Article
Vestibular function disorders after cochlear implantation
Search Medline for
Authors
Published: | July 23, 2012 |
---|
Outline
Text
Introduction: The cochlea and the vestibular organ are anatomically and functionally very closely related. Therefore interventions in the inner ear, like the cochlear implantation (CI), can affect the vestibular function. Histological studies have shown changes primary in the otolith organs. Objective of this study was to investigate the vestibular function after implantation regarding horizontal semi-circular canal function and otolith organ function.
Material and Methods: Between 2006 and 2011 seventy one adult candidates for cochlear implantation were included in this prospective clinical study. The average age was 55 years (SD 19 years) and 55% were male, 45% female. Almost half of the patients were implanted on the right side (56%). Patients underwent vestibular function tests pre- and postoperatively including caloric irrigation of the horizontal semi-circular canal, vestibular-evoked myogenic potentials and subjective visual vertical.
Results: The analysis of the vestibular function tests showed a significant deterioration after CI mainly in the horizontal semi-circular response and in the sacculus function. 55% of the patients with preoperative normal (n=29) semi-circular function showed a decrease or a loss after implantation. Almost half of the patients (44%, n=28) with regular preoperative vestibular-evoked myogenic responses developed a new total loss of saccular function. In the utricular function we found a new side difference on the implanted side in 3 of 15 patients with preoperative regular function (n=17).
Conclusions: As the vestibular function tests showed, cochlear implantation has a relevant effect on peripheral vestibular function. Mainly saccular function and the semi-circular horizontal canal are affected. The utricular function tests are still limited for significant results. However no direct correlation to the risk of postoperative vertigo could be established. Candidates for cochlea implantation should always be informed about possible damage of vestibular function. New surgery techniques and new electrodes may reduce damage of vestibular receptors.