De La Rosa v Dominion Global Pty Ltd

CERTIFICATE OF DETERMINATION OF MEMBER
CITATION:	De La Rosa v Dominion Global Pty Ltd [2023] NSWPIC 474
APPLICANT:	Jefferson de la Rosa
RESPONDENT:	Dominion Global Pty Limited
MEMBER:	Paul Sweeney
DATE OF DECISION:	14 September 2023
CATCHWORDS:	WORKERS COMPENSATION - Claim for permanent impairment compensation; worker contracts malaria in the course of his employment in a Papua New Guinea; he alleges that the condition of trigeminal neuralgia results from injury; employer denies liability arguing that was no adequate evidence in the scientific literature to establish a causal nexus and there were alternative causes of trigeminal neuralgia; Seltsam Pty Limited v McGuiness considered; worker’s medical evidence posited possible mechanisms for a connection between injury and trigeminal neuralgia; worker’s medical case preferred; Held – finding that trigeminal neuralgia resulted from malaria; medical dispute remitted for assessment.
DETERMINATIONS MADE:	The Commission determines: 1. On or about 18 August 2020, the applicant contracted malaria arising out of and in the course of his employment with the respondent at Lihir Island in Papua New Guinea. 2. As a result of that injury the applicant developed the condition of trigeminal neuralgia. 3. Remit the matter to the President for referral to a Medical Assessor to certify the degree, if any, of whole person impairment as a result of the condition of trigeminal neuralgia. 4. Medical Assessor to have access to the Application, the Reply, the Application to Admit Late Documents and the documents attached to each together with a copy of these reasons.

STATEMENT OF REASONS

BACKGROUND

Jefferson de la Rosa (the applicant) was employed by Dominion Global Pty Limited (the respondent) as a trades assistant. In August 2020, he was required to perform maintenance work at a gold mine on Lihir Island in Papua New Guinea. On 19 August 2020, he developed a fever and headaches which was subsequently diagnosed as malaria.
When the applicant’s headaches and facial pain continued he was transferred to Pacific International Hospital in Port Moresby. On 28 August 2020, he returned to Australia and was treated at the Emergency Department of the Royal Brisbane and Women’s Hospital. While he was undertaking quarantine in Brisbane he developed increasing headaches and facial pain.
On 11 September 2020, the applicant left Brisbane and returned to Newcastle, New South Wales. While there was some amelioration of his symptomatology, the applicant had acute episodes of facial pain in October and November 2020. He was treated at Blacktown Hospital and at Ryde Hospital. He came under the care of Drs Dexter and Smail, both of whom are neurologists, and Dr Newcombe, a specialist in infectious diseases and microbiology.
It is common ground that the applicant suffered plasmodium vivax malaria arising out of and in the course of his employment with the respondent on Lihir Island. It is also accepted by the respondent’s qualified specialist that the applicant suffers from trigeminal neuralgia.
The applicant maintains that the trigeminal neuralgia results from the malaria. The respondent, however, denies that trigeminal neuralgia results from injury.

PROCEDURE BEFORE THE PERSONAL INJURY COMMISSION

By these proceedings, the applicant claims permanent impairment compensation pursuant to s 66 of the Workers Compensation Act 1987 (the 1987 Act) for an impairment resulting from trigeminal neuralgia. The respondent disputes that it is liable to pay compensation as it has not been established that there is a causal nexus between the malaria and trigeminal neuralgia.
When the matter came on for conciliation and arbitration on 4 September 2023, Mr Barter, of counsel, appeared for the applicant and Mr Hunt, of counsel, appeared for the respondent.
I was informed by counsel that the parties were unable to reach an agreement to resolve the issue in dispute. I am satisfied that the parties have had ample opportunity to consider settlement during the lengthy history of the matter but were unable to formulate a mutually acceptable resolution.

EVIDENCE

The documents before the Personal Injury Commission (Commission) are as follows:
(a)    Application to Resolve a Dispute and the documents attached;
(b)    Reply and the documents attached, and
(c)    Application to Admit Late Documents dated 24 August 2023 and the documents attached.
There was no objection to the material referred to above and neither party sought to adduce further written or oral evidence.

SUBMISSIONS

The submissions of the parties are recorded and I do not propose to reiterate each of those submissions in these short reasons.
Mr Hunt submitted that the opinion of Dr Granot, the respondent’s qualified neurologist, on the issue of causal nexus should be preferred to the opinions in the applicant’s case. He primarily relied on the failure of the medical practitioners, who expressed the opinion that there was a causal nexus between the applicant’s malaria and his left trigeminal neuralgia, to address an MRI scan of the brain and skull dated 25 March 2021. Relevantly, this was reported by the radiologist as follows:
“The left superior cerebellar artery is seen coursing just superior to the cisternal portion of the left trigeminal nerve with apparent contact which may give rise to irritation.”
On reviewing the films, Dr Granot expressed the opinion that the proximity of the cerebellar artery to the trigeminal nerve was congenital and constituted a physical abnormality which could explain the applicant’s facial symptoms. That opinion was not contradicted by the applicant’s medical case.
Mr Hunt also submitted that dental treatment undertaken by the applicant on
17 September 2020 was a more plausible cause of trigeminal neuralgia than malaria. Further, the epidemiological research only suggested a tenuous link, if any, between plasmodium vivax malaria and the onset of trigeminal neuralgia.
Mr Barter submitted that the applicant’s treating neurologists and infectious disease specialists and his qualified neurologist Dr Teychenné had each concluded that there was a probable link between malaria and the onset of trigeminal neuralgia. Mr Barter emphasised that Dr Newcombe, the only infectious diseases expert retained in the case, had expressed the clear opinion that there was a “circumstantial” link between malaria and the applicant’s current symptoms. He submitted that while a temporal connection was insufficient to establish causation, it was one of the links in the chain that the Commission could consider in reaching its conclusion as to the presence or absence of causal nexus.
Before attempting to resolve the issues in dispute, it is necessary to compendiously set out the evidence of the applicant and that of the two neurologists, Dr Teychenné in the applicant’s case and Dr Granot in the respondent’s case. What follows is not intended to be a comprehensive survey of this evidence. Rather, I set out the salient points so that the parties may understand the way in which the Commission has resolved their dispute.

The applicant

By his written statement the applicant says that prior to commencing employment with the respondent in 2019, he had not experienced pain in his face. He says that while working at Lihir Island on 18 August 2020 he was bitten by a mosquito and developed fevers, vomiting and stomach pains.
The applicant was seen by a doctor on 22 August 2020 who diagnosed plasmodium vivax malaria and prescribed medication. He was transferred to the Pacific International Hospital in Port Moresby where he was treated in the emergency room. On 28 August 2020, he returned to Brisbane and admitted to the Royal Brisbane and Women’s Hospital where he reported experiencing “headaches and forehead pain” since he contracted malaria.
While in quarantine in Brisbane, he returned to the emergency department at the hospital on 7 September 2020 complaining of:
“worsening headache as well as left jaw pain, cheek pain, temporal pain and ear pain since being diagnosed with malaria.”
The applicant recounts that he was diagnosed with “likely trigeminal neuralgia” and prescribed Carvamazepine.
The applicant continued to take Carvamazepine after he completed quarantine and travelled from Brisbane to Newcastle on 11 September 2020. He sought medical treatment from
Dr Yin Lin of the Appletree Medical Practice. He returned to work on 20 October 2020.
On 15 November 2020, the applicant states that he experienced “an extreme episode of neurological pain in the right side of my face” whilst working in Bathurst. He attended the Bathurst Hospital.
On 16 December 2020, the applicant consulted with Dr Lin as he was still experiencing severe pain in his face. Dr Lin referred the applicant to Dr Mark Dexter, a neurologist, at Westmead Private Hospital for review. Dr Dexter prescribed amitriptyline and Valium.
On 14 January 2021, the applicant consulted Dr Smail at Sydney North Neurology who advised him to continue to take Carvamazepine, amitriptyline and Endep in an attempt to lessen his facial pain.
On 25 January 2021, the applicant attended Ryde Hospital following the onset of severe facial pain.
The applicant says that he is currently trialling “new medications” prescribed by Dr Smail to ascertain which may provide optimal pain relief. Dr Dexter has apparently advised the applicant that his condition is not likely to be completely cured but there are surgical procedures which may help.

Dr Teychenné

Dr Teychenné saw the applicant at the request of his solicitor on 12 May 2021 and provided a report of 10 June 2021. Dr Teychenné reviewed the applicant’s clinical history which is largely consistent with the applicant’s statement evidence. The applicant was diagnosed with plasmodium vivax malaria while in New Guinea. He was diagnosed with possible trigeminal neuralgia at the Royal Brisbane and Women’s Hospital on 28 August 2020 upon his return to Australia.
In reviewing the literature, Dr Teychenné referred to an article by Garg et al, Neurology India, Vol 47, issue 2, pp 85-97, 1999 entitled Neurological Manifestations of Malaria. He states that the authors:
“indicate that there are post-malaria neurological syndromes and indicate that cerebellar involvement is the most consistent neurological manifestation of complicated as well as uncomplicated malaria. They mention neurologic complications of both complicated and uncomplicated malaria may be Guillain-Barre Syndrome-like presentation, mononeuritic syndrome such as facial palsy, retrobulbar optic neuritis, and involvement of ulnar, circumflex, and lateral popliteal nerves as well as trigeminal neuralgia. Neurological manifestations may also be due to anti-malarial drugs.”
After referring to an article by Saggu et al in the American Journal of Pathology, the doctor continued:
“Based on these reports of clinical assessment and experimental assessment, it is apparent that both complicated malaria (cerebral malaria), and uncomplicated malaria may result in trigeminal neuralgia and it is probable based on the confluence of symptoms that Mr de la Rosa did have an episode of cerebral malaria which may occur with plasmodium vivax malaria.”
Dr Teychenné also examined the applicant. He considered that he suffered from trigeminal neuralgia. On causation, he expressed the following opinion:
“I did consider there was a temporal relationship to the onset of headaches with the onset of plasmodium vivax malaria.”
He continues:
“On this basis I would have to consider that his employment was the main contributing factor to his subject injury and/or condition, subsequent incapacity and need for treatment.”
He concluded that there was enough “published data” to make a connection between malaria and trigeminal neuralgia.
Relevantly, Dr Teychenné provided a supplementary report dated 9 April 2023.
Dr Teychenné reviewed the more recent medical evidence in the case including the opinions of Dr Smail and Dr Peck. He expressed the opinion that a symptom-free period from mid-October to November 2020 “would not be unusual in trigeminal neuralgia”. He also reviewed the reports of Dr Granot, although his response to Dr Granot’s report is at a highly theoretical level.
Dr Teychenné also considered the opinion of Dr Peck that the applicant suffered post-malarial neurological syndrome or central sensitisation. However, he considered that the most likely diagnosis was malarial encephalopathy which localised into trigeminal neuralgia. He concluded by stating:
“While Mr de la Rosa’s persisting symptoms could result from nervous system sensitisation triggered by or otherwise compromised by exposure to or recovery from plasmodium vivax malaria I considered that Mr de la Rosa had symptoms of Trigeminal Neuralgia developing as part of the Plasmodium Vivax infection in August 2020.”

Dr Granot

Dr Granot consulted with the applicant by tele-health on 13 August 2021 and provided a report to the respondent’s solicitor on 16 August 2021. After reviewing the extensive clinical record and taking a history from the applicant, he concluded that the applicant’s symptoms:
“are currently consistent with trigeminal neuralgia, including transient neuropathic shooting paroxysms of pain, with typical triggering by local contact both over the cheek and upon eating or chewing. I do not believe that this is consistent with atypical facial pain.”
However, Dr Granot doubted that this condition was caused by the applicant’s employment. First, he questioned whether the applicant developed malaria while working on Lihir Island. He stated:
“There is no evidence provided to confirm the diagnosis of malaria. He did not take anti-malarial prophylaxis which is surprising but claims this is on the basis of advice provided him by a company employee. There is no evidence that he took separate medical advice from any other practitioner specialising in travel medicine.”
Assuming that the applicant did contract vivax malaria on Lihir Island, he also doubted the connection between malaria and trigeminal neuralgia. He said this:
“The literature review in particular references those articles that all other examiners have relied upon. The issues in this case are lack of evidence that vivax malaria is linked to neurological complications, that such neurological complications if linked transient [sic] and that the overall rate of correlation between malaria as a cause for trigeminal neuralgia is very small and therefore of uncertain strength to define it as a definite aetiology. Finally, there is the difficulty of defining an etiological agent simply upon timing which is the post hoc ergo propter hoc logical fallacy. Alternatively, there is evidence of trigeminal compression by the superior cerebellar artery, which would be a much more common and accepted etiological agent.”
The doctor’s reference to compression of the trigeminal nerve by the left cerebellar artery picks up the comment of Dr Tse in the MRI brain and skull based scan of 25 March 2021, which I have set out above.
By a supplementary report of 7 December 2021, Dr Granot considered whether a tooth extraction on 17 September 2020 was relevant to the onset of trigeminal symptomatology. After noting that the applicant did have a wisdom tooth extracted prior to the recurrence of his trigeminal symptomatology, the doctor addressed the question of causation. He said this:
“This remains vexed. According to the understood medical literature, the vascular contact of the trigeminal nerve remains the most likely cause of his trigeminal neuralgia. A reasonable alternative hypothesis is the complication of a dental extraction, which has been reported to be associated with both continuous and intermittent (neuralgia) type pain, as is documented above.”
The doctor noted that the opinion expressed in his previous report was “supported by the recent report of Dr Mark Douglas”. There were more likely and common causes of trigeminal neuralgia in this case:
“namely the vascular contact and now possibly the dental extraction, than the much less likely/established possibility of malaria.”
Dr Granot provided a further report dated 26 June 2023 in which he reviewed the opinion of Dr Teychenné dated 9 April 2023, the imaging from the MRI dated 25 March 2021, and the records from Belle Dental and Hills Endodontics relating to the extraction of the applicant’s left wisdom tooth. Dr Granot responded to Dr Teychenné’s recent opinion thus:
“I shall return once again to my discussion of causation from my original IME, which discussed the details of the Garg paper that Dr Teychenné relies once again upon to make his connection between the malaria and the Trigeminal neuralgia. I quoted extensively from the paper to demonstrate that the syndrome is described as transient, that vivax malaria was not associated with such a syndrome either, despite speculation that it may be. Further, the Trivedi paper referred to only mentions trigeminal neuralgia in general form, not addressing any question about vivax or falciparum.”
Dr Granot also doubted whether the fact that the applicant had previously experienced symptom-free periods was consistent with an idiopathic trigeminal neuralgia based upon an irritative lesion on the trigeminal nerve by a nearby blood vessel. If the neuralgia was triggered by the malaria “the mechanism is vascular and hence ischemic, not irritative”. In those circumstances, a patient would not experience remission of symptoms.
Dr Granot also expressed the opinion that if the applicant had an auto-immune encephalitis as Dr Teychenné as a possible alternative cause of the neuralgia, changes of encephalitis would be expected to be demonstrated on imaging “which has not been the case at any point”.
Dr Granot concluded by stating:
“As noted in my original report, the recent MRI does show direct vascular contact (demonstrated below) on the left side only of the superior cerebellar artery coursing through the trigeminal nerve. This is clearly developmental, not acquired, and is clearly the most likely cause of trigeminal neuralgia in general and in this particular case.”
Dr Granot, once again, opined that the other alternative cause of the trigeminal neuralgia related to the dental surgery on 17 September 2021 as discussed in his earlier report.

DISCUSSION AND FINDINGS

As the claim before the Commission is solely for permanent impairment compensation,
[1] [2014] NS WCCPD 79 (10 March 2015).
I have approached it on the basis that the function of the Commission is to determine liability issues. In this case, that involves a determination of whether trigeminal neuralgia is an injury or a consequential medical condition. Whether the injury/condition is permanent or transient and whether a deduction should be made for pre-existing or supervening causes are matters solely within the prerogative of a Medical Assessor: see Jaffarie v Quality Castings Pty Ltd.[1]
Mr Hunt commenced his submissions by arguing that the hypothesis that the applicant’s trigeminal neuralgia was caused by a bout of malaria was largely based on the close temporal relationship between the two conditions. Consonant with the argument propounded by Dr Granot, he submitted that causation was not established merely because one event followed the other. Dr Granot referred to the maxim “post hoc ergo propter hoc” which frequently appears in the case law dealing with causation.
I accept that it is erroneous to reach a conclusion as to causal nexus’s solely on the basis of temporal relationship. If the gist of the medical evidence in a case is that there is no possible connection between an incident and a condition, that is the end of the matter. However, if a causal connection is possible a court is entitled to evaluate all of the evidence in determining whether causal nexus has been established on the balance of probabilities.
In performing that task, there can be no doubt that contemporaneity is often an important factor in identifying cause. Whether a worker suffers an injury as a result of a particular incident may often depend on whether there is a complaint of pain at the site of the injury within a short time of the incident. There are many other examples. In Seltsam Pty Limitedv McGuiness; James Hardie & Coy Pty Limited v McGuiness,[2] Spigelman CJ addressed the approach of the common law to proof of causation. While the immediate concern of the Court was the use of epidemiological evidence to establish the legal cause of an injury, the reasoning is of more general importance. At [83] to [98], his Honour said this:
[2] [2000] NSWCA 29 (7 March 2020) (Seltsam).
“83 The law in Australia is, in my opinion, as stated by Glass JA in this Court in Fernandez v Tubemakers of Australia Ltd (1975) 2 NSWLR 190 at 197:
‘The issue of causation involves a question of fact upon which opinion evidence, provided it is expert, is receivable. But a finding of causal connection may be open without any medical evidence at all to support it: Nicolia v Commissioner for Railways (NSW) (1970) 45 ALJR 465, or when the expert evidence does not rise above the opinion that a causal connection is possible: EMI (Australia) Ltd v Bes [1970] 2 NSWR 238; appeal dismissed (1970) 44 ALJR 360N. The evidence will be sufficient if, but only if, the materials offered justify an inference of probable connection. This is the only principle of law. Whether its requirements are met depends upon the evaluation of the evidence.’
84 It is often difficult to distinguish between permissible inference and conjecture. Characterisation of a reasoning process as one or the other occurs on a continuum in which there is no bright line division. Nevertheless, the distinction exists.
85 Lord Macmillan in Jones v Great Western Railway Co (1930) 47 TLR 39, in the context of stating that a possibility that a negligent act caused injury was not enough, said (at 45):
‘The dividing line between conjecture and inference is often a very difficult one to draw. A conjecture may be plausible but is of no legal value, for its essence is that it is a mere guess. An inference in the legal sense, on the other hand, is a deduction from the evidence, and if it is a reasonable deduction it may have validity as legal proof. The attribution of an occurrence to a cause is, I take it, always a matter of inference."
86 After referring to this passage, Sir Frederick Jordan in Carr v Baker [1936] NSWStRp 20; (1936) 36 SR(NSW) 301 said (at 306):
‘The existence of a fact may be inferred from other facts when those facts make it reasonably probable that it exists; if they go no further than to show that it is possible that it may exist, then its existence does not go beyond mere conjecture. Conjecture may range from the barely possible to the quite possible.’
87 As Lord Wright put it in a frequently cited passage in Caswell v Powell Duffryn Associated Collieries Ltd [1940] AC 152 at 169-170:
‘Inference must be carefully distinguished from conjecture or speculation. There can be no inference unless there are objective facts from which to infer the other facts which it is sought to establish. In some case the other facts can be inferred with as much practical certainty, as if they had been actually observed. In other cases the inference does not go beyond reasonable probability. But if there are no positive proved facts from which the inference can be made, the method of inference fails and what is left is mere speculation or conjecture.’
88 The test is whether, on the basis of the primary facts, it is reasonable to draw the inference. (See eg Layton v Vines [1952] HCA 19; (1952) 85 CLR 352 at 358).
89 In my opinion, evidence of possibility, including epidemiological studies, should be regarded as circumstantial evidence which may, alone or in combination with other evidence, establish causation in a specific case.
90 Proof on the balance of probabilities, indeed on the beyond reasonable doubt standard, may be established on the basis of circumstantial evidence. As Lord Cairns said in Belhaven and Stenton Peerage [1875] 1 AC 278 at 279:
‘My Lords in dealing with circumstantial evidence, we have to consider the weight which is to be given to the united force of all the circumstances put together. You may have a ray of light so feeble that by itself it will do little to elucidate a dark corner. But on the other hand, you may have a number of rays, each of them insufficient, but all converging and brought to bear upon the same point, and, when united, producing a body of illumination which will clear away the darkness which you are endeavouring to dispel.’
91 Causation, like any other fact can be established by a process of inference which combines primary facts like ‘strands in a cable’ rather than ‘links in a chain’, to use Wigmore's simile. (Wigmore on Evidence (3rd ed) para 2497, referred to in Shepherd v R [1990] HCA 56; (1990) 170 CLR 573 at 579).
92 In the present case, the primary facts consist, in large measure, of epidemiological studies.
93 With respect to many diseases, medical science is able to give clear and direct evidence of a causal relationship between a particular act or omission and a specific injury or disease. There are, however, fields of inquiry where medical science is not able to give evidence of that character. There are cases in which medical science cannot identify the biological or pathological mechanisms by which disease develops. In some cases medical science cannot determine the existence of a causal relationship. Such a state of affairs is not necessarily determinative of the existence or non-existence of a causal relationship for purposes of attributing legal responsibility. Epidemiological evidence may be able to fill the gap. It is of particular potential utility in the field of what is often referred to as ‘toxic torts’, especially in case of diseases with long latency periods.
94 In circumstances where the aetiology of a disease is uncertain, or subject to significant scientific dispute, the Courts are not thereby disenabled from making decisions as to causation on the balance of probabilities. As Herron CJ said in EMI (Australia) Ltd v Bes [1970] 2 NSWR 238 at 242:
‘Medical science may say in individual cases that there is no possible connection between the events and the death, in which case, of course, if the facts stand outside an area in which common experience can be a touchstone, then the judge cannot act as if there were a connection. But if medical science is prepared to say that it is a possible view, then, in my opinion, the judge after examining the lay evidence may decide that it is probable. It is only when medical science denies that there is any such connection that the judge is not entitled in such a case to act on his own intuitive reasoning. It may be, and probably is, the case that medical science will find a possibility not good enough on which to base a scientific deduction, but courts are always concerned to reach a decision on probability and it is no answer, it seems to me that no medical witness states with certainty the very issue which the judge himself has to try.’
95 In Fernandez v Tubemakers [1975] 2 NSWLR 190, the plaintiff's medical witness gave evidence to the effect that the relevant trauma was a ‘possible cause’. Mahoney JA distinguished two issues - first whether the trauma was a possible cause and secondly whether it was the actual cause in the case (see also Barnes v Hay (1988) 12 NSWLR 337 at 353) - and said (at 199):
‘The question remains whether, accepting that the trauma was a possible cause of the condition, it was open to the jury to infer that, in this case, it was the actual cause of it. The evidence, or the process of reasoning, sufficient to warrant this conclusion may, again, vary with the circumstances of the case. However, before the possible cause, the trauma, can in this particular case be inferred to be the cause of the condition, the cause must be related to the condition, not merely temporally, but `sufficiently closely'.’
96 His Honour referred to the judgments in EMI (Australia) Ltd v Bes, set out the extract from Herron CJ which I have quoted above, and concluded (at 200):
‘In such a case as the present, the question would be whether the evidence showed the connection between the possible cause and the condition which occurred was sufficiently close to warrant a reasonable mind, faced with the problem of determining the question upon the evidence before it, concluding that the possible was the actual cause.’
(This passage was quoted with approval by the Full Court of the Supreme Court of Victoria in Dahl v Grier [1981] VicRp 50; (1981) VR 513 at 523).
97 In Jones v Dunkel [1959] HCA 8; (1958-59) 101 CLR 298 at 305 Kitto J said:
‘...I agree that no ground for an inference is to be found in general considerations as to the likelihood of negligent conduct occurring in the condition which existed at the time and place of the collision. One does not pass from the realm of conjecture into the realm of inference until some fact is found which positively suggests, that is to say provides a reason, special to the case under consideration, for thinking it likely that in that actual case a specific event happened or a specific state of affairs existed.’
98 The Courts must determine the existence of a causal relationship on the balance of probabilities. However, as is the case with all circumstantial evidence, an inference as to the probabilities may be drawn from a number of pieces of particular evidence, each piece of which does not itself rise above the level of possibility. Epidemiological studies and expert opinions based on such studies are able to form ‘strands in a cable’ of a circumstantial case.”

While Dr Granot initially expressed doubt as to whether the applicant suffered from malaria, the notes of the Pacific International Hospital contained within those produced by the Royal Women’s and Brisbane Hospital seem to dispel any doubt that the applicant’s account of developing malaria in Papua New Guinea is correct. The note of the hospital dated
28 August 2020 also stated that the applicant experienced severe headaches which were thought to be difficult to define. They may relate to “complications of malaria as well as alternate pathology”. However, the letter of Dr Lam dated 7 September 2020 explicitly diagnosed trigeminal neuralgia and prescribed Carbamazipine (Tegretol).
Dr Lin saw the applicant on 14 September 2020 and noted that his pain “ceased completely” on the previous day. However on 23 September 2020, the applicant complained of ongoing pain in his left cheek and temporal area overnight which interfered with his sleep. The doctor diagnosed trigeminal neuralgia.
On 14 October 2020, Dr Lin recorded that the applicant’s neuralgia pain “settled”. On 25 November 2020, the recorded another attack on 14 November which caused the applicant to attend the Bathurst Hospital. The doctor recommenced the applicant on Carbamazepine and referred him to a neurologist. As I have indicated, Dr Granot now accepts the diagnosis of trigeminal neuralgia.
Dr Granot’s opinion is underpinned by his view that the epidemiological and other scientific studies do not establish a proven connection between malaria and the onset of trigeminal neuralgia. Dr Lin also expressed the opinion that he was unsure if there was any evidence of a connection between these conditions, although he emphasised that this was “outside the scope of his practice”. The link is also questioned Dr Douglas, whose report is partially reproduced in the second report of Dr Granot, and the “absence of evidence” is noted by several of the applicant’s treating specialists whose opinions I canvas below.
On 14 January 2021, the applicant saw Dr Smail, a consulting neurologist, who ultimately provided a report bearing date 12 March 2021. Dr Smail considered a diagnosis of “atypical facial pain” stating that the duration of the applicant’s pain and its refractoriness to medication was consistent with this diagnosis. However, his preferred view was that the applicant suffered from trigeminal neuralgia.
In respect of the issue of causation, Dr Smail stated:
“The link between Mr de la Rosa’s work in PNG and the onset of his trigeminal neuralgia is difficult to prove, since there are no published case reports or literature regarding a link. Given his previous good health and lack of pain disorder prior and given the temporal relationship with the onset of the pain and his malaria, I believe that the malaria acted as a trigger for his trigeminal neuralgia.”
Dr Smail continued:
“A conceivable link can be made about a potential auto-immune basis for the onset of trigeminal neuralgia after malaria. An over-zealous immune response attacks the roots of the trigeminal nerve, inducing hyper excitable changes and leading to trigeminal neuralgia. Similar aetiology has been postulated in disorders of the viith cranial nerve, where a significant portion of Bell’s palsies have a preceding infectious trigger. In some cases a specific virus (HSB1 or VZV) can be isolated, but frequently the infection produces symptoms but is not identified.”
Dr Smail went on to say that the link between malaria and the applicant’s current symptoms was circumstantial:
“but the temporal relationship between the malaria and the onset of his symptoms (in the absence of prior pain or neurological disorder) would support a link between the two. Although I would agree with Dr Lin’s assessment that there is no described link between P. vivax malaria and trigeminal neuralgia and [sic] absence of evidence does not necessarily imply evidence of absence, particularly with rare conditions.”
On 18 February 2021 and 25 March 2021, the applicant saw Dr Mark Dexter, the Head of the Department of Neurosurgery at Westmead Hospital. He expressed the opinion that the applicant was suffering from trigeminal neuropathic pain as his pain had always been
“confined to the third and second divisions of the left trigeminal nerve”. He expressed the following opinion on causation:
“I cannot find any other cause for Mr de la Rosa’s trigeminal neuralgia. The timing of the onset of his facial pain with his diagnosis of malaria makes me believe that there is a causal relationship between his malaria infection and the onset of facial pain, but as I mentioned I do not feel that I am an expert in the treatment of malaria.”
However, the doctor also stated that he would defer to Dr Newcombe’s opinion that facial pain “can follow infection with malaria”.
On 3 March 2021, Dr Newcombe noted that there was some evidence, although tenuous, of a link between malaria and trigeminal neuralgia in the aetiological evidence. He continued:
“This showed that a small subset of patients in this review had malaria identified as a cause (0.23% in this review). Certainly the underlying pathogenesis of trigeminal neuralgia which is often thought to be due to neurovascular compression, would fit with malaria being a cause of trigeminal neuralgia due to malaria’s ability to cause vasculitis and vasculopathy. Therefore this link does make pathological sense. Certainly in this case, Mr Mercado de la Rosa had onset of a neuropathy-type headache which persisted and took on the characteristics of trigeminal neuralgia within 2 weeks of the onset of illness with malaria. This would strongly point towards malaria in this case being the cause of trigeminal neuralgia.”
On 6 October 2021 the applicant saw, Dr Laban, a neurosurgeon, who further considered whether there was any surgical solution for the applicant’s symptomatology. Dr Laban reviewed the MRI scan of the brain and skull of 25 March 2021 and concluded that while the superior cerebellar artery was seen coursing above the cisternal segment of the left trigeminal nerve “there is no neurovascular compression on either side”. He continued:
“I concur with Dr Dexter and Dr Cameron Smail’s very thorough assessments and have recommended ongoing medical treatment with Dr Smail. I would not advocate microvascular decompression and have concerns that other surgical interventions or ablative treatments may cause additional problems such as anaesthesia dolorosa. This bilateral neuropathic type trigeminal pain presumably secondary to central sensitisation can be extremely difficult to manage but hopefully will improve in time.”
On 11 July 2022, Dr Christopher Peck, who is apparently a dentist, wrote to Dr Jane Standen at Sydney Pain Specialists concerning the applicant’s review at the Michael J Cousins Pain Management and Research Centre. Relevantly Professor Peck said this:
“I informed Mr de la Rosa that I had consulted with neuropathic pain and malaria experts and while neuro-inflammation likely occurred during the acute infection, it would not have continued for this length of time. In my opinion his persistent pain is likely as a result of nervous system sensitisation, and the initial neuro-inflammation may have contributed to this. I discussed with Mr de la Rosa the biopsychological construct of pain and the need for him to learn and use self-management strategies for his pain. He is aware that medication has had limited effectiveness on his pain, and there has been no surgical procedure recommended for him.”
It can be seen that Dr Smail’s view of the medical literature is similar to that of Dr Granot’s and different to that of Dr Teychenne. However, it is also evident that each of the specialist medical practitioners above have reached a conclusion that it is likely that the applicant’s trigeminal neuralgia was caused by his malaria. It is true that the mechanism by which they believe one caused the other is not entirely uniform. Dr Smail postulates an “auto-immune basis” for the neuralgia whereas Dr Newcombe, the infectious diseases expert, believes the link relates to “malaria’s ability to cause vasculitis and vasculopathy”. While I do not pretend to completely understand the scientific basis of the postulated mechanisms, it appears likely that the opinions of Dr Laban and Dr Peck are compatible with the approach of Dr Smail. It is also true that each of these doctors emphasise the importance of a temporal connection in reaching the conclusion on causation. However, they also rely on the absence of any other likely cause.
Dr Granot, on the other hand, points to two potential causes of trigeminal neuralgia other than malaria. One of these potential causes is the removal of the applicant’s wisdom tooth on 17 September 2020. This can be dealt with shortly. Dr Granot expressed the opinion that there was medical literature to support a connection between tooth extraction and the onset of trigeminal neuralgia. But the applicant had the symptoms of trigeminal neuralgia and was diagnosed with that condition by a medical practitioner before 17 September 2020. Thus, while it is possible that the tooth extraction may have contributed in some way to the perpetuation of the applicant’s condition, it could not have been responsible for the initial onset of the condition.
Dr Granot’s primary hypothesis, however, is that the condition is caused by “direct vascular contact” of the cerebellar artery with the trigeminal nerve as demonstrated by the imagining of 21 March 2021. Dr Granot states that this is caused by a congenital abnormality. The view that the condition is congenital, however, inevitably raises the question of why it did not cause symptoms of trigeminal neuralgia until the applicant’s 34^th year. It is also inconsistent with the opinions of Dr Dexter and Dr Laban, the two neurosurgeons who investigated the applicant with a view to ascertaining whether there was any surgical remedy available for his condition.
Mr Hunt argued, of course, that the doctors in the applicant’s medical case had not considered the imaging of 21 March 2021. I do not consider that is likely. It would be extraordinary if two surgeons completely neglected a comment by a radiologist pointing out an obvious cause of the condition that they were retained to treat. Dr Laban specifically states that he reviewed the MRI scan and notes that while the cerebellar artery is seen coursing above the trigeminal nerve “there is no neurovascular compression on either side”.
Dr Dexter stated:
“The most common cause of trigeminal neuralgia in a young person is vascular compression at the root entry zone of the left trigeminal nerve, typically by an ectactic loop of the superior cerebellar artery. He has now had two MRI scans, in November 2020 and in March 2021, that showed no evidence of vascular oppression or other cause of his facial pain.”
Thus, Dr Granot’s theory is contradicted by the two neurosurgeons who investigated the issue. In the circumstances, of this case I prefer their opinions on this issue. They clearly recognised the potential for the cerebellar artery to impinge on the trigeminal nerve, investigated it, and found that, in this instance, it did not.
Once Dr Granot’s alternative causes of trigeminal neuralgia are removed, his objection to malaria as a cause loses much of its force. As always in these types of cases there are some aspects of the evidence that cannot be readily reconciled with one or other of the conclusions of the medical practitioners whose opinion the Commission chooses to accept. There is, at least, one period of month where the applicant reported that he was largely, if not entirely, asymptomatic and the applicant has on occasions complained of bilateral facial pain. Dr Granot suggests the former matter is important as it is inconsistent with a vascular cause of trigeminal neuralgia.
While the medical practitioners who have treated the applicant do not agree on the precise mechanism which gave rise to the applicant’s more recent symptoms, as I read their reports there is agreement on one critical aspect in respect causation; that the applicant developed trigeminal neuralgia as a result of his contraction of malaria. Dr Smail and Dr Peck, however, explain the applicant’s present symptoms on the basis of central nervous system sensitisation. Dr Newcombe and Dr Dexter seemed to accept the assistance of the trigeminal neuralgia as a result of vasculitis caused by the malaria. In the circumstances, it is unnecessary for the Commission to determine which theory is correct. I am impressed by the uniformity of the opinion of the four treating doctors on the initial issue of causation. Whether the neuralgia has continued to the present or caused sensitisation of the central nervous system is not an issue within the jurisdiction of the Commission.
I accept the opinions of that the applicant’s treating doctors on the issue of causation. They are consistent with the chronology of the applicant’s illness, with the absence of previous symptoms, and with the absence of any proven alternative cause of his trigeminal neuralgia. Accordingly, I reject the opinion of Dr Granot. I find on balance that as a result of contracting malaria arising out of and in the course of his employment on or about 18 August 2020, the applicant suffered the condition of trigeminal neuralgia.
Finally, the medical evidence gives rise to a medical dispute as to whether the applicant’s condition has reached maximum medical improvement. Both Dr Granot and Dr Dexter expressed the opinion that it was inappropriate to assess permanent impairment at the time of the examinations. There may also be other issues relating to the nature of the condition and its prognosis which arise on a medical assessment. Accordingly, I propose to remit the matter to the President for referral to a Medical Assessor to certify the degree of WPI, if any, as a result of the condition of trigeminal neuralgia.

[2023] NSWPIC 474

14 September 2023