Reliability of low-frequency auditory stimulation studies associated with technetium-99m hexamethylpropylene amine...

Development of auditory stimulation tests associated with single-photon emission tomography (SPET) shows evidence of variations in perfusion related to the stimuli. Three brain SPET examinations with technetium-99m hexamethylpropylene amine oxime were performed on eight right-handed adults with normal hearing, the first one without stimulation and the other two associated with a 500-Hz/30-dB stimulation of the right ear. Temporal regions of interest covering auditory areas, as well as parietal ones (internal control), were drawn on three successive coronal slices. A cortico-cerebellar index R was calculated, and the variation in activity was defined for each subject using the ratio R poststimulation--R prestimulation/R prestimulation. A significant increase in the temporal cortex count occurred in all subjects. This increase was bilateral, except for one subject in whom it was not significant on the right side. This result recurred during the second stimulation study. Overall the response of the left temporal cortex was stronger, although the asymmetry was not significant. The asymmetry repeated itself after each stimulation. The perfusion response is globally reliable in our study. We must ascertain how sensitive this test is with regard to deaf adults and adults with normal hearing before extending its use to children.