The risk of vestibular function loss after intracochlear implantation.

Sixty patients were selected for cochlear implantation and 50 of them received an intracochlear implant (Nucleus). Vestibular function was evaluated before and after surgery using a caloric test and a velocity step test. Sixteen patients had normal or residual vestibular function before surgery, 11 bilateral and 5 unilateral; in 3 of the latter patients, the ear with vestibular areflexia was elected for implantation, which reduced the number of patients at risk for vestibular dysfunction to 13. Vestibular function was preserved in all of these patients except for 4; the risk of vestibular function loss can therefore be rated at about 31%.