BRAINSTEM AUDITORY HALLUCINOSIS

   A term used to denote a hallucinatory state characterized by * auditory hallucinations which are attributed to aberrant neurophysiological activity in the brainstem. The concept of brain-stem auditory hallucinosis is analogous to that of * peduncular hallucinosis, except for the fact that peduncular hallucinations are believed to be mainly visual in nature. Both concepts envisage the top of the brainstem and its surrounding structures as the primary source for certain types of hallucinations. Although relatively scarce, speculations about the involvement of the brainstem in the mediation of auditory hallucinations can be found in the literature from the late 19th century onwards. The first empirical study providing empirical corroboration for this thesis was published in 1986 by the American neurologists George D.Cascino and Raymond D. Adams. Cascino and Adams reported on three individuals suffering from * nonverbal auditory hallucinations in the form of buzzing, clanging, machine noises, the sound ofbells chiming, organ tones, and so on, who showed clinical, radiologic (CT), and in one case pathologic signs of lesions of the tegmentum of the pons and lower midbrain, but no signs of structural lesions in any other part of the auditory system. In all three cases the hallucinations were continuous in nature, and associated with hearing loss due to central lesions. As the authors speculate, these findings suggest that the hallucinations at hand might perhaps be best regarded as * release phenomena. As a nosological category, brainstem auditory hallucinosis is classified as a specific type of *hallucinosic syndrome. Because of its emphasis on the involvement of a specific brain structure (i.e. the pedunculus cerebri or one of its surrounding midbrain structures) it can also be classified as a * topological model of hallucinatory activity.

   References

   Cascino, G.D., Adams, R.D. (1986). Brainstem auditory hallucinosis. Neurology, 36, 10421047.