Medico-Legal Decision Making in NIHL-Related Tinnitus

Abstract

In clinical practice, tinnitus is a quite common symptom in patients with chronic acoustic trauma, and noise-induced hearing loss (NIHL). A review of the current state of knowledge on tinnitus in relation to noise exposure and hearing loss has been recently (Poole, 2010) published by the UK Health & Safety Executive. 252 publications were reviewed. The prevalence of tinnitus in populations exposed to noise at work is reported to be between 5,9% and 87,5%. Factors such as the type of subjects (e.g. health surveillance, compensation claimant), the characteristics of the noise exposure and the definition of tinnitus used apparently contribute to this variability. Several publications have shown that the prevalence of tinnitus in workers exposed to noise at work is significantly higher than in non-exposed workers. The majority of the published papers support the idea that there is an association between tinnitus and noise-induced hearing loss: the prevalence of tinnitus in workers with NIHL appears to be higher, and the workers with tinnitus have more severe NIHL. In a medico-legal context, tinnitus is mostly a subsidiary item of claim, additional to that for noise-induced hearing loss. However, tinnitus may also be the principal or only complaint, e.g. in patients with a specific and selective noise-induced dip on 4 KHz but without obvious repercussion on their social hearing. Further, as in some cases tinnitus may cause devastating (and objectivable) effects on lifestyle and ability to work, it may attract higher levels of compensation than hearing loss (Coles, 2000). In such a medico-legal situation, when e.g. the patient claims compensation for an occupational disease, potential financial advantage may be a strong motivation for feigning or exaggeration. The essentially subjective nature of tinnitus renders it very difficult to make – at least in some patients equitable medico-legal decision about presence and severity of tinnitus. This implies that assessment needs to involve a large set of parameters, combining subjective with objective items (Nieschalk & Stoll, 2002). The proposed method for medicolegally evaluating tinnitus in context of NIHL is based on a rational, echeloned progression in decision making: at each step, a quite large number of elementary (cellular) decisions, easy to make and reproducible among different experts, leads to the higher decision level. Four of such levels are worked out and formulated, with respectively 65, 12, 4 and 1 decisions. The final decision is then: accept or reject the tinnitus as a true component of the occupational disorder ( noise-induced cochlear damage ).