Auditory Function and Lesions of the Pons

Abstract

IN A previous study,¹ the authors evaluated a battery of tests used to distinguish cochlear from retrocochlear lesions and showed that absence of caloric response, absence of complete recruitment, extremely low discrimination score, severe or total tone decay, and types 3 or 4 Bekesy tracings were characteristic of lesions immediately central to the cochlea. In the retrocochlear group were included four cases of brain stem lesions, and there appeared to be some significant differences between the "nerve fiber" lesions, and the small group with brain stem or "pontine" disease. In the present study, we have attempted to distinguish further between these two categories by a study of a larger group. The same battery of tests have been used: air- and bone-conduction audiometry for pure tones; auditory discrimination scores using Harvard PB lists with live voice at 30 db above speech reception threshold; binaural alternate loudness balance test for recruitment;