Short-Term Risk of Falling after Cochlear Implantation

Abstract

Cochlear implantation is a highly effective intervention for hearing loss, but insertion of an implant into the cochlea is often accompanied by loss of residual hearing function. Sometimes, postoperative testing also shows loss of function in the semicircular canals or otolith organs. The effect of this loss on equilibrium, particularly in the short term following surgery, and the risk of falling due to this loss is unknown. We prospectively measured balance in 16 consecutive adult cochlear implant patients before and 2 weeks after surgery. Subjects stood on a foam pad with eyes closed, feet together and arms at the side. The length of time over which this posture could be maintained was recorded up to a maximum value of 30 s indicating normal performance. Ten of 16 subjects reached a maximal time on preoperative testing. Nine of 16 subjects lost balance function after surgery. Four of the 10 subjects with normal preoperative balance function lost function. Subjects older than the age of 60 were more likely to lose balance function than younger subjects. We used previously published values relating balance performance on foam to risk of falling to calculate the fall risk among our subjects. The relative risk of falling increased after surgery by more than threefold in some patients. Imbalance after cochlear implantation may be much more common, particularly in the short term, than previously appreciated. This imbalance is accompanied by an increased risk of falling in many patients. Careful preoperative counseling before implantation and postoperative therapeutic intervention to improve comfort and reduce the chance of falling may be warranted, particularly in patients at a risk for injuries from falls (level of evidence: 2b). i 2014 S. Karger AG, Basel

The effect of hearing aids on postural stability

“…Despite quantitative improvements in balance, none of our participants reported a subjective improvement when wearing their hearing aids either before or after our testing session. This is consistent with previous work showing a poor correlation between subjective and objective measures of balance and postural stability . This finding may be particularly important because it suggests that identifying patients whose balance might improve with hearing aids should not rely on the patient's own estimate of the effectiveness of amplification on balance.…”

“…A published abstract consisting of a case study of a patient with single‐sided deafness reported that postural sway was reduced when the implant was turned on . Although these studies are suggestive of a benefit due to cochlear implantation, it is important to recognize that balance may actually worsen, at least temporarily, presumably from labyrinthine trauma during to the surgical implantation procedure itself …”

“…Applying this relationship to the 12.75 dB average gain in performance seen in our participants, we could estimate an increase in risk of falling per annum by a factor of 1.68. The same database has been used to correlate performance on the Romberg on foam test to the risk of falling . According to that relationship, the mean difference in performance of 8.5 seconds that we saw on the Romberg on foam test corresponds to an increased risk of falling in the unaided condition of 1.67 times the risk of falling in the aided condition.…”

Assessing Gait Stability before and after Cochlear Implantation

“…The most common symptoms are vertigo, dizziness, and imbalance [10]. The risk of falls has been found to increase in 56% of all cochlear implantees (and 40% of implantees who had normal balance prior to implantation); older implantees have also been found to exhibit worse balance than younger implantees [11–13]. Most of these complications are episodic, and some are transient [14], but researchers also point to delayed effects and possible histopathologic damage that may not present symptoms [13, 15–17].…”

Balance versus hearing after cochlear implant in an adult

“…Postoperative side effects of vertigo and imbalance occur in 34% of all CI patients 5. Stevens et al reported that the risk of falls increases postoperatively in 40% of patients who had normal balance prior to the CI and in 56% of all patients 6. Thus, these particular patients need to choose between improved hearing or balance.…”