Positron emission tomography of cortical centers of tinnitus

Tinnitus is associated with a wide variety of disorders in the auditory sys tem. Whether generated peripherally or centrally, tinnitus is believed to b e associated with activity in specific cortical regions. The present study tested the hypothesis that these cortical centers subserve the generation, perception and processing of the tinnitus stimulus and that these processes are suppressed by lidocaine and masking. Positron emission tomography was used to map the tinnitus-specific central activity. By subtracting positron emission tomography images of regional cerebral blood flow distribution ob tained during suppression of the tinnitus from positron emission tomography images obtained during the habitual tinnitus sensation, we were able to id entify brain areas concerned with the cerebral representation of tinnitus. Increased neuronal activity caused by tinnitus occurred predominantly in th e right hemisphere with significant foci in the middle frontal and middle t emporal gyri, in addition to lateral and mesial posterior sites. The result s are consistent with the hypothesis that the sensation of tinnitus is asso ciated with activity in cortical regions functionally linked to subserve at tention, emotion and memory. For the first time, the functional anatomy of conditions with and without the habitual tinnitus sensation was obtained an d compared in the same subjects. (C) 1999 Elsevier Science B.V. All rights reserved.