Influence of Cochlear Implantation on Postural Control and Risk of Falls

Abstract

Background: Cochlear implantation is an important method of hearing rehabilitation. Earlier studies have shown the influence of implantation on the vestibular system. However, until now, the effect of hearing rehabilitation with cochlear implants (CI) on postural control and body stability has not been sufficiently studied. Objective: To analyse the effect of hearing rehabilitation with activated CI and different sound inputs (music, speech text, and white noise) on postural control and risk of falls after implantation. Methods: This was a prospective clinical trial that included 33 adult patients with at least 6 months’ use of a CI (mean time after implantation = 23 months). All patients underwent a standard or geriatric (for patients >60 years) balancing deficit test protocol with a mobile posturography system (VertiGuard®) in different situations (CI deactivated/activated and different sound inputs). As the main outcome measure, the risk of falls (%) after each protocol was calculated by evaluating body sway both forward to backward and side to side (°/s). Results: With the CI deactivated, the mean risk of falls was 45.5%. After activation of the CI, there was a small decrease in the mean risk of falls, but it was statistically significant. With an additional sound input (music or speech text) this decrease was more pronounced: 42.0 and 42.4%, respectively. This effect seems to be more pronounced in older patients. Regarding the individual patients, 72% had an improvement in the risk of falls with an activated CI, and 28% had a slight deterioration. An activated CI accompanied by sound input (music) further improved the individual risk of falls. Conclusions: Compared with prior research, this study found that the risk of falls after implantation decreased over a longer time period. Furthermore, the use of a CI and different sound inputs had a positive effect on postural control. These findings support the need for optimal hearing rehabilitation, especially in elderly patients. Although this effect is relatively small, it is important to consider for further studies that rehabilitation with CI may reduce the risk of falls. While the auditory system supposedly contributes to postural control only to a small degree and the mechanism is still poorly understood, further studies with bigger samples are warranted to clarify these effects.