Late-Onset Unilateral Auditory Neuropathy/Dysynchrony: A Case Study

Abstract

Auditory neuropathy/dysynchrony (AN/AD) typically develops early in life and is bilateral in nature. Herein, we describe an unusual finding of late-onset unilateral AN/AD based on reported case history and audiometric findings. A 64-year-old female presented with a complaint of a progressive unilateral hearing loss that had developed over the past two-three years. She underwent an extensive behavioral/electrophysiological test battery. Magnetic resonance imaging was negative for internal auditory canal mass or lesion. A unilateral notched loss centered at 1000 Hz and other findings were consistent with late-onset unilateral AN/AD: observable bilateral otoacoustic emissions and cochlear microphonics, absent middle acoustic reflexes with stimulation on the affected side, abnormal auditory brain stem response on the affected side, and poorer speech recognition than would be predicted by the audiogram. Middle-latency and long-latency evoked responses were present bilaterally, although with lower amplitudes on the affected side.