Musical Hallucination in a Patient After Cochlear Implantation

A 66-year-old woman was referred to the psychiatric service because of musical hallucinations after a cochlea implantation. The patient experienced no hallucinations before the implantation. In 2002, the patient had a sudden onset of acute deafness due to a defect of the middle right ear. In January 2003, after an additional deafness in her left ear, she had a cochlea implantation. In 2005 the patient admitted hearing music. In the beginning, the music was soft and did not interfere with her daily life. Later on, the loudness of the music increased. Finally, she heard a rhythmic humming, sometimes so loud that she could not hold a conversation with her husband. There was no mental illness known and no previous psychiatric admission or family history of psychiatric illness. The symptoms were still present when the cochlea implantation was inactive. A CT scan revealed generalized cortical atrophy but without any pathological significance. The EEG indicated muscular artifacts in the frontal lobe but otherwise presented as a normal alpha EEG without seizer potential. The patient scored an 8 on the Beck Depression Inventory (0-9 indicates that a person is not depressed). A treatment with risperidone up to 2 mg/day or olanzapine up to 10 mg did not have an effect on her symptoms. There are some case reports in the literature that suggest that mood stabilizers have an effect on musical hallucinations. But due to the medical history (cardiac arrhythmia and hepatitis C) this was not considered for possible treatment. Therefore mirtazapine was started up to 30 mg and the patient showed slight improvement. The musical hallucinations were still persistent but not as disturbing.

Musical hallucinations have been related to female sex; social isolation; 1 age; hearing impairments; 2 brain diseases (particularly epileptic foci, tumor, or stroke) affecting the nondominate hemisphere; 3 temporal lobe lesions; 4, 5 and mental disorders including depression, 2, 5 schizophrenia, 6 and obsessive-compulsive disorder. 7 Klostermann et al. 8 reviewed 32 cases in the literature, but treatment with antipsychotic medication or anticonvulsants remained unsatisfying in all cases. In single case reports neuroleptic, antidepressive, and in particular anticonvulsive drugs were successful, but no general recommendations for treatment could be made. Keshavan et al. 9 suggested that musical hallucinations derive from memory tracts, which they refer to as a concept of “parasitic memory.” Musical hallucinations are a possible result of sensory deprivation, similar to the effects of sensory deprivation in Charles Bonnet syndrome or patients with phantom limbs. Griffiths et al. 10 revealed the similarity of activation produced by musical hallucination. However it is still unknown why these memory traces are released, apparently spontaneously, in the absence of specific brain stimulation. New to this case are musical hallucinations after a cochlea implantation. Therefore, is sensory deprivation the most likely explanation?