The Reversed Ipsilateral Acoustic Reflex: Clinical Features and Kinetic Analysis

Objective - The reversed ipsilateral acoustic reflex (RIAR) has been the subject of few studies in the past literature and the nature of this "reflex" response is not yet completely understood. It can be observed in different diseases, all of which result from inactivity of the stapedial reflex (SR). We aimed to investigate the occurrence of the RIAR in different diseases. Material and methods - An extensive clinical investigation of the RIAR was carried out. Results - The RIAR was found to be present in 100% of ears lacking an effective SR arc. Its amplitude is modulated by the air pressure level in the external ear canal whilst its sign is constantly positive and never reverses. Conclusion - Kinetic analysis of the RIAR suggests the existence of a single underlying phenomenon while the interaction of the RIAR with the SR may explain the complex morphology frequently observed in the normal ipsilateral acoustic reflex.