her Honour was entitled to take into account.[38] Her Honour said that she was persuaded by the evidence of Dr Evans. Her Honour relied on the fact that Dr Evans had treated the plaintiff in excess of four years, he was an acknowledged expert in movement disorders, and led the Movement Disorders Service at the Royal Melbourne Hospital. Theses were all relevant factors for her Honour to take into account.

93 Her Honour said that Dr Evan's evidence was supported by Professor Cook, and that both witnesses gave evidence in Court. Her Honour took into account that their evidence was supported by Mr Hjorth, a consultant neurologist. Her Honour acknowledged that Dr Freilich, Dr Poon and Dr Thomas did not accept work was a cause of the injury. Her Honour placed less weight on their evidence because it was not tested in Court and gave further explanations for not accepting their opinions.

94 In my opinion, the matters her Honour relies on were all matters properly taken into account, and exposed her Honour's path of reasoning in being persuaded by Dr Evan's opinion over that of Associate Professor White's opinion (which was consistent with the opinion of Professor Helme).

95 When faced with competing opinions which are both supported by sound reasoning, in my opinion, the Court's function is to decide the issue at hand and that may require the Court to accept one opinion over the other. In doing so, the Court would not normally substitute its opinion on a medical diagnosis of a patient for that of the experts and give scientific medical reasons for doing so. As discussed above, the trial judge's persuasion to prefer one opinion over another may well be based on factors such as that the expert's opinion was tested under cross-examination, or that the opinion was given by a person eminent in his or her field, or that the opinion was supported by clinical observations. Not all disputes between experts can be dealt with by rejecting one of the competing opinions because it displayed faulty reasoning or was based on a false assumption. Such was the case, in the matter before her Honour.

96 For these and the reasons given by Osborn JA, I agree that the trial judge gave adequate reasons for finding that she was persuaded by Dr Evan's evidence (and those that supported his view) as against Professor Helme's evidence (and those that supported his view) that, on the balance of probabilities, the plaintiff's employment was a cause of her condition.

[1] Section 134AB(2) provides:

A worker may recover damages in respect of an injury arising out of, or in the course of, or due to the nature of, employment if the injury is a serious injury and arose on or after 20 October 1999.

[2] Zlatevska v Consolidated Cleaning Services Pty Ltd [2006] VSCA 141, [8].

[3] Mircevic v Alsco Pty Ltd & Anor [2012] VCC 1603 ('Reasons'), [7]-[8].

[12] Mobilio v Balliotis [1998] 3 VR 833.

[13] Accident Compensation Act 1985 s 390.

[14] Hunter v Transport Accident Commission [2005] VSCA 1; Franklin v Ubaldi Foods Pty Ltd [2005] VSCA 317.

[15] Professor White agreed in cross-examination that Dr Evans was 'highly regarded in his field'.

[16] [2013] VSCA 22l, [131] (citations omitted).

[17] Reasons [38]: 'I was informed that no one else has seen the [last] DVD referred to by Professor Helme.'

[18] Sun Alliance Insurance Ltd v Massoud [1989] VicRp 2; [1989] VR 8 . See also Woolworths Ltd v Warfe [2013] VSCA 22, [83] where Kaye AJA (with whom Tate and Whelan JJA agreed) said : 'The question, as to the sufficiency of the trial judge's findings, is not determined solely from the text of the reasons for judgment. A judge's reasons, particularly on a serious injury application, must be considered in light of the issues which were agitated at the trial'.

[19] [2005] VSCA 1.

[20] Ibid [21] (citations omitted) (my emphasis).

[21] [2001] NSWCA 305; (2001) 52 NSWLR 705.

[24] [1996] NSWCA 106 (see also Soulemezis v Dudley (Holdings) Pty Ltd (1987) 10 NSWLR 247, which is cited with approval therein).

[25] [1999] EWCA Civ 811; [2000] 1 WLR 377 ('Flannery').

[27] Flannery 382; approved and relied on in Moylan v The Nutrasweet Company [2000] NSWCA 337, [63]-[66] ( Sheller JA, with whom Beazley and Giles JJA agreed).

[28] [2002] EWCA Civ 65 (English v Emery Reimbold) (cited in Evan Bell, 'Judicial Assessment of Expert Evidence' (2010) 10(2) Judicial Studies Institute Journal 55, 75 (FN92)).

[30] Eckersley v Binney (1998) 18 Con LR 1, 77-78.

[31] English v Emery Reimbold [20].

[32] English v Emery Reimbold [73].

[33] [2002] EWHC 294 (Drake).

[34] As Buckley J noted (in [41]-[42]), each expert was suitably qualified and - although both were 'involved in the affair and thus gave factual as well as expert evidence' and 'obvious points as to weight and objectivity were politely canvassed' - his Honour 'found no reason to doubt the integrity of either witness.'

[38] See discussion in Flannery, 380; and Evan Bell, 'Judicial Assessment of Expert Evidence' (2010) 10(2) Judicial Studies Institute Journal 55, 87-88 (and cases cited therein).