Is musical hallucination an otological phenomenon? a review of the literature.

Abstract:

BACKGROUND: Musical hallucination is the subjective experience of hearing music, or aspects of music, when none is being played, and as such is a disorder of the processing of complex sounds. OBJECTIVE OF REVIEW: To determine the extent to which the otological system is responsible for musical hallucination, and to evaluate approaches to clinical management. TYPE OF REVIEW: A review of all studies and literature reviews pertaining to musical hallucination, supplemented by inclusion of informative case reports. SEARCH STRATEGY: A systematic search of multiple databases carried out on 22nd March 2009 was complemented by referral to the reference lists of included manuscripts. RESULTS: Although not always troublesome in itself, musical hallucination can be a marker of underlying pathology in the ear or brain, or indicate obsessive-compulsive traits or social isolation, and is likely to be clinically underreported. Associations have been reported with hearing loss, female gender, social isolation and being over 60 years of age, although it is rare even in this group, and these may well not be independent risk factors. Robust comparative analysis of these factors with controls has yet to be undertaken. Underlying causes include neurovascular pathology, psychiatric disorders and opioid medications, however these are absent in the majority of cases. CONCLUSIONS: This review supports the proposal that the otological system plays a role in the pathogenesis of musical hallucination. Hearing impairment may act as an initiating factor, and the primary dysfunction is overactivity of auditory association cortex, although an impairment of higher-level inhibition does also seem necessary. Once underlying sinister causes have been excluded, first line treatment should be explanation of the condition and optimisation of hearing. Medications have a role only in selected patient groups.