Effect of cochlear implantation on horizontal semicircular canal function

Abstract

The objective of this study was to assess the influence of a cochlear implant (CI) on horizontal semicircular canal (hSCC) function, to test the correlation with symptomatic vertigo and to identify possible risk factors for a postoperative vestibular impairment. In a prospective observational study design, forty-seven adult patients who had undergone cochlear implantation at Cochlear Implant Center at a tertiary referral university hospital, Munich, between 2003 and 2007, were studied. Postoperative vertigo symptoms were assessed using a questionnaire followed by a structured interview. Patients were subjected to caloric and rotational chair vestibular function tests pre- and postoperatively. The CI operation was performed with a retroauricular transmastoidal approach by three different surgeons. Thirty-six implants were Cochlear Nucleus 24 devices and 11 implants were MedEl devices. Twenty-one (45%) patients reported vertigo symptoms after CI. Functional testing of the hSCC yielded valid results in 45 of the 47 patients. Thirty-two percent of patients had a substantially reduced hSCC function after CI. Responses of caloric irrigation showed a significant worsening postoperatively in the CI ears. No direct correlation between a decrease in caloric response and risk of postoperative vertigo symptoms could be established. For the criteria age, sex, implant type, surgeon, cause of deafness, petrous bone CT findings and preoperative vertigo, there were no significant differences between the patients with and the patients without postoperative vertigo. Besides morphological changes, a cochlear implantation also causes functional damage of vestibular parts of the labyrinth. Our study showed a significant worsening of the caloric response. However, this alteration did not lead to vertigo complaints in all patients. It is therefore presumed that additional damage to sensory or visual afferents and central vestibular compensatory mechanisms play a role.

Short-Term Risk of Falling after Cochlear Implantation

“…Presumably, in other studies patients might have accommodated to whatever balance ability they were left with following surgery and might not accurately recall their more acute symptoms immediately after surgery. The finding that subjective and objective changes did not correlate well is consistent with previous observations that end-organ function is only poorly correlated with subjective impressions of balance in both cochlear implant patients as well as others Krause et al, 2009Krause et al, , 2010Mbongo et al, 2007].…”

“…Previous estimates of subjective imbalance after cochlear implantation have ranged from about one third to three quarters of implantees [Enticott et al, 2006;Fina et al, 2003;Krause et al, 2009Krause et al, , 2010Steenerson et al, 2001], although one article did report an improvement in subjective balance after surgery [Buchman et al, 2004]. One reason for our estimate being at the higher end of previously reported rates may be that we collected data within 2 weeks of surgery, whereas other studies included data from subjects tested over months to years postoperatively.…”

“…Cochlear implantation can cause damage both to the semicircular canals [Buchman et al, 2004;Enticott et al, 2006;Filipo et al, 2006;Kluenter et al, 2010;Krause et al, 2009Krause et al, , 2010Migliaccio et al, 2005], and the otolith organs Krause et al, 2010;Melvin et al, 2009]. Comparatively few studies have considered the effect of cochlear implantation on postural stability, which is the outcome variable most important to patients [Buchman et al, 2004;Kluenter et al, 2009Kluenter et al, , 2010.…”

Association between Hearing Loss and Vestibular Disorders: A Review of the Interference of Hearing in the Balance

“…Besides morphological changes, a CI also causes functional damage of vestibular parts of the labyrinth, but these findings did not lead to vertigo complaints. Other senses as visual afferents and central vestibular compensatory mechanisms play a role in order to the patient stay asymptomatic [23].…”

Dynamic Postural Stability and Hearing Preservation after Cochlear Implantation

“…Possible underlying mechanisms may include direct trauma caused by electrode insertion, acute serous labyrinthitis, reaction to a foreign body, endolymphatic hydrops, and electrical stimulation [Katsiari et al, 2013;Ibrahim et al, 2017]. Multiple studies have demonstrated damage to the semicircular canals [Buchman et al, 2004;Migliaccio et al, 2005;Enticott et al, 2006;Filipo et al, 2006;Kluenter et al, 2009Kluenter et al, , 2010Krause et al, 2009Krause et al, , 2010 and otolith organs [Basta et al, 2008;Melvin et al, 2009;Krause et al, 2010]. A recent review showed a significant negative effect on the results of caloric as well as vestibular-evoked myogenic potential tests [Ibrahim et al, 2017].…”