Electrophysiological and Electroacoustic Assessment of Hearing in Individuals With Neurofibromatosis Type 1

Abstract

Background: Introduction: Type 1 neurofibromatosis occurs in 1 in every 3,000 individuals, representing 90% of cases of neurofibromatosis. Hearing impairments are not commonly described as an alteration resulting from the pathology; however, sensorineural hearing losses with retrocochlear characteristics may occur as a result of the presence of acoustic neurinomas.Objectives: To assess the electrophysiological and electroacoustic hearing characteristics of individuals with neurofibromatosis type 1. Material and methods:We assessed 15 patients, 10 females and 5 males, aged between 9 and 31 years, using the following procedures: pure tone audiometry, transient evoked otoacoustic emissions, contralateral suppression of otoacoustic emissions, and brainstem auditory evoked potentials.Results: All individuals presented auditory thresholds within normal limits. The mean amplitude of the general responses of otoacoustic emissions in the right and left ears were 11.8 and 12.8 dB, respectively; the suppression effect of otoacoustic emissions was present in 73.3% for the right ear and 66.7% for the left. For brainstem auditory evoked potentials, we obtained mean wave latencies for the right and left ears respectively of wave I: 1.83 and 1.80 ms, III: 4.08 and 4.15 ms, and V: 5.96 and 6.09 ms.Conclusions: Individuals with neurofibromatosis type 1 present auditory thresholds within normal limits, present transient otoacoustic emissions, the nonsystematic presence of the suppression effect of otoacoustic emissions and prolonged latencies in brainstem auditory evoked potentials.