Acta Neuropsychiatrica 2008: 20: 91–95 All rights reserved DOI: 10.1111/j.1601-5215.2007.00255.x # 2008 The Authors Journal compilation # 2008 Blackwell Munksgaard ACTA NEUROPSYCHIATRICA Case report Musical hallucinosis: case reports and possible neurobiological models Mocellin R, Walterfang M, Velakoulis D. 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 Ômusical 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. Ramon Mocellin 1,2 , Mark Walterfang 1,2 , Dennis Velakoulis 1,2 1 Neuropsychiatry Unit, Royal Melbourne Hospital, Parkville, Melbourne, Victoria, Australia; and 2 Melbourne Neuropsychiatry Centre, University of Melbourne, Parkville, Melbourne, Victoria, Australia Keywords: auditory; deafness; hallucinations; hallucinosis; musical Ramon Mocellin, Level 2, John Cade Building, Royal Melbourne Hospital, Victoria 3050 Australia. Tel: 161 3 93428750; Fax: 161 3 93428483; E-mail: ramon.mocellin@nh.org.au Introduction Music appears to be a ubiquitous human experi- ence extending across cultures and throughout history it may have even predated language. As the experience of both the production and perception of music is closely allied to emotions, memories, fantasy and imagery, it is not surprising that some disorders of perception involve music. Musical hallucinosis (MH) can be defined as the perception of music without the presence of an ex- ternal musical stimulus in which the subject main- tains insight. It is often reported in elderly populations with acquired deafness (1). Although such experiences may result in the diagnosis of psychiatric illness, careful investigation will often reveal focal or diffuse central nervous system lesions. The authors will describe three cases in which MH were prominent and review the current understand- ing of the neurobiological basis of this phenomenon. Case 1 The first patient was an 82-year-old married woman residing in an isolated farmhouse with her husband. She had a past medical history of hypertension and mild bilateral sensorineural deafness for some years. She was not prescribed any medications, did not smoke and never drank alcohol. There was no past psychiatric history or any significant family history. She described a 2-year history of hearing music not experienced by others. Initially, she contacted the police to complain of loud music played by her neighbours. She also insisted her husband drive around the district searching for the source of the music. However, she soon began to feel her experiences were Ôtricks of her imagination’. At this time she sought medical assistance. The content of the hallucinations included familiar songs or hymns, often sung by choir-like male and female voices and accompanied by orchestral music. They could also consist of simple repeated sung phrases such as ÔI love you’. The songs could be initiated by the patient thinking of a song. At times they could echo her thoughts. They never took the form of commands and were never derogatory. She was not distressed by these experiences and enjoyed the songs during the day but they often disturbed her sleep and were worse 91