Assessment of the medial olivocochlear reflex in normal-hearing right-handed subjects using auditory brainstem response: a pilot study

Abstract Background Hidden hearing loss can be observed and exacerbated by noise when the medial olivocochlear bundle is lesioned. Purpose Assess the medial olivocochlear reflex (MOCR) in right-handed persons with normal hearing, using auditory brainstem response (ABR). Subjects and methods The current study included 20 normal-hearing, right-handed subjects, their mean age was 29.2 ± 7.48 years, with no history of neuro-otological diseases. ABR waves were recorded from both sides at different sound levels for all participants with and without contralateral acoustic stimulation (CAS). Results On the recording of ABR waves starting by the left ear with CAS to the right ear, there was a statistically significant lower amplitude of Wave I (at 50 dBnHL) and Wave V (at 50 and 70 dBnHL). There was a statistically significant higher suppression effect (SE) on the left than right ear in Wave I (at 50 dBnHL) and Wave V (at 60 and 70 dBnHL). There were no statistically significant differences between all participants regarding the latency and ABR threshold level with CAS and without CAS. Conclusion the current study revealed amplitude reduction of ABR waves especially Wave V, with more effectiveness of the MOCR suppression effect on the right than the left ear.