Assessment of Horizontal Semicircular Canal and Graviceptive Perception Before and After Cochlear Implantation

Background/Objectives: Cochlear implantation (CI) effectively treats severe-to-profound sensorineural hearing loss, but its vestibular effects remain under investigation. This retrospective study assessed perioperative changes in horizontal canal function (video head impulse test, vHIT) and graviceptive perception (subjective visual vertical, SVV). Methods: Forty-three adults (mean age: 59 ± 15 years) implanted between May 2017 and July 2018 were assessed pre- and postoperatively. The prespecified primary analysis was the paired comparison of vHIT gain at 60 ms in the implanted ear, performed separately by implantation side; all other comparisons were exploratory. Results: Paired vHIT data were available for 36 of 43 participants. Gain in the implanted ear did not change after right-sided CI (n = 17; 1.52 ± 0.37 to 1.59 ± 0.63; change: +0.07, 95% CI: -0.41 to 0.56; t(16) = 0.32, p = 0.754), whereas it fell after left-sided CI (n = 19; median: 1.41 to 1.07; z = -3.02, p = 0.003); the two sides were not compared formally. Implanted and non-implanted ears did not differ postoperatively (n = 37; p = 0.116). Fourteen of thirty-six participants (38.9%) developed new ipsilateral catch-up saccades (exact McNemar p = 0.031 and 0.039). SVV deviation was 0.77 ± 0.47° and 0.92 ± 0.51° (p = 0.086). Conclusions: No significant change was detected after right-sided CI or in SVV; given the wide confidence interval and the small sample, this is not evidence of preserved function. The left-sided reduction, the newly developed ipsilateral catch-up saccades and the exploratory findings require confirmation in larger prospective studies.