Post Cochlear Implantation Vertigo: Ictal Nystagmus and Audiovestibular Test Characteristics

ObjectiveTo investigate ictal nystagmus and audiovestibular characteristics in episodic spontaneous vertigo after cochlear implantation (CI).Study DesignRetrospective and prospective case series.PatientsTwenty-one CI patients with episodic spontaneous vertigo after implantation were recruited.InterventionsPatient-initiated home video-oculography recordings were performed during one or more attacks of vertigo, using miniature portable home video-glasses. To assess canal and otolith function, video head-impulse tests (vHITs) and vestibular-evoked myogenic potential tests were conducted.Main Outcome MeasuresNystagmus slow-phase velocities (SPVs), the presence of horizontal direction-changing nystagmus, and post-CI audiovestibular tests.ResultsMain final diagnoses were post-CI secondary endolymphatic hydrops (48%) and exacerbation of existing Meniere's disease (29%). Symptomatic patients demonstrated high-velocity horizontal ictal-nystagmus (SPV, 44.2 degrees/s and 68.2 degrees/s in post-CI secondary endolymphatic hydrop and Meniere's disease). Direction-changing nystagmus was observed in 80 and 75%. Two were diagnosed with presumed autoimmune inner ear disease (SPV, 6.6 degrees/s and 172.9 degrees/s). One patient was diagnosed with probable vestibular migraine (15.1 degrees/s).VHIT gains were 0.80 +/- 0.20 (lateral), 0.70 +/- 0.17 (anterior), and 0.62 +/- 0.27 (posterior) in the implanted ear, with abnormal values in 33, 35, and 35% of each canal. Bone-conducted cervical and ocular vestibular-evoked myogenic potentials were asymmetric in 52 and 29% of patients (all lateralized to the implanted ear) with mean asymmetry ratios of 51.2 and 35.7%. Reversible reduction in vHIT gain was recorded in three acutely symptomatic patients.ResultsMain final diagnoses were post-CI secondary endolymphatic hydrops (48%) and exacerbation of existing Meniere's disease (29%). Symptomatic patients demonstrated high-velocity horizontal ictal-nystagmus (SPV, 44.2 degrees/s and 68.2 degrees/s in post-CI secondary endolymphatic hydrop and Meniere's disease). Direction-changing nystagmus was observed in 80 and 75%. Two were diagnosed with presumed autoimmune inner ear disease (SPV, 6.6 degrees/s and 172.9 degrees/s). One patient was diagnosed with probable vestibular migraine (15.1 degrees/s).VHIT gains were 0.80 +/- 0.20 (lateral), 0.70 +/- 0.17 (anterior), and 0.62 +/- 0.27 (posterior) in the implanted ear, with abnormal values in 33, 35, and 35% of each canal. Bone-conducted cervical and ocular vestibular-evoked myogenic potentials were asymmetric in 52 and 29% of patients (all lateralized to the implanted ear) with mean asymmetry ratios of 51.2 and 35.7%. Reversible reduction in vHIT gain was recorded in three acutely symptomatic patients.ConclusionHigh-velocity, direction-changing nystagmus time-locked with vertigo attacks may be observed in post-CI implant vertigo and may indicate endolymphatic hydrops. Fluctuating vHIT gain may be an additional marker of a recurrent peripheral vestibulopathy.