Electrophysiological Evaluation of the Auditory Nerve in Normal Hearing Patients with Absence of Stapedial Reflex

Abstract

Introduction: The stapedial reflex is a stapedial muscle contraction located in the middle ear, induced by an intense acoustic stimulus. It is expected that individuals with auditory thresholds within the normality standards have stapedial reflexes once there is integrity of the middle ear. However, the existence of normal hearing persons, with absence of stapedial reflex, has been observed, which may suggest the absence of the stapedial muscle or even the alteration of the auditory nerve (neuropathy). The AEP (Encephalic Trunk Audition Evoked Potential) is an objective and complimentary exam of hearing that evaluates the functioning of the cochleovestibular nerve. Objective: This study was carried out aiming to review the auditory nerve electrophysiological evaluation findings, through AEP, in normal hearing patients without auditory complaints and with absence of the stapedial reflex, confirmed by imitanciometry. Method: We studied 68 individuals of both sexes and aged from 18 to 30 years without auditory complaints. The procedures carried out comprised anamnesis, internal acoustic meatus inspection, threshold tonal audiometry, logoaudiometry, imitanciometry and AEP. Results: The AEP exams of the population sample showed outcomes within the normality standard with presence of wave I, III and V, with absolute latency values and interpeaks within the normality standards, which suggested integrity of the central auditory passages. Conclusion: The absence of stapedial reflexes in normal hearing patients, without auditory complaint is not sufficient by itself to diagnose the existence of auditory neuropathy and requires application of the AEP exam.

Keywords

• Electrophysiology
• Auditory diagnosis
• stapedial reflex
• Auditory neuropathy