The phenomenon of musical hallucinations, in which individuals perceive music in the absence of an external auditory stimulus, has been described sparingly in the literature through small case reports and series. Musical hallucinations have been linked to multiple associated conditions, including psychiatric and neurologic disease, brain lesions, drug effect, and hearing impairment. This study aimed to review the demographics of subjects with musical hallucinations and to determine the prevalence of neurological disorders, particularly neurodegenerative disease. Through the Mayo medical record, 393 subjects with musical hallucinations were identified and divided into five categories based on comorbid conditions that have been associated with musical hallucinations: neurological, psychiatric, structural, drug effect and not otherwise classifiable. Variables, including hearing impairment and the presence of visual and other auditory hallucinations, were evaluated independently in all five groups. The mean age at onset of the hallucinations was 56 years, ranging from 18 to 98 years, and 65.4% of the subjects were female. Neurological disease and focal brain lesions were found in 25% and 9% of the total subjects, respectively. Sixty-five subjects were identified with a neurodegenerative disorder, with the Lewy body disorders being the most common. Visual hallucinations were more common in the group with neurological disease compared to the psychiatric, structural, and not otherwise classifiable groups (P < 0.001), whereas auditory hallucinations were more common in the psychiatric group compared to all other groups (P < 0.001). Structural lesions associated with musical hallucinations involved both hemispheres with a preference towards the left, and all but two included the temporal lobe. Hearing impairment was common, particularly in the not otherwise classifiable category where 67.2% had documented hearing impairment, more than in any other group (P < 0.001). Those with an underlying neurodegenerative disorder or isolated hearing impairment tended to hear more persistent music, which was often religious and patriotic compared to those with a structural lesion, where more modern music was heard, and those with psychiatric disorders where music was mood-congruent. This case series shows that musical hallucinations can occur in association with a wide variety of conditions, of which neurological disease and brain lesions represent a substantial proportion, and that Lewy body disorders are the most commonly associated neurodegenerative diseases. A future prospective study would be helpful to further delineate an association between musical hallucinations and neurodegenerative disease.
