[Delusion syndromes in sensory impediment--overview and model presentation]

Since Kraepelin's description of the "paranoia of the deaf" in 1915, the connection between sensory impairment and paranoid states in old age has been repeatedly confirmed. Parallels may be drawn to delusional syndromes caused or triggered by linguistic isolation, sensory aphasia and the perceptual disturbances in early schizophrenia. An overview on the different delusional phenomena in sensory-perceptual dysfunction is given, followed by a pathogenetic model proposed in analogy to the "perceptual-release" theory of hallucinations: Reduction of sensory input and blurring of afferent schemas in the perception process result in a compensatory stimulation and "release" of paranoid patterns of information processing. Consistency of perception is reestablished at the price of rigid, delusional interpretation of ambiguous social situations.