Acoustic Stapedial Reflex Test Modification in Ears with High Static Admittance and Asymmetric Hearing Loss: A Case Study

Abstract

Patients with high peak compensated static acoustic admittance (Y_tm) tympanograms often have normal-appearing audiometric presentations. However, this tympanometric condition may render acoustic stapedial reflex (ASR) thresholds immeasurable because of fluctuating ear canal pressure and responselike artifacts obtained irrespective of the stimulus level. There is a paucity of information in the literature about this responselike artifact and a potential technical modification to manage it. Here we describe for the first time the use of the ASR test modification with a case of bilateral high peak Y_tm tympanograms and audiometrically determined uniunilateral sensorineural hearing loss in the left ear with concerns about retrocochlear pathology. Standard audiologic procedures were completed along with a modified ASR test, and distortion-product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) testing. Fluctuating ear canal pressure prevented reliable acoustic reflex measurements. After adding positive pressure to the ear canals relative to the tympanometric peak pressure, ipsilateral ASRs were present but elevated, yet more consistent with pure-tone audiometry. Offsetting ear canal pressure may be a useful clinical modification for ASR testing in cases of high peak Y_tm tympanograms.