Akademik

   Also known as musical hallucinosis, auditory Charles Bonnet syndrome, and Oliver Sacks' syndrome, after the British neurologist Oliver Wolf Sacks (b. 1933). All four terms are used to denote an *auditory hallucination characterized by songs, tunes, melodies, harmonics, rhythms, and/or timbres. Phenomenologically, musical hallucinations resemble ordinary music. They are also likened to tunes that go round in the head, except for the fact that musical hallucinations have a definite perceptual quality, and that in most cases they cannot be stopped voluntarily (although some individuals report that they can alter the tempo or change the tune of their musical hallucinations at will). Sometimes a distinction is made between vocal and instrumental types of musical hallucinations. Whether the vocal type - consisting of songs, or singing, or humming voices - should be allowed to count as a * verbal auditory hallucination (VAH) is a taxonomic issue open to debate. Musical hallucinations tend to commence abruptly, but they have also been reported as developing gradually out of * tinnitus. In the latter case they are also referred to as musical tinnitus. They can be heard either continuously or discontinuously, inside or outside the head, and may be repetitive and stereotyped, or elaborate and constantly changing. Their content may be familiar or unfamiliar, but tunes remembered from childhood are often reported. Musical hallucinations can occur either in isolation, or in association with other types of auditory hallucinations (both verbal and nonverbal), or * compound hallucinations. Although historically they have been regarded as rare, it is now believed that they have merely been underreported. The first known account of musical hallucinations was published in 1846 by the French alienist Jules Gabriel François Baillarger (1806-1891). In 2004 the German neurologists Stefan Evers and Tanja Ellger were able to retrieve 132 cases in the literature. When musical hallucinations are attributed to an identifiable somatic disorder, they are referred to as symptomatic musical hallucinations. When such an underlying somatic condition cannot be demonstrated, they are referred to as idiopathic musical hallucinations. Among individuals experiencing musical hallucinations there would seem to be a marked overrepresentation of females (purportedly as high as 70 or 80%), and the elderly (mean age 62 years) with or without a clinical diagnosis of Alzheimer's disease. A history of psychiatric illness (notably mood disorder or *psychotic disorder) was found in under a quarter of the published cases. On the other hand, neurological disorders (such as space-occupying lesions, epileptic foci, and cerebrovascular disease affecting the right or left temporal lobe) were found in some 40% of cases. Musical hallucinations were described primarily in association with audiological complaints such as * hypacusia and *deafness. Other associated conditions are tinnitus, inflammatory encephalopathy, encephalitis, * Lyme disease, the use of therapeutics (such as * antibiotics, antidepressants, opioids, salicy-lates, and beta blockers), and the use of alcohol, cocaine, * hallucinogens, and other illicit substances. A case report by the French psychiatrists Jean Lhermitte (1877-1959) and Georges Parcheminey (1888-1953) indicates that musical hallucinations may also occur as a complication of electroconvulsive treatment (ECT). The neuro-physiological correlates of musical hallucinations are still obscure. The neurobiology of music suggests that the hemisphere non-dominant for language plays a key role in the processing of music, and thus perhaps also in the mediation of musical hallucinations. However, empirical evidence indicates that there is only a slight preference for the right temporal lobe. As for the pathophysio-logical mechanisms underlying musical hallucinations, it has been suggested that * deafferentiation plays a role in their mediation (hence the eponym auditory Charles Bonnet syndrome). A second hypothesis takes into account the possible role of auditory * sensory deprivation, followed by *perceptual release. This proposed mechanism is also referred to as the parasitic memory hypothesis. A third hypothesis focuses on focal epileptic seizures and focal brain lesions directly affecting a network module involved in the processing of music. It has been suggested that musical hallucinations may also play a role in musical creativity. This may have held true in the case of composers such as Joseph Haydn (1732-1809), Gaetano Donizetti (1797-1848), Maurice Ravel (1875-1937), and Bedrich Smetana (1824-1884).

   References

   Berrios, G.E. (1990). Musical hallucinations. A historical and clinical study. British Journal of Psychiatry, 156, 188-194.

   Bever, T.G., Chiarello, R.J. (1974). Cerebral dominance in musicians and non-musicians. Science, 185, 537-539.

   Coebergh, J.A.F., Shaya, M., Koopman, J., Blom, J.D. (2009). Muzikale hallucinaties. Nederlands Tijdschrift voor Geneeskunde, 153, B313.

   Evers, S., Ellger, T. (2004). The clinical spectrum of musical hallucinations. Journal ofthe Neurological Sciences, 227, 55-65.

   Hageman, G., Wagener-Schimmel, L.J.J.C., Nijhuis, I.E.M.G., Vink, A.C. (2004). Liedjes in het hoofd: Het syndroom van Oliver Sacks? Tijdschrift voor Neurologie en Neurochirurgie, 105, 26-31.

   Keshavan, M.S., Davis, A.S., Steingard, S., Lishman, W.A. (1992). Musical hallucinations: A review and synthesis. Neuropsychiatry, Neu-ropsychology and Behavioral Neurology,5, 211-223.

   Lhermitte, J., Parcheminey, G. (1943). Sur une complication exceptionnelle de l'électro-choc: l'hallucinose musicale. Revue Neurologique, 75, 37-38.