Topography of the lesion in idiopathic sudden sensorineural hearing loss

Introduction: Etiology of ISSNHL includes cessation of vascular perfusion, viral infection and cochlear membrane injury. Precise location of injury should be defined for a target-oriented treatment. Vestibular complaints in ISSNHL are hypothesized as involvement of vestibule. Vestibular complaints can be either due to involvement of inner ear or neural tract at any level. Objectives: In the present study we aimed to demonstrate involvement of vestibular organs in the absence of vestibular symptoms. It was aimed to evaluate superior and inferior vestibular neural pathways. Methods: c-vemp and o-vemp were applied to patients suffering ISSNHL without vertigo. Pure tone averages, audiogram configurations, degree of hearing loss were analyzed. Latencies of P1 and N1 waves, amplitudes of P1–N1 waves were evaluated. Asymmetrical vemp wave patterns were compared between two ears regarding difference of PTA. Results: Latencies of c-vemp waves were longer and amplitudes were smaller. o-vemp parameters were similar on both sides. Positive correlation was observed between c-vemp latencies and degree hearing loss. Conclusion: Inferior vestibular nerve pathway is affected in the absence of vertigo in ISSNHL with spared superior vestibular nerve pathway. Damage in IVN pathway correlates with degree of ISSNHL.