Musical hallucinosis: case reports and possible neurobiological models.

Objective: The perception of music without a stimulus, or musical hallucination, is reported in both organic and psychiatric disorders. It is most frequently described in the elderly with associated hearing loss and accompanied by some degree of insight. In this setting it is often referred to as ‘musical hallucinosis’. The aim of the authors was to present examples of this syndrome and review the current understanding of its neurobiological basis. Method: We describe three cases of persons experiencing musical hallucinosis in the context of hearing deficits with varying degrees of associated central nervous system abnormalities. Results: Putative neurobiological mechanisms, in particular those involving de-afferentation of a complex auditory recognition system by complete or partial deafness, are discussed in the light of current information from the literature. Conclusion: Musical hallucinosis can be experienced in those patients with hearing impairment and is phenomenologically distinct for hallucinations described in psychiatric disorders. [ABSTRACT FROM AUTHOR]