Bone conducted vibration is an effective stimulus for otolith testing in cochlear implant patients

BACKGROUND: Treatment with a cochlear implant (CI) poses the risk of inducing a behaviorally unmeasurable air-bone gap leading to false negative absence of cervical and ocular vestibular evoked myogenic potentials (cVEMPs, oVEMPs) to air conducted sound (ACS). OBJECTIVE: To investigate VEMP response rates to ACS and bone conducted vibration (BCV) in CI patients and the applicability of the B81 transducer for BCV stimulation. METHODS: Prospective experimental study including unilateral CI patients, measuring cVEMPs and oVEMPs to ACS and to BCV, comparing response rates, signed asymmetry ratios, latencies, and amplitudes. RESULTS: Data of 13 CI patients (mean age 44 +/- 12 years) were analyzed. For the CI side, oVEMP and cVEMP response rates were significantly higher for BCV (77% cVEMP, 62% oVEMP) compared to ACS (23% cVEMP, 8% oVEMP). For the contralateral side, no difference between response rates to ACS (85% cVEMP, 69% oVEMP) and BCV (85% cVEMP, 77% oVEMP) was observed. Substantially higher asymmetries were observed for ACS (-88 +/- 23% for cVEMPs, -96 +/- 11% for oVEMPs) compared to BCV (-12 +/- 45% for cVEMPs, 4 +/- 74% for oVEMPs). CONCLUSIONS: BCV is an effective stimulus for VEMP testing in CI patients. The B81 is a feasible stimulator.