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Subject Area

Pediatrics

Article Type

Original Study

Abstract

Objective The aim was to evaluate the effect of cochlear implantation (CI) on the cervical vestibular-evoked myogenic potentials (cVEMP), and to examine the correlation between the different approaches of CI and vestibular insult. Background The function of the CI is to bypass the damaged or missing cochlear structures by exciting neurons in the auditory nerve directly with electrical stimuli. Although studies have shown that CI is effective and safe, the potential effects on vestibular function are of clinical concern. Patients and methods Twenty patients with bilateral sensorineural hearing loss subjected to CI surgery by two different surgical techniques (11 with posterior tympanotomy approach, nine with transcanal approach) were enrolled in the study. The patients were subjected to preoperative evaluation of the vestibular function with cVEMP. Revaluation of the vestibular function with the same test was done 2–3 months postoperatively. Results cVEMP results revealed that 7/20 (35%) had abnormal responses preoperatively. There was significant difference between cVEMP results preoperatively and postoperatively where nine patients out of 13 patients (69%) lost cVEMP response postoperatively (P = 0.004). There was no significant difference between the two different surgical approaches used during the study. cVEMP was normal postoperatively when the round window insertion technique was used (80%), while there was loss of cVEMP response postoperatively in all patients (100%) with bony cochleostomy insertion. Conclusion Vestibular system function deficit was found in 69% of CI children as measured by cVEMP postoperatively. There was no significant difference between the classic posterior tympanotomy approach and the transcanal approach regarding the vestibular deficit. Insertion of electrodes through the round window carries less harmful effects to the vestibular system (20%), than insertion through cochleostomy (100%).

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