Audiologic phenotype in individuals with neurofibromatosis type 1

Abstract

Neurofibromatosis Type 1 (NF1) is a common autosomal dominant multisystemic disorder. Auditory dysfunction is characteristic of Neurofibromatosis Type 2; however, some limited evidence suggested the auditory system may also be affected in NF1. One study reported patients with NF1 had elevated pure-tone thresholds and abnormal auditory brainstem response (ABRs); however, the audiologic phenotype has not been thoroughly characterized. The purpose of this study was to comprehensively describe the audiologic phenotype of NF1 and its impact on the auditory system. Forty individuals with NF1 were evaluated at the Audiology Unit of the Otolaryngology Branch, NIDCD/NIH. Results indicated hearing loss (> 15 dB HL) for the four frequency puretone average in 9(11.3%) ears, although hearing loss was present for at least one frequency in 29(36%) ears. Only 6(7.5%) ears had normal findings on all audiological measures. Of the 65(81.2%) ears with normal hearing sensitivity, other abnormal findings were consistent with cochlear dysfunction in 13(16.2%) ears, extra-axial pathology in 7(8.7%) ears, auditory neuropathy/dys-synchrony in 2(2.5%) ears, retrocochlear dysfunction involving VIII cranial nerve and/or the auditory brainstem tracts in 9(11.3%) ears. 15(18.8%) ears with abnormal ABRs findings were supported by findings on imaging results. These data confirmed that auditory dysfunction is often a complication in NF1. Health professionals should be aware of potential effects of NF1 on the auditory system.