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Noise induced hearing loss: Guidelines on diagnosis

Pascoe v Ministry of Defence
28 January 2013
Torquay and Newton Abbott County Court

In this County Court claim, the judge dismissed the Claimant’s claim and in doing so addressed the application of the Coles Lutman & Buffin “Guidelines on the diagnosis for noise-induced hearing loss for medico-legal purposes” (12.4.00). Lawyers, medico-legal experts and the Court use this paper in determining whether a person has suffered noise induced hearing loss for which compensation is payable.

Facts

The Claimant was employed by the MOD from 12th November 1979 until 5th April 1987 as a plumber at Her Majesty’s Dockyards, Devonport. At no time during the 7 year period was the Claimant provided with any hearing protection, or advised of the need to wear it, and breach of duty was admitted by the MOD. The Claimant claimed damages for noise induced hearing loss, which he alleges he sustained by reason of the breach of duty. What was in issue was whether the loss claimed, or any of it was caused by the breach of duty.

When the Claimant was first employed in 1979 his hearing was tested and there was no evidence of significant hearing loss, except for a pattern of right-sided minimal high frequency notching which was not due to noise damage, but was idiopathic in nature. The Claimant’s hearing was not tested in April 1987, when he left employment with the MOD, but was tested again in 1992. The 1992 test indicated that there was significant hearing loss in both ears, but only at a frequency of 6kHz. At the time of the trial the Claimant was 57 and suffered from high frequency sensorineural hearing loss in both ears. Interestingly, the later audiograms showed:

  • Between 1992 and 2005 no deterioration on the right, but excessive deterioration on the left between 3kHz and 4kHz;
  • Between 2005 and 2008 the right and left ear remained stable except for deterioration at 6kHz;
  • Between 2008 and 2011 there was excessive deterioration at 4kHz for the right ear and at 6kHz in the left ear.

It was accepted that some of the Claimant‟s later hearing loss was due to the aging process. The parties agreed that any hearing loss that occurred after 1992 could not have been caused by noise exposure with the MOD.

One of the issues in this case was the nature of the Claimant‟s noise exposure. It was accepted that prior to the Claimant‟s employment with the MOD in November 1979, he was not exposed to excessive noise. The Claimant initially worked in the stainless steel workshop of the Torpedo Department at the dockyard. His work involved cutting, shaping, welding and grinding stainless steel sinks and worktops. After a year the Claimant moved to the gutting and refitting of submarines. His time would be split between working in the workshop, where he would manufacture pipe work for the submarines and stripping out and refitting the submarines. It was accepted by the Court that the Claimant in his role as a plumber was exposed to both “steady state” noise and “impulse/impact” noise.

The Claimant relied upon the medical evidence of Mr.Carruth, Consultant Otolaryngologist and the Defendant instructed Dr.Yeoh, Consultant Audiovestibular Physician.

The Law

Practitioners dealing with noise induced hearing loss claims will be familiar with the seminal paper, dated 12 April 2000, “Guidelines on the Diagnosis of a Noise Induced Hearing Loss for Medico-Legal Purposes” by Coles et al. For those not familiar with this paper, lawyers, medico-legal experts and the courts rely on it in determining whether a person has suffered noise induced hearing loss for which compensation is payable. The three main requirements for the diagnosis of a noise induced hearing loss are defined as:

  • R1. High-frequency hearing impairment;
  • R2. Potentially hazardous amount of noise exposure;
  • R3. Identifiable high-frequency audiometric notch or bulge.

Four modifying factors also need to be considered:

  • MF1. Clinical picture;
  • MF2. Compatibility with age and noise exposure;
  • MF3. Robinson‟s criteria for other causation;
  • MF4. Complications such as asymmetry, mixed disorder and a conductive hearing impairment.

In this case both experts agreed that R1 and R2 were satisfied, and what was in issue was whether R3 was satisfied. The Guidelines state:

“Evidence of probable presence of noise induced hearing loss is considered to be present if there is a downward notch in the audiogram in the 3-6 kHz range that is large enough to be identifiable with a reasonable degree of confidence”.

Paragraph 7.5 states:

“Definition: A high frequency notch in the … audiogram … that is sufficiently large to be indicative of probable presence of noise induced hearing losses where the hearing threshold level at 3 and/or 4 and/or 6 kHz …is at least 10dB greater than at 1 or 2 kHz and at 6 or 8 kHz …”

Expert evidence

In this case the Claimant suffered notching at 6 kHz without any significant deterioration at 4 kHz.

Mr Carruth was of the view that even though there was no significant deterioration at 4 kHz, given the notch at 6 kHz the Coles Guidelines were satisfied and the Claimant had suffered noise induced hearing loss for which compensation was payable.

In contrast, Dr Yeoh was of the view that given the absence of significant deterioration of 4 kHz, the Claimant could not have suffered noise induced hearing loss. In cross-examination Dr Yeoh accepted that the notching at 6 kHz was Coles‟ compliant, as the Guidelines refer to notching at, “3 and/or 4 and/or 6 kHz”.

Both experts referred to other more recent academic papers on noise induced hearing loss and in particular on exposure to both “steady state” noise and “impact/impulse” noise.

Findings

Mr Recorder Harrop dismissing the Claimant’s case and preferring the evidence of Dr Yeoh found the following:

  • The Guidelines are only guidelines – this is confirmed at paragraph 7.3, “the presence of such a notch … is not pathognomic of NIHL as it is sometimes found or can be seen to develop in people with no significant noise exposure”. The Guidelines are not statute, nor even an exhaustive statement of medical opinion on the subject of noise induced hearing loss;
  • Even though a Claimant’s hearing loss may be compliant with the Guidelines it may not lead to compensation being payable as there may be other strongly adverse, or precluding other factors or diagnosis;
  • 4 kHz is the most sensitive frequency and the most common to be damaged by noise;
  • Notching at 6 kHz is not pathognomic of noise induced hearing loss and hearing loss at 6 kHz, without loss of 4 kHz was neither usual, nor typical of noise induced hearing loss.

Comment

This case is a reminder to all practitioners that in atypical cases, where there is no notching at 4khz, one should not just strictly follow the Guidelines. It is important to carefully scrutinise the audiograms and to obtain clear details of the Claimant’s noise exposure/history, differentiating between “impact/impulse” noise and “steady state” noise.

One should not only consider the Coles‟ Guidelines, but ensure that your medical expert is well versed in the other medical literature that has arisen since the paper was published in 2000.

For further information please contact Innes Ebert, Partner, Casualty team on 020 7645 9545 or at innes.ebert@dwf.co.uk or Jamie Azim, Solicitor, Casualty team on 020 7645 9501 or at jamie.azim@dwf.co.uk

By Innes Ebert

This information is intended as a general discussion surrounding the topics covered and is for guidance purposes only. It does not constitute legal advice and should not be regarded as a substitute for taking legal advice. DWF is not responsible for any activity undertaken based on this information.

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