Vestibular Function in Children and Adults Before and After Unilateral or Sequential Bilateral Cochlear Implantation

A Systematic Review and Meta-Analysis of Post-Cochlear Implant Vestibular Dysfunction: Round Window Versus Standard Cochleostomy Approaches

BACKGROUND

Two main techniques for cochlear implantation (CI) are commonly used: the standard cochleostomy (SCA) and the round window approach (RWA). Initially, the RWA was more utilized, followed by the SCA for cases with challenging visualization. Recent studies show that RWA is preferred due to SCA's risk of damaging cochlear structures.

AIM

We aim to compare post-CI complications between the RWA and SCA approaches.

METHODS

Five electronic databases were systematically searched to identify relevant studies. Eligibility screening was performed to determine inclusion criteria, and data extraction from the selected studies was conducted independently. Dichotomous outcomes were pooled as rate ratios (RR) and standard errors (SE), with significance determined by a p value >0.05 between CI subgroups. The generic inverse variance analysis method was applied with the employment of the random-effect model.

RESULTS

Our systematic review encompassed 82 studies, of which 58 were eligible for meta-analysis. Vertigo was documented in 10% of instances utilizing the RWA technique and in 8% of cases using the SCA method. Likewise, dizziness was noted in 18% of RWA cases and in 14% of SCA cases. The overall incidence of vestibular complications was 36% for RWA and 17% for SCA. However, statistical analysis revealed no significant differences between these approaches ( p < 0.05).

CONCLUSION

Both the RWA and the SCA approaches demonstrate comparable post-CI complication profiles concerning dizziness, vertigo, and overall vestibular complications, with the RWA approach showing slightly higher incidences. However, no significant difference was found between the two techniques.

Inner Ear Pathologies After Cochlear Implantation in Guinea Pigs: Functional, Histopathological, and Endoplasmic Reticulum Stress-Mediated Apoptosis

OBJECTIVES

Vestibular dysfunction is one of the most common complications of cochlear implantation (CI); however, the pathological changes and mechanisms underlying inner ear damage post-CI remain poorly understood. This study aimed to investigate the functional and histopathological changes in the cochlea and vestibule as well as endoplasmic reticulum (ER) stress-mediated apoptosis in guinea pigs after CI.

DESIGN

Auditory brainstem response, ice water test, and vestibular evoked myogenic potentials were used to assess cochlear and vestibular function in guinea pigs before and after CI. Histopathological analyses were conducted at various time points post-CI to observe morphological changes in the cochlea and vestibule, as well as the impact of ER stress on these tissues.

RESULTS

After CI, 10.7% (9/84) of the guinea pigs exhibited nystagmus and balance dysfunction. Auditory brainstem response thresholds increased significantly after CI, and air-conducted cervical and ocular vestibular evoked myogenic potential response rates decreased. The ice water test revealed a gradual reduction in nystagmus elicitation rates, along with decreased nystagmus frequency, prolonged latency, and shortened duration. Histopathological analysis of the cochlea revealed fibrous and osseous tissue formation in the scala tympani and a reduction in hair cells and spiral ganglion cells. In the vestibule, alterations included flattening the ampullary crista and disorganized sensory epithelial cells. Transmission electron microscopy revealed pathological changes including cytoplasmic vacuolization and chromatin uniformity in both cochlear and vestibular hair cells. ER stress was prominent in the cochlea, while no substantial stress response was observed in the vestibule.

CONCLUSIONS

Our study highlights the various effects of CI surgery on cochlear and vestibular function and morphology in guinea pigs. ER stress-mediated apoptosis may contribute to secondary cochlear damage, whereas the vestibular system demonstrates adaptive responses that preserve cellular homeostasis. These findings provide insights into potential mechanisms underlying inner ear complications post-CI.

Long-Term Follow-Up of Vestibular Function in Cochlear-Implanted Teenagers and Young Adults

BACKGROUND

Vestibular function implements head position regulation and body spatial navigation. It matures during childhood and adolescence and integrates with the completion of an individual's motor development. Nevertheless, vestibular impairment is associated with profound paediatric hearing loss and has a negative impact on the child's motor proficiency. Cochlear implantation (CI) is the treatment of choice for severe hearing loss, where conservative treatment plans are not appropriate or fail. The Teenager and Young Adults Cochlear Implant (TAYACI) study investigates the long-term outcomes of early implantation with respect to the hearing, speech, psychological, and balance development among CI users.

METHODS

This study focuses on the vestibular function and the appropriate methods for vestibular assessment. The results of two established vestibular test methods are explored: the video head impulse test (vHIT) and cervical/ocular vestibular-evoked myogenic potentials (cVEMP, oVEMP) with air and bone conduction vibration stimulation. The results of vHIT, cVEMP, and oVEMP, per implanted ear and the relation to the aetiology of hearing loss are reported. An additional dynamic visual acuity (DVA) test was included to assess clinical oscillopsia.

RESULTS

Overall abnormal lateral canal testing was detected in 35/76 (46.1%) of the implanted ears. Bone-conducted cVEMP (BC cVEMP) was pathological in 33/76 (43.3%) and BC oVEMP in 42/76 (55.3%). Lateral canal impairment was associated with the background diagnosis of the hearing loss. Oscillopsia was related to bilateral canal impairment (sensitivity 73% specificity 100%).

CONCLUSIONS

Lateral canal testing together with BC VEMPs were the most reproducible modules for vestibular testing The above tests were related to each other and complemented the overall vestibular assessment. DVA is a helpful tool to screen dynamic oscillopsia in patients with bilateral vestibular impairment.

Prevalence and risk factors for underlying vestibular weakness in cochlear implant candidates

OBJECTIVE

To describe the baseline vestibular function in cochlear implant candidates and identify demographic and audiologic risk factors for vestibular dysfunction.

STUDY DESIGN

Retrospective cohort study (2012-2022) of the CI candidate population.

SETTING

Neurotology practice at large academic hospital.

METHODS

All patients evaluated for CI underwent routine preoperative vestibular evaluation, irrespective of symptoms. Preoperative audiologic data was also analyzed.

RESULTS

Of a total of 180 preoperative VNGs obtained, 39.4% demonstrated preoperative vestibular weakness as determined on caloric testing. Of these, 26.8% had evidence of bilateral weakness, 60.5% unilateral weakness ipsilateral to the worse hearing ear and 12.7% contralateral weakness. Demographic variables such as age, gender, BMI and medical comorbidities including diabetes, hypertension, hyperlipidemia were not found to be associated with a higher risk of vestibular weakness. Patients with vestibular weakness had significantly poorer low tone hearing. Hearing loss at 250 Hz was the strongest prognostic factor for risk of vestibular weakness. Using a cutoff of 45dB at 250 Hz as an indicator for obtaining preoperative VNG was found to have a sensitivity of 92.9% and specificity of 37.9% for identifying vestibular weakness.

CONCLUSIONS

Traditional CI candidates have a high prevalence of preoperative vestibular weakness. Audiologic data and specifically severity of hearing loss in the low frequencies may be a useful indicator of vestibular weakness and thus help guide which patients should undergo preoperative VNG. We propose the cutoff point of 45dB at 250 Hz as an indicator of higher risk for vestibular weakness and recommend preoperative VNG testing for this population prior to surgery.

Risk factors for underlying bilateral vestibular weakness in cochlear implant candidates

Introduction

Cochlear implantation (CI) is associated with postoperative vestibular dysfunction in the implanted ear; however, limited data on baseline vestibular function in these patients exists. Bilateral vestibular weakness is associated with detrimental effects on quality of life. As such, it is important to identify patients with a preexisting bilateral weakness and consider this information in surgical planning.

Methods

Retrospective cohort study of the CI candidate population. All patients underwent routine preoperative vestibular evaluation, irrespective of symptoms.

Results

Of 180 preoperative videonystagmographies, 39.4% showed vestibular weakness determined by caloric testing. Of these, 26.8% exhibited bilateral weakness. Patients with bilateral weakness had higher body mass index (31.6 kg/m2) than those with unilateral weakness or normal function (26.2 and 27.4 kg/m2, P = 0.007). Further analysis of the audiologic data in the worse-hearing ear revealed worse hearing at 250, 500, and 1000 Hz (P < 0.05). Hearing threshold of 60 dB or worse at 250 Hz was the best prognostic indicator for bilateral weakness. At a threshold of 60 dB at 250 Hz, all patients with bilateral weakness are captured (100% sensitivity), with a specificity of 34.5%.

Conclusion

More than one-third of CI candidates have some degree of underlying vestibular dysfunction and 10.5% exhibit preexisting bilateral weakness. This study indicates that audiologic data may be a useful prognostic indicator of preexisting bilateral vestibular weakness. Given the well-documented detrimental effects of bilateral vestibular weakness on quality of life, we recommend that all patients who meet this cutoff undergo vestibular testing to assess for an underlying weakness.

Brazilian Society of Otology task force - cochlear implant ‒ recommendations based on strength of evidence

OBJECTIVE

To make evidence-based recommendations for the indications and complications of Cochlear Implant (CI) surgery in adults and children.

METHODS

Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on cochlear implantation were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions.

RESULTS

The topics were divided into 2 parts: (1) Evaluation of candidate patients and indications for CI surgery; (2) CI surgery - techniques and complications.

CONCLUSIONS

CI is a safe device for auditory rehabilitation of patients with severe-to-profound hearing loss. In recent years, indications for unilateral hearing loss and vestibular schwannoma have been expanded, with encouraging results. However, for a successful surgery, commitment of family members and patients in the hearing rehabilitation process is essential.

Effect of Cochlear Implantation on Air Conduction and Bone Conduction Elicited Vestibular Evoked Myogenic Potentials-A Scoping Review

Background/Objectives: Cochlear implantation (CI) is an effective intervention for individuals with severe to profound hearing loss; however, it may impact vestibular function due to its proximity to related anatomical structures. Vestibular evoked myogenic potentials (VEMPs) assess the function of the saccule and utricle, critical components of the vestibular system. This review examines CI's impact on air conduction (AC) and bone conduction (BC) VEMP responses. Methods: A scoping review was conducted following PRISMA guidelines, using databases such as Medline, Embase, Cochrane Library, Scopus, and ProQuest Dissertations. Studies reporting on AC and/or BC-VEMP in CI recipients were included. Data extraction focused on VEMP response rates, amplitudes, and latencies pre- and post-CI. Risk of bias/quality assessment was performed using the Newcastle-Ottawa Scale. Results: Out of 961 studies identified, 4 met the inclusion criteria, encompassing a total of 245 CI-implanted ears. Results indicated that AC-VEMP responses were often reduced or absent post-CI, reflecting the influence of surgical changes in the middle ear mechanics rather than otolith dysfunction. In contrast, BC-VEMP responses were more consistently preserved, suggesting that BC stimuli bypass the middle ear and more accurately delineate otolith function. Variations in VEMP outcomes were noted depending on the surgical approach and individual patient factors. Conclusions: CI impacts vestibular function as measured by VEMP, with AC-VEMP showing greater susceptibility to postoperative changes compared to BC-VEMP. The presence of preserved BC-VEMP alongside absent AC-VEMP underscores the need to differentiate between these measures in assessing vestibular function.

Long term effects of cochlear implant surgery on vestibular system in pediatric population

OBJECTIVE

The aim was to evaluate the vestibular system of children who had undergone cochlear implant surgery and to compare them with the healthy population by vestibulo-ocular reflex (VOR) gains in unilateral and bilateral implant users, with the implants both on and off.

METHODS

Patients older than 5 years who had undergone cochlear implant surgery between 2012 and 2020 and who were cochlear implant users for at least one year were included. After consent was obtained, a video head impulse test (VHIT) was performed to evaluate the three semicircular canals, with devices on and off, and VOR gains were evaluated. VHIT was also used to assess VOR gains in the control group. The VOR gains of the study and control groups, VOR gains of unilateral and bilateral implant users, and VOR gains with implants on and off were compared.

RESULTS

When the VOR gains of 24 unilateral and 13 bilateral cochlear implant users and the control group (n = 30) were compared, a significant difference was found only in the anterior semicircular canal, although the VOR gains were found to be low in all three semicircular canals in the implant users (p < 0.05). There was no significant difference between the VOR gains of unilateral and bilateral implant users. There was no significant difference between the VOR gains when either on or off. There was no correlation between cochlear implant usage time, implant insertion age, patient age and VOR gain.

CONCLUSION

The effects of cochlear implant surgery on the vestibular system continue in the late period, but no correlation was observed between implant usage time and VOR gain after the first year. It was observed that having the cochlear implant on or off had no effect on VOR gain. Furthermore, bilateral implant surgery did not lead to additional vestibular dysfunction compared to unilateral implant surgery.

Vestibulo-ocular reflex dynamics with head-impulses discriminates Usher patients type 1 and 2

Usher Syndrome classification takes into account the absence of vestibular function but its correlation with genotype is not well characterized. We intend to investigate whether video Head Impulse Test (vHIT) is useful in screening and to differentiate Usher Syndrome types. 29 Usher patients (USH) with a genetically confirmed diagnosis and 30 healthy controls were studied with vHIT and dizziness handicap inventory questionnaire (DHI). Statistical significant differences between USH1, USH2 and controls were found in the vestibulo-ocular-reflex (VOR) gain of all SCCs, with USH1 patients consistently presenting smaller gains. VOR gain of the right lateral SCC could discriminate controls from USH1, and USH2 from USH1 with an overall diagnostic accuracy of 90%. USH1 DHI correlated with VOR (ρ = - 0,971, p = 0.001). Occurrence rate of covert and overt lateral semicircular canals refixation saccades (RS) was significantly different between groups, being higher in USH1 patients (p < 0.001). USH1 peak velocity of covert and overt saccades was higher for lateral semicircular canals (p < 0.05 and p = 0.001) compared with USH2 and controls. Covert saccades occurrence rate for horizontal SCCs could discriminate USH1 from USH2 patients and controls with a diagnostic accuracy of 85%. vHIT is a fast and non-invasive instrument which allowed us to screen and distinguish Usher patients from controls with a high precision. Importantly, its use allowed further discrimination between USH1 from USH2 groups. Moreover, VOR gain seems to correlate with vertigo-related quality of life in more severe phenotypes.

Predictive Factors for Subjective Vertigo Following Cochlear Implantation: A Regional Multicenter Cohort Study of 395 Patients

INTRODUCTION

Cochlear implantation (CI) is generally accepted as having a low rate of postoperative complications, but between 9.3% and 13% of cases experience vertigo postoperatively. This study aimed to examine patient, surgical, and device factors contributing toward the risk of postoperative vertigo.

METHODOLOGY

A retrospective review was conducted of adult patients who underwent cochlear implant in a regional area of New South Wales from 2007 to 2018. A total of 395 cochlear implant cases were included in the final study.

RESULTS

The overall incidence of vertigo at 3 months of follow-up was 7.1% (n = 28/395). No difference was identified in this study between rates of postoperative vertigo between device factors, including implant make (Cochlear vs. Med-El), electrode shape (perimodiolar vs. straight), and electrode model. No significant difference was found also for surgical factors such as the number of electrode rings inserted, side of implantation, or surgical approach of tympanic ramp (round window insertion vs. cochleostomy).A higher percentage of patients with preoperative vertigo experienced vertigo postoperatively (18.4%, n = 7/38), compared with the population without preoperative vertigo (6.0%, n = 21/352) ( p = 0.005). Patients with previous mastoid surgery also reported a higher rate of postoperative vertigo (20%, n = 9/45) compared with those who had not had mastoid surgery (5.43%, n = 19/350) ( p = 0.006). The mean age of patients experiencing postoperative vertigo was higher than the population without postoperative symptoms (67 vs. 63).

CONCLUSION

This study of a large multicenter population outlines that patient factors are more critical than surgical or device factors when considering risk factors for vertigo post-cochlear implant.

A longitudinal study of cortical auditory maturation and implications of the short inter-implant delay in children with bilateral sequential cochlear implants

OBJECTIVE

This longitudinal study aimed to investigate the maturational development of P1 latency and the effects of a short inter-implant delay in children who received bilateral sequential cochlear implants.

MATERIALS AND METHODS

Fourteen children (first CI mean age: 1.4 ± 0.4 years and Second CI mean age: 3.3 ± 0.5 years) who had received sequential bilateral cochlear implants during the sensitive period for auditory maturation participated in our study. The speech-evoked cortical P1 response was recorded after the activation of the second CI at four intervals (implant activation, 3 months, 6 months, 12 months) under three listening conditions (first CI, second CI, binaural).

RESULTS

Our results showed that the P1 latencies of the second CI reached normative values within 3 months, but did not reach the P1 latency of the first CI until 12 months. We found a strong negative correlation between the inter-implant delay and the P1 latencies of the second CI when the second CI was activated.

CONCLUSION

Changes in cortical auditory responses over time resulted in normal auditory maturation in children with sequential bilateral cochlear implants during the sensitive period. The results also provide evidence that the timing of auditory experience in the first ear during the sensitive period may influence the speed of compensation in children receiving sequential cochlear implants.

Task force Guideline of Brazilian Society of Otology ‒ hearing loss in children - Part I ‒ Evaluation

OBJECTIVES

To provide an overview of the main evidence-based recommendations for the diagnosis of hearing loss in children and adolescents aged 0 to 18 years.

METHODS

Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on childhood hearing loss were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions.

RESULTS

The evaluation and diagnosis of hearing loss: universal newborn hearing screening, laboratory testing, congenital infections (especially cytomegalovirus), genetic testing and main syndromes, radiologic imaging studies, vestibular assessment of children with hearing loss, auditory neuropathy spectrum disorder, autism spectrum disorder, and noise-induced hearing loss.

CONCLUSIONS

Every child with suspected hearing loss has the right to diagnosis and appropriate treatment if necessary. This task force considers 5 essential rights: (1) Otolaryngologist consultation; (2) Speech assessment and therapy; (3) Diagnostic tests; (4) Treatment; (5) Ophthalmologist consultation.

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.

Minimally invasive surgical techniques in vestibular function preservation in patients with cochlear implants

Background

Cochlear implantation (CI) is an effective and successful method of treating individuals with severe-to-profound sensorineural hearing loss (SNHL). Coupled with it’s great clinical effectiveness, there is a risk of vestibular damage. With recent advances in surgical approach, modified electrode arrays and other surgical techniques, the potential of hearing preservation (HP) has emerged, in order to preserve the inner ear function. These techniques may also lead to less vestibular damage. However, a systematic study on this at different follow-ups after CI surgery has not been documented before.

Aims

To investigate changes of vestibular function systematically in recipients at short and long follow-ups after a minimally invasive CI surgery.

Methods

In this retrospective study, 72 patients (72 ears) with minimally invasive CI were recruited. All participants selected had bilateral SNHL and pre-operative residual hearing (RH) and underwent unilateral CI. They were treated to comprehensive care. All patients underwent vestibular function tests 5 days prior to CI. During the post-operative period, follow-up tests were performed at 1, 3, 6, 9, and 12 months. The contemporaneous results of caloric, cervical vestibular-evoked myogenic potential (cVEMP), ocular vestibular-evoked myogenic potential (oVEMP), and video head impulse (vHIT) tests were followed together longitudinally.

Results

On the implanted side, the percent fail rate of caloric test was significantly higher than that of vHIT at 1, 3, and 9 months post-operatively (p < 0.05); the percent fail rate of oVEMP was higher than vHIT of superior semicircular canal (SSC), posterior semicircular canal (PSC), or horizontal semicircular canal (HSC) at 1, 3, and 9 months (p < 0.05); at 3 and 9 months, the percent fail rate of cVEMP was higher than that of SSC and PSC (p < 0.05). There were no significant differences in the percent fail rates among all tests at 6 and 12 months post-CI (p > 0.05). The percent fail rates showed decreased trends in caloric (p = 0.319) and HSC tested by vHIT (p = 0.328) from 1–3 to 6–12 months post-operatively. There was no significant difference in cVEMP between 1–3 and 6–12 months (p = 0.597). No significant differences on percent fail rates of cVEMP and oVEMP between short- and long-terms post-CI were found in the same subjects (p > 0.05). Before surgery, the abnormal cVEMP and oVEMP response rates were both lower in patients with enlarged vestibular aqueduct (EVA) than patients with a normal cochlea (p = 0.001, 0.018, respectively).

Conclusion

The short- and long-term impacts on the vestibular function from minimally invasive CI surgery was explored. Most of the vestibular functions can be preserved with no damage discrepancy among the otolith and three semicircular canal functions at 12 months post-CI. Interestingly, a similar pattern of changes in vestibular function was found during the early and the later stages of recovery after surgery.

Effect of cochlear implantation on vestibular function in children: A scoping review

Objective

To provide a scoping review of the available literature for determining objectively the effect of cochlear implantation on vestibular function in children.

Methods

A literature search was performed and the following criteria were applied: vestibular tests that were performed on subjects within the range of 0-18 years old before and after cochlear implantation. The papers conducted at least one of the following tests: (video) head impulse test, caloric test, cervical and ocular vestibular evoked myogenic potentials or rotatory chair test. Included papers underwent quality assessment and this was graded by risk of bias and directness of evidence.

Results

Fourteen articles met the selection criteria. The included studies showed that cochlear implantation leads to a decrease in vestibular function in a proportion of the patient population. This loss of vestibular function can be permanent, but (partial) restoration over the course of months to years is possible. The pooling of data determined that the articles varied on multiple factors, such as time of testing pre- and post-operatively, age of implantation, etiologies of hearing loss, used surgical techniques, type of implants and the applied protocols to determine altered responses within vestibular tests. The overall quality of the included literature was deemed as high risk of bias and medium to low level of directness of evidence. Therefore, the data was considered not feasible for systematic analysis.

Conclusion

This review implicates that vestibular function is either unaffected or shows short-term or permanent deterioration after cochlear implantation in children. However, the heterogeneity of the available literature indicates the importance of standardized testing to improve our knowledge of the effect of cochlear implantation on the vestibular function and subsequent developmental consequences for the concerned children.

Vestibular function in children with cochlear implant: Impact and evaluation

Over the last 30 years, cochlear implant (CI) has been dedicated to improving the rehabilitation of hearing impairments. However, CI has shown potential detrimental effects on vestibular function. For children, due to atypical symptoms and difficulty in cooperating with vestibular function tests, systematic and objective assessments of vestibular function with CI have been conducted sparsely. This review focuses on the impact of vestibular function in children with CI and summarized the evaluation of vestibular function in children. In addition, some recommended strategies are summarized and proposed.

The effect of cochlear implant surgery on vestibular function in adults: A meta-analysis study

Issue

The findings in literature indicate inconsistency in the complications caused by the implant of electrodes in the cochlea; vestibular alterations and balance disorders are mentioned as the most likely.

Purpose

To evaluate, in literature, through the results of multiple vestibular function tests, the effects of cochlear implant surgery on postural stability in adult patients and to analyze.

Hypothesis

From the PICO strategy, where the Population focuses on adults, Intervention is cochlear implant surgery, Comparisons are between implanted patients, and Outcomes are the results of the assessment of cochlear function, the research question was formulated: Are there deficits in vestibular function in adults undergoing cochlear implant placement?

Method

Systematic review based on cohort, case–control, and cross-sectional observational studies. Information sources: Databases between 1980 and 2021, namely, PubMed, Cinahl, Web Of Science, Cochrane, and Scopus. Search strategy using Mesh terms: “Adult,” “Cochlear Implant,” “Postural Balance,” “Posturography,” “Cochlear Implant,” “Dizziness,” “Vertigo,” “Vestibular Functional Tests,”and “Caloric Tests.” Populational inclusion criteria: studies with adult patients; intervention: cochlear implant placement surgery; comparison: analysis of a vestibular function with vestibular test results and pre- and postoperative symptoms; outcome: studies with at least one of the vestibular function tests, such as computerized vectoelectronystagmography (VENG), vestibular-evoked myogenic potentials (VEMPs), caloric test, video head impulse test (VHIT), head impulse test (HIT), videonystagmography, (VNG) and static and dynamic posturography. Exclusion criteria: studies without records of pre- and postoperative data collection and studies with populations under 18 years of age. Screening based on the reading of abstracts and titles was performed independently by two reviewers. In the end, with the intermediation of a third reviewer, manuscripts were included. Risk of bias analysis, performed by two other authors, occurred using the JBI “Critical Appraisal Checklist.”

Results

Of the 757 studies, 38 articles met the inclusion criteria. VEMP was the most commonly used test by the studies (44.7%), followed by the caloric test (36.8%) and vHIT (23.6%). Most studies performed more than one test to assess vestibular function.

Conclusion

Among all vestibular tests investigated, the deleterious effects on vestibular function after cochlear implant surgery were detected with statistical significance (P < 0.05) using VEMP and caloric test. Comparing abnormal and normal results after implant surgery, the vestibular apparatus was evaluated as having abnormal results after cochlear implant surgery only in the VEMP test. The other tests analyzed maintained a percentage mostly considered normal results.

Systematic review registration

identifier: CRD42020198872.