- hearing loss and hallucinations
- The association between " auditory hallucinations and severe hearing loss has been known for some time. Not unlike the " visual hallucinations within the context of"Charles Bonnet syndrome (CBS), auditory hallucinations against the background of hearing loss tend to make their debut several years after the onset of the sensory impairment. Empirical research indicates that the prevalence of auditory hallucinations in individuals with severe acquired hearing loss or deafness and a clinical diagnosis of "schizophrenia is not higher than that in hearing individuals with the same psychiatric diagnosis (50 versus 50-70%). However, the auditory hallucinations experienced by individuals with severe acquired hearing loss tend to present in the form of "compound hallucinations, comprising auditory, visual, "tactile, and/or " somatic components. Thus the prevalence rate of visual and " bodily hallucinations would also seem to lie around 50% in individuals with severe acquired hearing loss or deafness, compared with around 10% in hearing individuals with a clinical diagnosis of schizophrenia. Auditory hallucinations have also been reported by prelingually deaf individuals, but the perceptual characteristics of these 'voices' are extremely difficult to assess, and empirical research in this area is limited. At least some prelingually deaf individuals report 'voices' in the form of sign language, which can perhaps be best classified as "visual verbal hallucinations. In individuals with hearing loss associated with " tinnitus, the prevalence rate of auditory hallucinations is a full 100%. However, they typically experience " nonverbal auditory hallucinations such as ringing, hissing, a clear tone, a high-tension wire, buzzing, sizzling, whistling, humming, ticking, clicking, pounding, roaring, etc. Verbal auditory hallucinations and "musical hallucinations have been reported in association with tinnitus as well, but at much lower rates. Musical hallucinations occurring in association with moderate or severe hearing loss are sometimes referred to in the literature as the " auditory Charles Bonnet syndrome. The pathophysiology of hallucinations in the hearing impaired is as yet poorly understood. Drawing on the literature on " sensory deprivation, it has been suggested that auditory hallucinations may well be due to " deafferentiation, which involves the generation of spontaneous hallucinatory activity by sensory cortical areas which are cut off from the neurons or axons conducting afferent sensory impulses. On the other hand, the sensory deprivation experiments carried out during the 1950s and 1960s have indicated that the exposure to reduced and depatterned sensory input may lead to a variety ofhallucinations, but seldom to those of a verbal auditory nature. Although the books have not been closed on this issue, the pluriform pathogenesis of auditory hallucinations in general would seem to suggest an equally pluriform pathogenesis of these hallucinations in the hearing impaired. Meanwhile, the exceptionally high prevalence of compound hallucinations reported in the hearing impaired constitutes a veritable conundrum.ReferencesAtkinson, J.R. (2006). The perceptual characteristics of voice-hallucinations in deaf people: Insights into the nature of subvocal thought and sensory feedback loops. Schizophrenia Bulletin, 32, 701-708.Critchley, E.M.R., Denmark, J.C., Warren, F., Wilson, K.A. (1981). Hallucinatory experiences of prelingually profoundly deaf schizophrenics. British Journal of Psychiatry, 138, 30-32.Henry, J.A., Dennis, K.C., Schechter, M.A. (2005). General review of tinnitus. Prevalence, mechanisms, effects, and management. Journal ofSpeech, Language, and Hearing Research, 48, 1204-1235.
Dictionary of Hallucinations. J.D. Blom. 2010.