Effects of EAS cochlear implantation surgery on vestibular function

Vestibular dysfunction in pediatric patients with cochlear implantation: A systematic review and meta-analysis

Objective

Vestibular dysfunction may delay the achievement of balance and perception milestones in pediatric patients after cochlear implantation (CIM).

Methods

A strategic literature search was done following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We searched the PubMed, Medline, Embase, Web of Science, and Cochrane Library databases from inception to July 2022. Studies were included on the otoliths, semicircular canals, and balance function changes in children after CIM. Two reviewers independently assessed the level of evidence, methodological limitations, risk of bias, and characteristics of the cases. Matched pre- and postoperative vestibular functional test data, including ocular and cervical vestibular-evoked myogenic potential (oVEMP and cVEMP), caloric test, video head impulse test (vHIT), and Bruininks-Oseretsky Test 2 (BOT-2), were used to calculate the relative risk of vestibular disorders. Subgroup analyses were performed according to surgical approach, CIM device status, and etiology.

Results

Twenty studies that met the inclusion criteria were selected for the meta-analysis. We observed significant vestibular dysfunction in pediatric patients with CIM. The results showed a statistically significant increase in abnormal cVEMP response (RR = 2.20, 95% CI = 1.87, 2.58, P < 0.0001), abnormal oVEMP response (RR = 2.10, 95% CI = 1.50, 2.94, P < 0.0001), and abnormal caloric test results (RR = 1.62, 95% CI = 1.20, 2.19, P = 0.0018) after implantation. Statistically significant differences were not found in the vHIT test results of all three semicircular canals before and after the operation (P > 0.05). Regarding static and dynamic balance, we found significantly poorer BOT-2 scores in children with CIM than in the normal group (mean difference = −7.26, 95% CI = −10.82, −3.70, P < 0.0001).

Conclusion

The results showed that vestibular dysfunction might occur after CIM in pediatric patients. Some children experience difficulties with postural control and balance. Our results suggest that a comprehensive evaluation of vestibular function should be performed before and after CIM.

[Effects of cochlear implantation on vestibular function]

The literature review is devoted to the effects arising from the effect of a cochlear implant on the vestibular system. Due to the pronounced anatomical proximity and physiological interaction of vestibular receptors with the cochlea, the installation of a cochlear implant and its electrical activity are associated with an effect on the vestibular system. The analysis of the works of foreign and domestic researchers who carried out monitoring of vestibular function in patients after cochlear implantation using modern objective methods was carried out.

Changes in Vestibular Function Following Pediatric Cochlear Implantation: a Prospective Study

OBJECTIVES

Given the close interconnection between the auditory and vestibular end organs, the increasingly broad application of (bilateral) cochlear implantation (CI) in children raises concern about its impact on the vestibular function. Unfortunately, literature on this matter is inconclusive and subject to several limitations. Therefore, this study aimed to elucidate the impact of pediatric CI on the vestibular function in a large sample of children, representative for the current CI population.

DESIGN

Fifty hearing-impaired children followed in the Ghent University Hospital were included in this prospective study. Twenty-seven patients underwent unilateral CI, and 23 were bilaterally implanted (9 sequentially, 14 simultaneously), adding up to 73 implanted ears. Children's median age at first implantation was 29 (range 8 to 194) months. Vestibular assessment was scheduled on average 2.8 months (SD: 3.6) before and 4.6 (SD: 4.0) months after implantation and consisted of video Head Impulse Testing of the lateral semicircular canals, rotatory testing (0.16, 0.04, and 0.01 Hz) and cervical vestibular evoked myogenic potential (cVEMP) testing with bone conduction stimulation. Caloric testing was added in children older than 3 years of age.

RESULTS

Overall, group analysis in our sample of 73 CI-ears did not reveal any significant impact on the vestibular function, except for a significantly shortened ipsilateral N1 latency of the cVEMP responses (p = 0.027) after CI. Complete ipsilateral loss of function after implantation was seen in 5% (3/54) of all CI-ears on the video head impulse testing, in 0% (0/10) on the caloric test and in 2% (1/52) on the cVEMP, notably all patients deafened by a congenital cytomegalovirus infection.

CONCLUSIONS

The impact of CI on the vestibular function in our dataset was limited. Therefore, the many advantages of simultaneous bilateral implantation may outweigh the risk for vestibular damage postoperatively. However, the impact on the vestibular function may be dependent on various factors (e.g., etiology of the hearing loss), and the clinical outcome is still difficult to predict. Vestibular assessment remains thus an important aspect in the pediatric CI population; first because the vestibular function should be considered in the decision-making process on (simultaneous or sequential bilateral) CI and second because it is essential to reveal a possible additional sensory deficit, allowing an opportunity for rehabilitation to improve the overall outcome of these children.

Vestibular Function After Cochlear Implantation in Partial Deafness Treatment

Introduction: Cochlear implantation is a fully accepted method of treating individuals with profound hearing loss. Since the indications for cochlear implantation have broadened and include patients with low-frequency residual hearing, single-sided deafness, or an already implanted ear (meaning bilateral cochlear implantation), the emphasis now needs to be on vestibular protection.

Materials and Methods: The research group was made up of 107 patients operated on in the otorhinolaryngosurgery department: 59 females and 48 males, aged 10.4–80.2 years (M = 44.4; SD = 18.4) with hearing loss lasting from 1.4 to 56 years (M = 22.7; SD = 13.5). The patients underwent cVEMP, oVEMP, a caloric test, and vHIT assessment preoperatively, and, postoperatively, cVEMP and oVEMP at 1–3 months and a caloric test and vHIT at 4–6 months.

Results: After cochlear implantation, there was postoperative loss of cVEMP in 19.2% of the patients, oVEMP in 17.4%, reduction of caloric response in 11.6%, and postoperative destruction of the lateral, anterior, and posterior semicircular canal as measured with vHIT in 7.1, 3.9, and 4% respectively.

Conclusions: Hearing preservation techniques in cochlear implantation are connected with vestibular protection, but the risk of vestibular damage in never totally eliminated. The vestibular preservation is associated with hearing preservation and the relation is statistically significant. Informed consent for cochlear implantation must include information about possible vestibular damage. Since the risk of vestibular damage is appreciable, preoperative otoneurological diagnostics need to be conducted in the following situations: qualification for a second implant, after otosurgery (especially if the opposite ear is to be implanted), having a history of vestibular complaints, and when there are no strict audiological or anatomical indications on which side to operate.

Vestibular Preservation After Cochlear Implantation Using the Round Window Approach

Background: The development of less traumatic surgical techniques, such as the round window approach (RWA), as well as the use of flexible electrodes and post-operative steroid administration have enabled the preservation of residual hearing after cochlear implantation (CI) surgery. However, consideration must still be given to the complications that can accompany CI. One such potential complication is the impairment of vestibular function with resulting vertigo symptoms. The aim of our current study was to examine the changes in vestibular function after implantation in patients who received CI using less traumatic surgery, particularly the RWA technique.

Methods: Sixty-six patients who received CI in our center were examined by caloric testing, cervical vestibular evoked myogenic potential (cVEMP) and ocular VEMP (oVEMP) before or after implantation, or both, to obtain data on semicircular canal, saccular and utricular function, respectively. Less traumatic CI surgery was performed by the use of the RWA and insertion of flexible electrodes such as MED-EL FLEX soft, FLEX 28, and FLEX 24 (Innsbruck, Austria).

Results: Caloric response and the asymmetry ratio of cVEMP and oVEMP were examined before and after implantation using less traumatic surgical techniques. Compared with before implantation, 93.9, 82.4, and 92.5% of the patients showed preserved vestibular function after implantation based on caloric testing, cVEMP and oVEMP results, respectively. We also examined the results for vestibular function by a comparison of the 66 patients using the RWA and flexible electrodes, and 17 patients who underwent cochleostomy and insertion of conventional or hard electrodes. We measured responses using caloric testing, cVEMP and oVEMP in patients after CI. There were no differences in the frequencies of abnormal caloric and oVEMP results in the implanted ears between the RWA and cochleostomy. On the other hand, the frequency of abnormal cVEMP responses in the implanted ears in the patients who received implantation by cochleostomy was significantly higher than that in the patients undergoing surgery using the RWA.

Conclusion: Patients receiving CI using less traumatic surgical techniques such as RWA and flexible electrodes have reduced risk of damage to vestibular function.

Predictive factors of vertigo following cochlear implantation in adults

OBJECTIVES

The occurrence of vertigo after cochlear implantation surgery is one of the most common complications, and often transient. The purpose of this study was to evaluate the occurrence of vertigo after unilateral or bilateral cochlear implantation as well as to identify potential predictive factors.

MATERIALS AND METHODS

Patients who have undergone cochlear implantation and vestibular assessment pre- and postoperatively were included retrospectively. The presence of vertigo before and after surgery was noted. Postoperative vertigo duration was divided into 3 categories: immediate postoperative (less than 2 months), transient postoperative (between 2 months and 1 year), and persistent postoperative (greater than 1 year). Pre- and postoperative vestibular assessment results (caloric irrigation and VEMP tests) as well as patients' age, operated side, surgical technique for round window access, and characteristics of the electrode array were all analyzed as potential predictive factors of postoperative vertigo.

RESULTS

A total of 166 cochlear implants (137 patients) were included in the study, with a mean age of 57.5 ± 16.4 years. Of these, 36% developed postoperative vertigo, of which 19.3% was immediately postoperative. At 1 year postoperatively, 6 cases (3.6%) had persistent disabling vertigo, with 2 cases (1.2%) having no history of vertigo prior to cochlear implantation. Regarding caloric irrigation, 21% of the patients had a vestibular deficiency before surgery, and the same percentage had decreased vestibular responses. At 2 months after cochlear implantation, 31% of the patients exhibited an alteration in their vestibular test results, and 23.5% had experienced immediate postoperative vertigo. None of the factors studied (age, operated side, surgical technique, electrode array characteristics, and vestibular test alteration) correlated with the occurrence of short-term or long-term postoperative vertigo.

CONCLUSION

The occurrence of vertigo after cochlear implantation is difficult to predict by the healthcare team and may develop into an invalidating condition. Each vestibular examination performed routinely only evaluates a specific vestibular organ dysfunction. Therefore, combining several vestibular assessments tests before and after cochlear implantation can increase their sensitivity of predicting the occurrence and eventual persistence of this symptom.

The Effect of Cochlear Implantation on Vestibular Evoked Myogenic Potential in Children

Objectives/Hypothesis

We conducted this study to assess the effects of unilateral cochlear implantation (CI) on otolith function by observing the changes in ocular vestibular evoked myogenic potential (oVEMP) and cervical vestibular evoked myogenic potential (cVEMP) in children.

Study Design: Prospective case series.

Methods

The oVEMP and cVEMP elicited by air‐conducted sound in 35 children were analyzed preoperatively and at 5 days, 1 month, and 2 months after surgery.

Results

Before CI, the response rates of oVEMPs and cVEMPs were 81.4% and 91.4%, respectively. In the implanted side, oVEMPs and cVEMPs were reduced by 37.1% and 68.6%, respectively, 5 days after CI. One month after CI, oVEMPs and cVEMPs were 34.6% and 72%, respectively, with the device switched off, and 50% and 73.1%, respectively, with the device switched on. Two months after CI, the oVEMPs and cVEMPs were 36% and 80%, respectively, when the implant was turned off, and 70.8% and 75%, respectively, when the implant was turned on.

Conclusions

The study confirmed the value of VEMP testing in the clinical setting and that absent VEMPs could indicate impairment of otolith function after CI.

Level of Evidence

4 Laryngoscope, 2020

Vestibular status in partial deafness

Introduction

The hair cells of the cochlea and the vestibulum are closely connected and may be susceptible to the same noxious factors. The relationship between their function has been a continuing field of investigation. The indications for cochlear implantation have been broadened and now include the patients with partial deafness. This raises the question of their vestibular status.

Objective

The aim of the study was to investigate whether there is any difference between the vestibular function of patients with low frequency residual hearing and those with totally deaf ears.

Methods

A total of 360 ears with profound sensorineural hearing loss were analysed before cochlear implantation. The patients were divided into four groups, according to their low frequency residual hearing (Group 1 ‒ normal or slightly elevated low frequency residual hearing; Group 2 ‒ elevated threshold but still usable hearing at low frequencies; Group 3 – non-functional residual hearing; Group 4 ‒ no detectable hearing threshold within the limits of the audiometer). The patients underwent vestibular tests: cervical vestibular evoked myogenic potential, ocular vestibular evoked myogenic potential, caloric test and video-head impulse test.

Results

The rates of elicited responses in cervical vestibular evoked myogenic potential were as follows: in Group 1 (59.3 %); Group 2 (57.5 %); Group 3 (35.2 %); Group 4 (7.7 %). For ocular vestibular evoked myogenic potential the percentage of correct outcomes was: Group 1 (70.8 %); Group 2 (56.0 %); Group 3 (40.0 %); Group 4 (14.3 %). For the caloric test we counted normal responses in 88.9 % of Group 1; 81.6 % of Group 2; 57.9 % of Group 3; 53.3 % of Group 4. For video-head impulse test we also found markedly better results in Group1, followed by Group 2, and much worse in Group 3 and 4.

Conclusion

Patients with partial deafness not only have a better cochlea but also better vestibular function, which needs to be protected. In summary, the better the low frequency residual hearing, the better the vestibular status.

Early Assessment of Vestibular Function after Unilateral Cochlear Implant Surgery

Introduction: Cochlear implantation (CI) has been reported to negatively affect vestibular function. The study of vestibular function has variably been conducted using different types of diagnostic tools. The combined use of modern, rapidly performing diagnostic tools could prove useful for standardization of the evaluation protocol. Methods: In a group of 28 subjects undergoing CI, the video head impulse test (vHIT), the cervical vestibular evoked myogenic potentials (cVEMP) and the short form of the Dizziness Handicap Inventory (DHI) questionnaire were investigated preoperatively and postoperatively (implant on and off) in both the implanted and the contralateral, nonimplanted ear. All surgeries were performed with a round window approach (RWA), except for 3 otosclerosis cases in which the extended RWA (eRWA) was used. Results: The vHIT of the lateral semicircular canal showed preoperative vestibular involvement in nearly 50% of the cases, while the 3 canals were contemporarily affected in only 14% of the cases. In all the hypofunctional subjects, cVEMP were absent. A low VOR gain in all of the investigated superior semicircular canals was found in 4 subjects (14%). In those subjects (21.7%) in whom cVEMP were preoperatively present and normal on the operated side, the absence of a response was postoperatively recorded. Discussion/Conclusion: The vestibular protocol applied in this study was found to be appropriate for distinguishing between the CI-operated ear and the nonoperated ear. In this regard, cVEMP was found to be more sensitive than vHIT for revealing a vestibular sufferance after CI, though without statistical significance. Finally, the use of RWA surgery apparently did not reduce the occurrence of signs of vestibular impairment.

Effect on vestibular function of cochlear implantation by partial deafness treatment-electro acoustic stimulation (PDT-EAS)

Purpose

Although the cochlear implantation procedure does not interfere with vestibular structures directly, both the vestibulum and the cochlea share the same inner ear fluid space, and this fluid may be responsible for transferring possibly damaging forces from one to the other. The purpose of the study is to assess postoperative vestibular function after partial deafness treatment–electro-acoustic stimulation (PDT–EAS) cochlear implantation.

Methods

Fifty-five patients were included in the study (30 females, 25 males, age 11–80, mean 41.8 ± 19.35). cVEMP and oVEMP were performed preoperatively and 1–3 months after cochlear implantation. Caloric and vHIT tests were conducted preoperatively and 4–6 months after cochlear implantation.

Results

Our study shows that, based on a wide range of electrodes, use of PDT–EAS is protective in terms of preserving vestibular function. It gives a rate of saccular damage of 15.79%, utricular damage of 19.04%, and a horizontal semicircular canal response reduction of 15.79%.

Conclusions

PDT–EAS is protective in terms of preserving vestibular function. Nevertheless, it should be emphasized that the risk of vestibular damage cannot be totally eliminated even when hearing preservation techniques are adopted.

Video head impulse test relevance in the early postoperative period after cochlear implantation

BACKGROUND

Cochlear implantation (CI) is the gold standard therapy for profound or severe sensorineural hearing loss. It is a safe surgical procedure but, because of the proximity of the cochlea and vestibule, postoperative vestibular disorder may occur. Our hypothesis is that the video head impulse test (vHIT) may be a good tool to achieve a topographic diagnosis of dizziness in the early postoperative period after CI.

AIMS/OBJECTIVES

To evaluate patients with instability, imbalance and vertigo between 7 and 14 days after CI procedure.

MATERIAL AND METHODS

A total of 31patients scheduled for unilateral CI were included in this study. vHIT for horizontal semicircular canal was performed before CI and between days 7 to 14 after the surgery.

RESULTS

Six subjects had dizziness complaints after CI: instability (N = 2), imbalance (N = 2) and vertigo (N = 2). The postoperative vHIT test turned abnormal only in subjects with vertigo as compared to the preoperative vHIT test results.

CONCLUSION AND SIGNIFICANCE

vHIT is a good vestibular function test during the first 2 weeks after CI surgery when vertigo is the main complaint.

Meta-analysis of subjective complaints of vertigo and vestibular tests after cochlear implantation

OBJECTIVE

Postoperative vertigo is a common complaint after cochlear implantation, but published incidence rates differ vastly. The aim of the present study was to investigate both subjective complaints of vertigo before and after cochlear implantation and related vestibular diagnostic tests on cochlear implant candidates.

DATA SOURCES

We performed a systematic literature search according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement in PubMed, Cochrane Register, and EMBASE.

REVIEW METHODS

We presented 116 eligible studies investigating subjective complaints of vertigo after cochlear implantation and/or related vestibular diagnostic tests. We conducted three meta-analyses of 46 eligible studies with matched pre- and postoperative data to calculate the odds ratio of new vertigo onset, as well as the impairment of vestibular receptors measured by nystagmography and cervical vestibular evoked myogenic potentials (cVEMP). Postoperative vertigo was calculated from 95 studies and further subdivided by mean age with pooled data.

RESULTS

We observed a significant increase in postoperative vertigo and significant impairment of nystagmography and cVEMP detection. Vertigo after cochlear implantation was reported in 9.3% of the patients with a continuous increase in patient age at surgery. In a subgroup of studies, new onset of vertigo was found in 17.4% of the patients. In addition, 7.2% of the patients had persisting vertigo complaints, whereas 11.6% described an altered vertigo quality and 7.7% had their preoperative complaints resolved. A comparison of round window approach and cochleostomy revealed significantly increased vertigo after cochleostomy. Both insertion methods showed similar effects in nystagmography and cVEMP testing.

CONCLUSION

Cochlear implantation has a significant impact on subjective vertigo and vestibular receptor function. This is affected by the patient's age at the time of surgery. The surgical technique (round window or cochleostomy) may influence the outcome, but this requires further investigation. Younger patients may compensate better following vestibular dysfunction. Perioperative testing is required to correlate vestibular impairment and subjective complaints. Laryngoscope, 2018 Laryngoscope, 128:2110-2123, 2018.

Impairment of Caloric Function After Cochlear Implantation

PURPOSE

This article seeks to review current literature on caloric function following cochlear implantation while analyzing any correlations of caloric function changes with vestibular symptoms.

METHOD

This article is a systematic review of evidence-based literature. English language articles published between 1980 and 2014 that presented some form of caloric data from cochlear implant (CI) patients and that did not solely analyze overlapping data from a previous study were reviewed. Twenty-five articles met these criteria.

RESULTS

Of the 439 individuals tested, 37% of patients demonstrated reduced maximum slow-phase velocity, and 34% had onset of caloric asymmetry post-CI.

CONCLUSIONS

This review article found that cochlear implantation can affect caloric responses but is variable. When counseling patients preoperatively, possible effects of CI on labyrinthine function should be discussed.

The advantages of sound localization and speech perception of bilateral electric acoustic stimulation

CONCLUSION

Bilateral electric acoustic stimulation (EAS) effectively improved speech perception in noise and sound localization in patients with high-frequency hearing loss.

OBJECTIVE

To evaluate bilateral EAS efficacy of sound localization detection and speech perception in noise in two cases of high-frequency hearing loss.

METHODS

Two female patients, aged 38 and 45 years, respectively, received bilateral EAS sequentially. Pure-tone audiometry was performed preoperatively and postoperatively to evaluate the hearing preservation in the lower frequencies. Speech perception outcomes in quiet and noise and sound localization were assessed with unilateral and bilateral EAS.

RESULTS

Residual hearing in the lower frequencies was well preserved after insertion of a FLEX(24) electrode (24 mm) using the round window approach. After bilateral EAS, speech perception improved in quiet and even more so in noise. In addition, the sound localization ability of both cases with bilateral EAS improved remarkably.

Vestibular function in children with auditory neuropathy spectrum disorder

OBJECTIVE

Children with auditory neuropathy spectrum disorder (ANSD) account for about 10% of paediatric patients referred for cochlear implantation. Vestibulopathy may be associated with ANSD, and may have implications when formulating management plans in this patient group. We wanted to determine the incidence and predictive factors for vestibulopathy in this patient group to guide vestibular testing in this patient population, and give insight to the aetiology of ANSD.

METHODS

We reviewed the outcomes of vestibular function testing in a cohort of paediatric patients with ANSD.

RESULTS

Probable or definite vestibulopathy was seen in 42% of patients who were tested. Vestibulopathy was associated with medical co-morbidities, but was not associated with imaging findings.

CONCLUSIONS

Vestibulopathy is relatively prevalent in this patient group, and should be considered when planning the investigation and management of children with ANSD.

Hearing preservation and clinical outcome of 32 consecutive electric acoustic stimulation (EAS) surgeries

Conclusions

Our results indicated that electric acoustic stimulation (EAS) is beneficial for Japanese-speaking patients, including those with less residual hearing at lower frequencies. Comparable outcomes for the patients with less residual hearing indicated that current audiological criteria for EAS could be expanded. Successful hearing preservation results, together with the progressive nature of loss of residual hearing in these patients, mean that minimally invasive full insertion of medium/long electrodes in cochlear implantation (CI) surgery is a desirable solution. The minimally invasive concepts that have been obtained through EAS surgery are, in fact, crucial for all CI patients.

Objectives

This study was conducted to evaluate hearing preservation results and speech discrimination outcomes of hearing preservation surgeries using medium/long electrodes.

Methods

A total of 32 consecutive minimally invasive hearing preservation CIs (using a round window approach with deep insertion of a flexible electrode) were performed in 30 Japanese patients (two were bilateral cases), including patients with less residual hearing. Hearing preservation rates as well as speech discrimination/perception scores were investigated on a multicenter basis.

Results

Postoperative evaluation after full insertion of the flexible electrodes (24 mm, 31.5 mm) showed that residual hearing was well preserved in all 32 ears. In all patients, speech discrimination and perception scores were improved postoperatively.