Cochlear Implant Surgery and the Risk of Falls in an Adult Population

Interaction of Hearing and Balance

There is increasingly assumed that, in addition to visual, vestibular and somatosensory afferents, hearing also plays a role in the regulation of balance. It seems that, especially in old age, progressive hearing loss is associated with a decrease in postural control. Several studies investigated this relationship in normal-hearing people, in patients with conventional hearing aids and with implantable hearing systems, as well as in patients with vestibular disorders. Despite the inhomogeneous study situation and lack of evidence, hearing seems to interact with the balance regulation system with potentially stabilizing effect. Furthermore, insights into audiovestibular interaction mechanisms could be achieved, which could possibly be integrated into therapeutic concepts of patients with vestibular disorders. However, further prospective controlled studies are necessary to bring this issue to an evidence-based level.

Subjective visual vertical and postural control in patients following cochlear implantation

BACKGROUND

Cochlear implantation (CI) is associated with changes in the histopathology of the inner ear and impairment of vestibular function.

OBJECTIVE

The objectives of our study were to evaluate patients for clinical manifestations of space perception and balance changes before surgery, compare them with asymptomatic subjects (controls), and report changes in posturography and subjective visual vertical (SVV) during the acute post-surgery period in patients.

METHODS

Examination was performed using static posturography and the SVV measurement. We examined 46 control subjects and 39 CI patients. Patients were examined pre-surgery (Pre), 2nd day (D2) and then 14th day (D14) after implantation.

RESULTS

Baseline SVV was not different between patients and control group. There was a statistically significant difference (p < 0.001) in SVV between subgroups of right- and left-implanted patients at D2 (-1.36±3.02° and 2.71±2.36°, right and left side implanted respectively) but not Pre (0.76±1.07° and 0.31±1.82°) or D14 (0.72±1.83° and 1.29±1.60°). Baseline posturography parameters between patients and control group were statistically significantly different during stance on foam with eyes closed (p < 0.05). There was no statistically significant difference in posturography among Pre, D2 and D14.

CONCLUSIONS

CI candidates have impaired postural control before surgery. CI surgery influences perception of subjective visual vertical in acute post-surgery period with SVV deviation contralateral to side of cochlear implantation, but not after two weeks.

Perspectives: Evaluation of Older Adult Cochlear Implant Candidates for Fall Risk in a Developing Country Setting

Dizziness, vertigo, and falls are common in older adults. Data suggest that cochlear implant candidates are no different and could be argued to be at elevated risk due to the presence of hearing loss and likely vestibular involvement. Perspectives contextualizes current testing and screening paradigms for vestibular deficits and fall risk and suggests a protocol suitable for use in developing country settings.

Can hearing amplification improve presbyvestibulopathy and/or the risk-to-fall ?

Purpose

The decline of sensory systems during aging has been widely investigated and several papers have correlated the visual, hearing and vestibular systems and the consequences of their functional degeneration. Hearing loss and presbyvestibulopathy have been found to be positively correlated as is with the risk-to-fall.

Material and methods

The present study was therefore designed as systematic review (due to PRISMA criteria) which should correlate hearing amplification by hearing aids and/or cochlear implants with balance outcome. However, the literature review (Cochrane, PubMed) revealed ten paper (prospective, controlled trials and acute trials) with heterogenous patient popiulations and non-uniform outcome measures (i.e., gait analysis, questionnaires, postural stabilometry) so that no quantitative, statistical analysis could be performed.

Results

The qualitative analysis oft he identified studies showed that hearing amplification in the elderly improves spatio-temporal orientation (particularly with cochlear implants) and that the process of utilizing auditory information for balance control takes some time (i.e., the neuroplasticity-based, learning processes), usually some months in cochlear implantees.

Discussion

Hearing and balance function degenerate independently from each other and large interindividual differences require a separate neurotological examination of each patient. However, hearing amplification is most helpful to improve postural stability, particularly in the elderly. Future research should focus on controlled, prospective clinical trials where a standardized test battery covering the audiological and neurotological profile of each elderly patient pre/post prescription of hearing aids and/or cochlear implantation should be followed up (for at least 1 year) so that also the balance improvements and the risk-to-fall can be reliably assessed (e.g., by mobile posturography and standardized questionnaires, e.g., the DHI).

Influence of Cochlear Implantation on Postural Control and Risk of Falls

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.