SPET MONITORING OF PERFUSION CHANGES IN AUDITORY-CORTEX FOLLOWING MONOFREQUENCY AND MULTIFREQUENCY STIMULI

Aim: in order to assess the relationship between auditory cortex perfu sion and the frequency of acoustic stimuli, twenty normally-hearing su bjects underwent cerebral SPET. Methods: In 10 patients a multifrequen cy stimulus (250-4000 Hz at 40 dB SL) was delivered. while 10 subjects were stimulated with a 500 Hz pure tone at 40 dB SL. The prestimulati on SPET was subtracted from poststimulation study and auditory cortex activation was expressed as percent increments. Results: Contralateral cortex was the most active area with multifrequency and monofrequency stimuli as well. A clear demonstration of a tonotopic distribution of acoustic stimuli in the auditory cortex was achieved. In addition, th e accessory role played by homolateral acoustic areas was confirmed. C onclusion: The results of the present research support the hypothesis that brain SPET may be useful to obtain semiquantitative reliable info rmation on low frequency auditory level in profoundly deaf patients. T his may be achieved comparing the extension of the cortical areas acti vated by high-intensity multifrequency stimuli.