Dizziness and vestibular function before and after cochlear implantation.

Vestibular problems after cochlear implantation (CI) were explored by categorizing them according to clinical course and changes in objective vestibular function. The changes in vestibular function of 62 patients (66 ears) were analyzed and vestibular symptoms were divided into three categories by their time course and nature. Etiologies were determined by analyzing the symptoms in combination with changes in objective vestibular function, measured using the caloric and/or video head impulse test. Before surgery, vestibular function was normal in 31 cases (47.0 %), unilaterally hypofunctional in 14 (21.2 %), and bilaterally hypofunctional in 21 (31.8 %). Eight cases (12.1 %) reported dizziness before surgery. A total of 18 cases (27.3 %) experienced postoperative dizziness. Ten patients experienced immediate transient dizziness (including 2 cases of benign positional paroxysmal vertigo); four experienced immediate prolonged dizziness (including 3 cases of bilateral vestibular hypofunction); and four experienced recurrent episodic dizziness (including 3 cases of suspicious endolymphatic hydrops). The sums of the maximal slow-phase velocities (SPVs) of the implanted ears were changed from 22.70 ± 17.31 to 12.55 ± 12.02°/s after implantation (p = 0.004) with very little changes in the other side (32.65 ± 24.85-31.40 ± 29.10°/s). Careful review of vestibular status is an important step, especially when deciding implantation in the only vestibular functioning ear or bilateral implantation.