Pure tone audiogram and speech audiometry in patients with hereditary motor and sensory neuropathy

The goal of our work was to determine hearing thresholds in patients with hearing impairment due to hereditary motor and sensory neuropathy(HMSN I). In assessment of auditory function we used two methods: pure tone and speech audiometry. Pure tone audiometry was performed using air and bone conducted signals. Speech comprehension was defined with a test battery of monosyllabic words unknown to the patient. By comparing the results of these methods we were able to differentiate whether the hearing loss was of cochlear or retrocochlear origin. We tested 5 patients with HMSN I associated with difficulty in speech understanding. The tests showed mild to severe elevation of pure tone thresholds but no speech perception in any of tested patients. We suggest that this type of hearing impairment be due to the disorder of the auditory nerve function - a neuropathy of the auditory nerve as part of HMSN.