Positional vertigo and cochlear implantation.

OBJECTIVE: To identify patients developing positional vertigo after cochlear implantation. STUDY DESIGN: Prospective study on a cohort of patients undergoing cochlear implantation. SETTING: Academic tertiary referral center. PATIENTS: The study included 70 consecutive patients who underwent vestibular evaluation before and after cochlear implantation. INTERVENTION: Medical record review. MAIN OUTCOME MEASURE: Recorded vestibular symptoms after cochlear implantation. Patients with positional vertigo were considered case subjects, whereas those without vestibular symptoms were considered case controls. RESULTS: Benign paroxysmal positional vertigo (BPPV) occurred in 8 patients (on the cochlear implant [CI] side in 7 patients, and in the other ear in 1). One patient had BPPV of the lateral semicircular canal on the implanted side, and 7 patients had BPPV of the posterior semicircular canal (on the same CI side in 6 patients, and on the opposite side in 1), which were detected and presented during the last examination. In 5 patients, the onset of symptoms varied from 7 to 130 days after implant activation; in 2 patients, the onset occurred before activation. CONCLUSION: Three different mechanisms are proposed for the occurrence of BPPV in patients with CI. The first focuses on the fall of bone dust particles into the cochlea during cochleostomy. In the second, the vibration caused by drilling the cochlea would be sufficient to dislodge otoconia into the labyrinth. The third hypothesis suggests dislodging of an otolith because of the electric stimulation. In our patients, conservative approaches have been used with a minimal invasive cochleostomy and without perilymph suction. Thus, the vibratory trauma affecting the cochlea during cochleostomy seems to play a fundamental role in the development of paroxysmal vertigo in patients with implant.