Musical hallucinations in cerebrovascular disease

Introduction
Musical hallucinations (MH) are a  subset of  complex auditory hallucinations in which individuals perceive music in the absence of an external auditory stimulus. It is a rare phenomenon, first described by Ballinger in 1846, with diverse presentations from familiar childhood melodies to a simple pitch which evolved into the harmonies Robert Schumann incorporated in his sole Violin Concerto.

Views
This uncommon phenomenon has diverse etiologies, including psychiatric and neurological backgrounds, which guide its classification and methods of treatment. The pathophysiological basis of MH remains understood incompletely, potentially resulting from lesions anywhere along the auditory pathway, from the external auditory canal to the auditory cortex. The strong association between MH and hearing impairment has led researchers to hypothesize that MH represent a “release phenomenon,” in which sensory deprivation, eliminating the afferent input to the auditory sensory network, instigates spontaneous activity within a system – comparable to the Charles Bonnet syndrome, in which visual impairment precipitates the development of visual hallucinations (so called auditory Charles Bonnet syndrome), and phantom limb syndrome, in which amputees experience sensations in a limb that is not no longer there. In this paper, we report on six cases of MH in patients with cerebrovascular disease, who presented to the neurology department at the Poznan University of Medical Sciences from 2015 to 2018.

Conclusions
We discuss the findings of computed tomography and magnetic resonance imaging of six cases of MH in patients with cerebrovascular disease, and the treatment leading to its resolution. We briefly review the literature on MH in patients with cerebrovascular diseases, discussing their suggested pathophysiology, clinical presentations and response to medical treatment.