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.