Keoghs Insight

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Terry Zindi

Terry Zindi

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No cause for alarm

AWARE15/08/2014
Disease Aware Issue 5

The link between exposure to excessive levels of noise and noise induced hearing loss is well established. A claimant often notices his hearing loss many years after noise exposure ceased. In many cases he will say that he only noticed his loss very recently, almost inevitably less than three years before proceedings were issued.

This is explained by the fact that noise induced hearing loss develops insidiously. It is often only when presybacusis (natural age related loss) is added to noise damage that it becomes apparent. Whilst the noise damage is complete by the time the noise exposure ceases, the added effect of the different causes of the hearing loss leads to the presentation of symptoms.

Can the same be said of tinnitus? Does that condition also occur insidiously, or would one expect it to arise at or around the time that the damage is complete for it to be attributable to noise?

Tinnitus and its attribution

The British Tinnitus Association defines tinnitus as: “the perception of sound in the absence of an external auditory stimulation. Often referred to as ‘ringing in the ears’ it is most commonly experienced as a high pitched noise sometimes having a mechanical, electrical or musical quality.”

Tinnitus causes real suffering. This is reflected in higher levels of damages awarded in cases involving tinnitus.

There are many different causes for tinnitus including noise damage, but it can also occur idiopathically. About 10% of the population suffers from constant mild tinnitus. Most of those individuals are unlikely to have been exposed to excessive levels of noise. The risk of developing tinnitus increases with age, and the cause is often unknown. So, can excessive noise which took place many years previously result in a recent presentation of tinnitus?

The short answer is that we do not know. There is a distinct lack of scientific evidence to say either way. Yet, for many years medical experts, often unchallenged, have typically included a section in their medical reports to say that the tinnitus of which a claimant complains is due to the same factors as a claimant’s hearing loss.

The traditional school of thought is that of Professor Coles in a chapter he contributed to Scott-Brown’s Otolaryngology. He says that hearing loss is the major contributor to tinnitus and that tinnitus is usually caused by whatever caused the hearing loss. It follows that, much like hearing loss, it is not until the level of the loss reaches a certain level that the tinnitus becomes apparent. However, this view is unsupported by any specific evidence.

The contrary view is that put forward by Eggermont JJ in Pathopyhsiology of tinnitus (2007). This used studies in animals which suggested that the onset of tinnitus can be delayed following damage, but only for a few days after the damage occurred. If this applies in humans one would expect that noise induced tinnitus would be noticeable around the time noise exposure ceases. Tinnitus appearing many years after exposure ceased would likely be due to some other cause.

Tinnitus is entirely a subjective condition. A claimant who complains of tinnitus is aware that this will increase the value of his claim. It may actually be the case that there will never be good evidence to prove legal causation in tinnitus claims.

The same concerns that exercise defendants in claims for lung cancer and carpal tunnel syndrome, can be applied in claims for late onset tinnitus. It is for a claimant to prove his case on the balance of probabilities. Despite this, medical evidence in these claims often goes unchallenged. There is greater consensus that moderate or severe tinnitus develops at the time of exposure, not subsequently.

In respect of tinnitus, the Black Book states: “For those who have moderate or severe tinnitus, certain criteria should be met before additional disability is apportioned. Noise induced permanent tinnitus should start at or about the time of exposure to noise (i.e. within one year of the cessation of exposure). Tinnitus that starts more than one year after the removal from a noisy environment is unlikely to be related­ to noise. In view of the high prevalence of tinnitus in normal populations, tinnitus due to age related hearing loss and tinnitus of unknown origins should be considered as possible causes of the tinnitus. The complaint of tinnitus should be medically documented prior to any compensation claim. If no previous complaint has been made, adequate reason for this should be given.”

In addition to these comments, and in relation to a severe grading of tinnitus, McCombe et al state: “there should be documentary evidence of the complaint being brought to the general (or other) medical practitioner (prior to any legal claim).”

In cases of moderate or severe tinnitus said to have developed many years after exposure has ended, such cases should be repudiated immediately - especially where there is no recorded complaint within the medical records. However, given the lack of scientific data supporting it, the general attribution to noise of late onset mild tinnitus is something that ought not go unchallenged.

The same concerns that exercised the court in Wilsher v Essex Health Authority 1988 should, arguably, concern the court in cases of late onset tinnitus. Where there are competing factors that could all cause the same condition and medical science cannot determine which is the cause in fact, then causation is not established.

Why is this relevant?

A quick glance at the most recent edition of the Judicial College Guidelines provides some answers. The following are some of the brackets for the appropriate level of damages given for hearing loss and/or slight - mild tinnitus:

  • Slight hearing loss without tinnitus or slight tinnitus without hearing loss: £5,665
  • Slight or occasional tinnitus with slight hearing loss: £5,940 - £10,175
  • Mild tinnitus with some hearing loss: £10,175 - £12,100

Tinnitus can result in significant increases in damages. When multiplied across the number of NIHL claims currently presented, this can result in significant increases in damages and therefore cost to the insurance industry. Defendants should make a two-pronged attack on claims involving late onset tinnitus.

If the tinnitus is late onset, it should not be noise related. If the onset of the tinnitus is shown to be many years earlier, limitation becomes an issue.

Practical considerations

The following approach should be considered in late onset tinnitus cases:

  • Question the claimant as to the date of onset of both the hearing loss and the tinnitus
  • Ask the expert why he considers the tinnitus is noise related, whether tinnitus can be due to any other causes and ask for evidence supporting his view
  • Ask the medical expert how he can state that the claimant would not fall within the category of individuals who would develop slight or mild tinnitus in any event
  • Consider whether the answers lead to a potential limitation defence
  • Consider making offers for the hearing loss only and not for tinnitus
  • Can tinnitus be apportioned?

The JC guidelines appear to deal with tinnitus as an indivisible disease. Ross Coles has suggested it is divisible. Where the element of NIHL comprises only a small proportion of the overall hearing loss, arguments should be raised regarding the effect and amount of tinnitus that can be attributed to the NIHL and whether the tinnitus would have occurred in any event. Principles of de minimus may apply. This is an area of law that should be tested further, with clarification provided as to the correct approach by the higher courts. Currently however, claims involving tinnitus should bear further scrutiny. There is potential to make significant savings for insurers and defendants.