Vestibular modifications after cochlear implant activation

BACKGROUND Cochlear implantation (CI) is an important rehabilitation tool for patients with hearing defects. The increase of this surgery has made it necessary to identify side effects and complications. Vertigo has a high impact on the quality of life, affecting from 2% to 60% of patients who have undergone surgery. Aim of this study was to evaluate the vestibular assessment before surgery and 1 month after the activation of a cochlear implant. METHODS Ten patients undergoing cochlear implant were recruited. Pure Tone Audiometry, Video Head Impulse Test, caloric test stimulation and static stabilometry were administered before the surgical act and after 4 weeks after the activation of a cochlear implant. A CT scan was performed as standard preoperative exam. RESULTS Nobody complained of dizziness or showed spontaneous nystagmus after surgery. The auditory threshold did not show statistically significant variations after CI (P=0.087). The vestibulo-ocular reflex gain values showed an improvement after surgery, without statistically significant differences for all three canals. The average values of side prevalence did not differ before and after CI (P>0.05). A non-significantly growing trend in the values of oscillation with closed eyes was found. CONCLUSIONS CI has a low rate of complications, including the onset of vertigo. The presence of asymmetric vestibular function before surgery can influence the choice of the side to be implanted, to avoid leading bilateral vestibular damage. More studies are necessary, with more homogeneous cases and methods, to estimate the probability of occurrence of this disorder. A vestibular assessment should be mandatory for candidates to the cochlear implant.