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Deafness Claims – sound advice for borderline cases

Client Alerts08/08/2013
Disease Aware Issue 3

Mr Sutton, a 46 year old, was employed by the defendant from 1986 to the date of trial. His allegations of noise exposure covered a period of 12-14 years. Breach of duty was admitted by the defendant.

The claimant's evidence suggested levels of exposure reaching 118dB(A). Hearing protection was never provided. The claimant's ENT expert Mr Clayton suggested he had 14dB noise induced loss, plus moderate tinnitus and hyperacusis (sensitivity to loud noises).

On their face, these seem almost the perfect allegations for any claimant to succeed in a NIHL case. Insurers can therefore take a lot away from this case, which resulted in the exact opposite. It shows that borderline NIHL cannot be diagnosed on a history of noise exposure alone.

The Coles, Luttman & Buffin (CLB) Guidelines were discussed at length, demonstrating that a detailed history from the claimant should always be obtained, alongside the relevant audiometric tests to establish a supporting diagnosis.

The claim also reminds us that the burden of proof is on the claimant to prove that negligent exposure to noise has caused NIHL.

Defending the undefendable – questioning the account

The defendant did not accept that their breach of duty exposure had caused the claimant's condition. Their expert Dr Yeoh concluded that this was not due to noise, but rather ageing and constitutional factors. The claim turned on close analysis of the experts' divergent views, and on the evidence and diagnostic techniques underpinning those views.

The claimant was the first to come under scrutiny. Under cross examination, it became clear that his account of exposure, although ‘detailed’, was far from accurate. He told his expert that his exposure was mainly on the right side with occasions on the left. His audiogram revealed a notch in the left ear only. When he saw defendant’s expert, he described exposure as essentially equal in either ear [critically, after his initial audiogram results had been conveyed to him]. At the time of trial, he had decided it was 60% to the right, 40% to the left.

It also transpired that the claimant had not fully disclosed his noisy hobbies. The medical records showed that he had been a keen motorcycle rider (a potential cause of hearing loss) for some years. The court found fault with Mr Clayton for not adequately questioning the claimant.

The judge also said the claimant had been, “evasively misleading,” and had, “deliberately,” underplayed his motorcycle usage. He found the claimant to be, “unreliable as a witness on any matter of fact which is in issue.” This was more critical than simply damaging the claimant’s evidential credit. Tinnitus and hyperacusis are subjective in nature; i.e. both primary diagnosis and assessment of severity rely on the recollection of the patient.

HHJ Curran quite rightly pointed to the centrality of the, “truthfulness and reliability of the sufferer,” in considering any diagnosis. In finding the claimant to be unreliable, his account of both his tinnitus and hyperacusis were already in doubt.

Never accept a diagnosis at face value – robust application of the diagnostic criteria

At the heart of the court’s rejection of Mr Clayton's conclusions was his diagnostic method. He had never read the claimant’s statement, and failed to investigate properly the occupational history of the claimant [deemed to be mandatory by the ‘Black Book’ and the CLB Guidelines]. He accepted that Dr Yeoh took a more detailed history. He had altered his tinnitus classification (from moderate to mild) after discussing the claim with Dr Yeoh.

Mr Clayton had already accepted criticisms implicit in defendant Part 35 questions that his audiogram did not meet the CLB Guidelines in the right ear. He was also criticised for his failure to find the motorcycle references in the medical records. Mr Clayton conceded that noise exposure does not automatically equate to noise damage. He agreed that he would not have diagnosed NIHL based on Dr Yeoh’s audiogram. Despite all of this, Mr Clayton maintained a diagnosis of NIHL. The judge did not find Mr Clayton impressive as a witness.

The judge preferred the evidence of Dr Yeoh for the defendant. Dr Yeoh was found to have undertaken an impressive investigation of the claimant’s history and medical records. He established that the hyperacusis was a side effect of migraines, something documented within the records. The claimant’s sleep disturbances - said to be due to tinnitus - were actually stress related. Dr Yeoh applied the CLB Guidelines and concluded that the hearing loss present was due to age and constitutional factors. There was no NIHL.

Although Dr Yeoh’s evidence was preferred, it was not without its own controversy. One of the assessment methods used by Dr Yeoh is known as oto-acoustic emissions. This measures tiny echo waves recorded following stimulation of the cochlea. If an echo is heard, the outer hair cells are healthy. If the echo is weak or absent it suggests noise damage has occurred. The outer hair cells are usually damaged before the hearing itself deteriorates, it can be an early indication of damage. Dr Yeoh accepted that this is not a test used widely in practice. He believed that it corroborated his overall clinical opinion that there was no noise damage.

Lessons to Learn

The judgment concluded with some important notes for all NIHL cases, no matter how grim the prospects of defending it may seem:

  • The diagnosis of NIHL falls down to the balance of probabilities. The criteria for diagnosing NIHL must be robust. Dr Yeoh's analysis was detailed. His methods included several tests, not just one. He took a detailed history. Mr Clayton's methods had fallen short of those standards. Medical experts' diagnostic methods should always be considered, not just their conclusions.
  • A history of noise exposure alone cannot warrant a diagnosis of NIHL. A detailed history must still be obtained.
  • The claimant's evidence must be robust and credible. The unreliability of this claimant’s evidence cast significant doubt on his causation case.
  • The audiogram should show a clear and repeatable picture of NIHL.

Insurers should expect to see more borderline noise cases as the claimant industry seeks profitable work following the RTA reforms. The burden of proof remains the claimant's to establish that he has NIHL, and it was caused through negligent exposure. The diagnostic criteria must be robust. Exposure to excessive noise does not always lead to NIHL. Medical evidence adduced by the claimant should never be automatically accepted.