gms | German Medical Science

Introduction: To which extent bilateral cochlear implantation may cause damage to the semicircular canal has not been examined yet. The aim of the study was to evaluate the rate of postoperative vestibular areflexia and secondly to evaluate the number of patients with dizziness after cochlear implantation.

Patients and methods: In this report the results of classical (spontaneous nystagmus, head-shaking nystagmus, positional testing, postural control test) and caloric response were obtained from 23 bilaterally implanted adult patients pre- and postoperatively.

The difference between post- and preoperative score was calculated for each patient. A positive score reflected the postoperative deterioration of vestibular function.

Dizziness in everyday life was retrospectively evaluated pre- and up to 12 months postoperatively by using the modified Stoll questionnaire on vestibular dysfunction in everyday life.

Patients: bilaterally implanted adult patients, n=23. Healthy patients in matched pairs technique, n=23. Unilaterally implanted patients, n=6.

Results: Postoperative loss of vestibular function occurred after three of a total of 38 surgeries (=7.9 %), shown by areflexia in caloric testing.

Bilateral CI patients: 13 patients showed improvement of vestibular function, 3 no change, 7 deterioration.

Results of questionnaire: bilateral CI patients: no deterioration in 18 patients (=78.3 %) preoperatively. Postoperative episodic dizziness was reported within the first seven days by eight patients (34.5 %), within the first month by three patients (=13.0 %).

Discussion: The preservation of vestibular function could not be achieved in three patients (=7.9 %). This rate is below the rate of postoperative loss of vestibular function cited in literature (30-60 %). The reason might be growing experience of atraumatic insertion of the electrode into the cochlea. Postoperative dizziness mainly occurred within the first seven days and remained at a constant level after one month. Furthermore there was no correlation between vestibular score and subjective reports of dizziness. The reason might be the compensation of vestibular dysfunction in the meantime.