Thursday, October 24, 2013

Musical Hallucinations

Stefan Evers, MD, PhD – “Musical Hallucinations”
Current Psychiatry Reports, 2006, 8:205–210

In “Musical Hallucinations,” Stefan Evers discusses several reported cases of various etiologies of musical hallucinations. The author also provides a model of categorization and opens the debate on possible pathophysiologic mechanisms. According to Evers, musical hallucinations are disorders resulting from complex sound processings in which patients hear instrumental music, songs, but also isolated sounds. Interestingly, people with damaged hearing are more likely to experience these sorts of musical hallucinations. In most cases, patients are aware of the distortive nature of their perception. The author dates the first documented case of musical hallucinations back to 1846.
Evers then proceeds to review a study conducted by German E. Berrios. In the study, called “Musical hallucinations: a historical and clinical study,” Berrios analyzed 46 cases. Of all the patients, 67% were nearly or completely deaf. Brain diseases such as tumors or strokes were discovered in 39% of all patients. Berrios noticed that musical hallucinations are more likely to affect elderly women with damaged hearing or brain diseases, but without any history of psychiatric illness.
Evers follows the review of Berrios’ work with assessment of a study done by group of  investigators lead by Matcheri Keshavan, professor of psychiatry in the Department of Psychiatry at Harvard Medical School. Of all causes for musical hallucinations, this group suggested that deafness is the most important one. According to them, brain damage relates to hallucinations to a lesser degree. As it was the case in Berrios’ study, this work showed that females are more likely to be affected by this disorder. Keshavan’s study also revealed that right-sided brainstem lesions are insignificantly more connected to this disorder then left-side lesions. Among many studies which Evers reviewed throughout his article, the most interesting is Saba and Keshavan’s. The study, performed in 1997 and called “Musical hallucinations and musical imagery: Prevalence and phenomenology in schizophrenic patients” examined 100 patients with schizophrenia. Of all these patience only 16 of them experienced musical hallucinations, and 56% of them were males. Evers, however, does not consider this study as representative because the authors observed only patients with acute auditory hallucinations.
After reviewing various studies and cases, Evers provides statistical information regarding the demographic and clinical status of all patients involved. Ages range from 20 to 90 years; 70% of all patients were females. In 27% of the cases, a localized brain lesion or a localized epileptic focus was described, but the occurrence of musical hallucinations did  not  depend  on  the  side  of  the  lesion. Exact chronicity of this disorder, however, is not clearly known. Musical hallucinations have been the focus of studies only in 0.16% of all general hospital setting examinations. When elderly subjects experiencing audiologic complaints have been studied, the frequency of musical hallucinations was 2.5%. More than one fifth of all psychiatric patients, however, have sometimes experienced musical hallucinations.
Evers then redirects his focus of attention towards categorizing the disorder’s etiologies. The first impairment he examines is Hypacusis, a hearing impairment of a conductive or neurosensory nature sometimes described as a partial deafness. In 50% of all patients, hypacusis was a predominant etiologic factor for musical hallucinations. 77% of all patients were females with the average age of 71 (± 15 years). Psychiatric disorders are factors that have been commonly considered as an important element for initiating musical hallucinations; Evers states that of all patients, depression was diagnosed in 45% of them, schizophrenia in 35%, obsessive-compulsive disorder in 10%, and neurotic symptoms in 5%. 68% of all patients were females with the average age of 51 (± 21 years). Focal brain lesions were diagnosed as the fundamental cause of musical hallucinations for a certain number of patients. In 62% of them, lesion was detected in the right hemisphere, while 38% of all patients had lesion located in the left hemisphere. 62% of all patients were female with the average age of 50 (± 16 years). In most patients, the brain lesion was vascular in nature or a tumor. In a small number of them factors such as epilepsy or intoxication were found to be the main generator of the musical hallucinations. Again, most of them were females. Evers here provides the list of chemical agents with a strong potential of fueling musical hallucinations, such as propranolol, clomipramine, marijuana, paracetamol, alcohol, and others.
According to one study, religious songs, childhood songs, and popular songs from the radio are what most patients with musical hallucinations describe. Evers recalls Nick Warner and Victor Aziz and their work “Hymns and arias: Musical hallucinations in older people in Wales;” in the study they state that in most cases older patients seem to imagine religious songs. Classical music was perceived in about 10% of the cases, while folk music in slightly higher percentage – 12%. Furthermore, a higher percentage of the perceived music was vocal than instrumental: 26% against 10%. But the most common perceived music was both, vocal and instrumental – 47%. Interestingly, 80% of patients found hallucinations to be frightening, while 20% of patients actually enjoyed them. Evers here goes back to the work of Matcheri Keshavan, who states that musical hallucinations are sometimes closely related to personal memory of patients. Keshavan has also introduced a concept called “parasitic memory,” where hallucinations can be derived from re-experiencing of stored musical experiences and stimulation of the specific neuronal circuit.
When it comes to treatment of this disorder, Evers has noted that no specific information on treatment was given so far. Single cases have been treated successfully with neuroleptic, antidepressive, and anticonvulsive drugs. The author, however, provides the results of a research performed by a group of authors under the guidance of Mark Collins. The paper “Pilot study of treatment of persistent auditory hallucinations by modified auditory input” revisits the case of a 53-year-old psychotic woman for whom listening to music was more efficient in eliminating the voices heard than medical treatment. How diverse etiologies of this disorder can be, describes the case of a 61-year-old woman who after clipping of two small aneurysms, didn’t experience any hallucinations. This case was examined in the study called “Musical hallucinations associated with seizures originating from an intracranial aneurysm” by a group of authors working with Daniel Roberts. For patients suffering from schizophrenia, antidepressive medications seemed to improve hallucination related issues. The documented reaction of a great number of patients to carbamazepine was promising.
                The author underlines that there is no clear evidence of a fundamental cause for musical hallucinations. However, hearing loss or deafness is the most discussed factor related to this disorder. Anthony Gordon in his study “Do musical hallucinations always arise from the inner ear?” discusses the inner ear disease which leads to a sort of “a hyperactive state of the ear.” On the other side, there are patients experiencing musical hallucinations without such symptoms. Brain imaging studies have shown some association with dysfunction of the temporal cortex, specifically in the left lobe. Therefore, Evers states, there is a possibility that some cases  of  musical  hallucinations are associated with focal brain damage or with associated clinical epilepsy. Memory is also an important factor when this disorder is discussed. As mentioned before, according to Keshavan and his concept of “parasitic memory,” musical perception represents a deep-rooted part of memory and can be experienced by external stimuli or simply by chance.
                Musical hallucinations are a phenomenon that has not been greatly researched and Evers’ work offers an important insight into this disorder. The fact that patients hear familiar tunes from the past supports the argument on the importance of memory in this kind of hallucinations. Recently, however, one unique form of musical hallucinations has been reported. A 60-year-old woman heard songs that she could not identify, but she realized that all of the songs she heard are familiar to her husband. This is the first case of somebody experiencing musical hallucinations with songs familiar to people from his or her environment. This is something Evers did not know at the time he made his study. Another important aspect of musical hallucinations in my opinion is related to professional musicians. In their study “Musical hallucinations in a musician,” Jason Warren and Jonathan Schott describe hallucinations of an 83-year-old musician who was able to notate his hallucinations. Their observation is focused on abnormal spontaneous activities in auditory cortical areas beyond the primary auditory cortex. But auditory hallucinations are not the only cases of musical hallucinations that patients experienced. The cases of notation hallucinations have also been reported. All patients who experienced this kind of hallucinations have some kind of musical knowledge that again stresses importance which memory has in this phenomena.

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