Visual-olfactory hallucinatory synesthesia: The Charles Bonnet Syndrome with olfactory hallucinations

摘要

In the year 1760, Charles Bonnet noted that his 89-year old grandfather, who was blind from cataracts, was having visual hallucinations^ The Charles Bonnet Syndrome (CBS)1 is now a well-documented condition where patients have intricate visual hallucinations, in the absence of psychosis, after a severe decrease or complete loss of vision. The most widely accepted mechanism of CBS is the concept of denervation hypersensi-tivity. This phenomena describes how internally generated electrical impulses become "released" or disinhibited within the brain following the loss of neuronal inputs from normal external visual stimuli. These released electrical signals then synapse at sites in the visual cortex and can produce complex visual hallucinations (Burke, 2002). Similarly, sensory deprivation in other modalities can lead to hallucinations in that modality.