Word deafness after resection of a pineal body tumor in the presence of normal wave latencies of the auditory brain stem response

We studied the case of a 48-year-old woman who had resection of a pineal bo dy tumor in terms of postoperative audiological function. Postoperative mag netic resonance imaging disclosed partial inferior colliculi destruction an d medial geniculate body degeneration. A pure tone audiogram revealed only moderate sensorineural hearing loss, but her speech perception was totally impaired. The binaural sound localization function was also impaired. The a uditory brain stem response (ABR) showed waves I, III, and V to have normal latencies. The amplitude of wave III was larger than that of wave V. These results support the view that the waves of the ABR are elicited from multi ple sources in the auditory brain stem nuclei and tracts. This case suggest s a substantial role for the inferior colliculus and medial geniculate body in the processing of speech perception and sound localization.