Musical hallucinations

Musical hallucinations fall under the category of auditory hallucinations and describe a disorder in which a sound is perceived as instrumental music, sounds, or songs. It is a very rare disorder, reporting only 0.16% in a cohort study of 3,678 individuals.

According to Oliver Sacks' Hallucinations, the first known medical report of musical hallucinations was published in 1846, by French alienist Jules Baillarger. However, the first scientific description of the disorder was reported in the early 1900s. In the last two decades, Berrios has reported case studies in 1990 and 1991 along with Keshavan et al. in 1992. Berrios concluded that confirmed diagnoses of deafness, ear disease, brain disease, advanced age and drug use are all important factors in the development of musical hallucinations. After analyzing 46 cases, Berrios found a female predominance of 80% in women over the age of 60. The study concluded that musical hallucinations were more likely to be seen in elderly women affected by deafness or brain disease than in individuals with no psychiatric illness at all.

Keshevan and Berrios were the first authors to identify classes of musical hallucinations. These classes consisted of hearing loss, coarse brain disease (i.e. tumors), epileptic disorder, stroke, and psychiatric disorder. Although no statistical analyses were performed, the authors stated that deafness was the most strongly related factor in musical hallucinations and that there was a female predominance, which could entail a genetic component.

In 73 individual cases reviewed by Evers and Ellger, 57 patients heard tunes that were familiar, while 5 heard unfamiliar tunes. These tunes ranged from religious pieces to childhood favorites, and also included popular songs from the radio. Vocal and instrumental forms of classical music were also identified in some patients. Keshavan found that the consistent feature of musical hallucinations was that it represented a personal memory trace. Memory traces refer to anything that may seem familiar to the patient, which indicated why certain childhood or familiar songs were heard.

Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) show that musical hallucinations activate a wide variety of areas in the brain including the following: auditory areas, motor cortex, visual areas, basal ganglia, brainstem, pons, tegmentum, cerebellum, hippocampi, amygdala, and peripheral auditory system.

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