Vestibular function in cochlear implantation: Correlating objectiveness and subjectiveness

Postural stability at activation and deactivation of the cochlear implant in adolescents with late lateral implantations: a quasi-experiment

BACKGROUND

Cochlear implantation (CI) surgery has become a prevalent method of hearing rehabilitation, since it has been acknowledged that it impacts effectively on the vestibular system. However, there is still no consensus among clinicians on the most appropriate age and area (lateral/bilateral) of CI surgery in terms of postural control. The present study aimed to assess the postural control in late lateral CI adolescents with different visual (eyes opened(EO)/eyes closed(EC)) and auditory (CI activated/deactivated) conditions and to build a theoretical model of postural control based on sensual compensatory mechanisms that are predominant in late CI individuals. It was hypothesized that kinesthetic sensation and exteroceptors of the superficial sensation are critical for neuromuscular control after late CI.

METHODS

A quasi-experimental study protocol was used in this study to assess the postural stability performance in the studied adolescents with different visual and auditory perceptions. 27 adolescent students with hearing loss participated in the study. A force plate (Accu Gait AMTI) with computer software (NetForce) was used in the study to assess the postural stability with four different conditions(EO)/EC), CI activated/deactivated).

RESULTS

vCOP was found to have a significant growing tendency within the conditions of CI activated/deactivated.No statistically significant relationships were noted between the range of the displacement of feet pressure (Area) and both the visual and auditory conditions. Hearing loss etiology was statistically significantly related to the values of vCOP, within the conditions of EO, CI activated/deactivated (p < 0.01), what did not occure with the condition of EC (p > 0.05). Neuromuscular control with the condition of EC x CI deactivated was found to be based on the kinesthetic-tactual compensatory model.

CONCLUSIONS

Kinesthetic sensation and exteroceptors of the superficial sensation seem to be the predominant source of information to maintain postural control in late CI adolescents, regardless of the visual and auditory conditions. The etiology of hearing loss (congenital/acquired) can be a predictor of the values of the vCOP. In order to improve neuromuscular control in this population, it is recommended that the patients perform physical activity tasks, especially to develop core muscles, based on direct stimulation and rotational stability.

Does Location of Intralabyrinthine Vestibular Schwannoma Determine Objective and Subjective Vestibular Function?

BACKGROUND AND OBJECTIVE

The incidence of intralabyrinthine schwannomas is increasing, and a growing attention is given to the detrimental effects on hearing function. On the contrary, the vestibular profile of intralabyrinthine vestibular schwannomas (VSs) is still not well understood. We aimed to investigate and report the observed relationships between the intralabyrinthine location of the schwannomas and objective and subjective vestibular profile of the patients.

METHODS

Retrospective cohort study of 20 consecutive individuals with sporadic intralabyrinthine schwannomas and grouped according to the intralabyrinthine location of the schwannomas. Vestibular testing consisted of the video head impulse test of all three semicircular canals, the caloric test, cervical and ocular vestibular evoked myogenic potentials, and the dizziness handicap inventory. A nonparametric unpaired t test was performed to compare groups, and Fisher's exact test was used for categorical data.

RESULTS

The median video head impulse test gains (lateral, anterior, posterior) were 0.40, 0.50, and 0.75 for intravestibular schwannomas and 0.93, 1.52, and 0.91 for intracochlear schwannomas ( p = 0.0001, p = 0.009, p = 0.33), respectively. Caloric unilateral weakness had a median of 100% for intravestibular schwannomas and 14% for intracochlear schwannomas ( p = 0.0001). The mean dizziness handicap inventory was 21 for intravestibular schwannomas and 1 for cochlear schwannomas ( p = 0.02). There were no significant differences in vestibular evoked myogenic potentials according to intralabyrinthine location.

CONCLUSION

By both objective and subjective measures, intralabyrinthine schwannomas with an intravestibular component has significantly worse vestibular function than schwannomas with purely cochlear involvement.

Balancing Act: A Comprehensive Review of Vestibular Evaluation in Cochlear Implants

Cochlear implantation, a transformative intervention for individuals with profound hearing loss, has evolved significantly over the years. However, its impact on the vestibular system, responsible for balance and spatial orientation, remains a subject of ongoing research and clinical consideration. This narrative review highlights key aspects of vestibular evaluation in patients undergoing cochlear implantation. Preoperative vestibular assessment is crucial to establish baseline vestibular function and identify any pre-existing balance issues. Various tests, including caloric, rotational chair, vestibular-evoked myogenic potential, and video head impulse tests, play a vital role in evaluating vestibular function. The goal is to assess the risk of vestibular disturbances arising from the surgery, guide surgical planning, and detect pre-existing alterations that could be totally or partially compensated. While some patients experience minimal vestibular disruptions, others may encounter transient or persistent balance issues following cochlear implant surgery. Postoperative vestibular testing allows for the early detection of such disturbances, enabling timely interventions like vestibular rehabilitation and evaluating changes produced due to surgical complications or changes in the patient's prior conditions. Challenges in vestibular evaluation include individual variability in patient responses, the proximity of the cochlea to the vestibular system, and the need to tailor testing protocols to individual needs. Further research is essential to refine testing protocols, minimize vestibular disturbances, and improve outcomes for cochlear implant candidates. A multidisciplinary approach involving otolaryngologists, audiologists, and physical therapists is integral to comprehensive patient care in this context. In conclusion, vestibular evaluation in patients undergoing cochlear implantation is critical for optimizing surgical planning, managing postoperative issues, and enhancing the overall quality of life for individuals embarking on the journey of restored hearing.

Post Cochlear Implantation Vertigo: Ictal Nystagmus and Audiovestibular Test Characteristics

OBJECTIVE

To investigate ictal nystagmus and audiovestibular characteristics in episodic spontaneous vertigo after cochlear implantation (CI).

STUDY DESIGN

Retrospective and prospective case series.

PATIENTS

Twenty-one CI patients with episodic spontaneous vertigo after implantation were recruited.

INTERVENTIONS

Patient-initiated home video-oculography recordings were performed during one or more attacks of vertigo, using miniature portable home video-glasses. To assess canal and otolith function, video head-impulse tests (vHITs) and vestibular-evoked myogenic potential tests were conducted.

MAIN OUTCOME MEASURES

Nystagmus slow-phase velocities (SPVs), the presence of horizontal direction-changing nystagmus, and post-CI audiovestibular tests.

RESULTS

Main final diagnoses were post-CI secondary endolymphatic hydrops (48%) and exacerbation of existing Ménière's disease (29%). Symptomatic patients demonstrated high-velocity horizontal ictal-nystagmus (SPV, 44.2°/s and 68.2°/s in post-CI secondary endolymphatic hydrop and Ménière's disease). Direction-changing nystagmus was observed in 80 and 75%. Two were diagnosed with presumed autoimmune inner ear disease (SPV, 6.6°/s and 172.9°/s). One patient was diagnosed with probable vestibular migraine (15.1°/s).VHIT gains were 0.80 ± 0.20 (lateral), 0.70 ± 0.17 (anterior), and 0.62 ± 0.27 (posterior) in the implanted ear, with abnormal values in 33, 35, and 35% of each canal. Bone-conducted cervical and ocular vestibular-evoked myogenic potentials were asymmetric in 52 and 29% of patients (all lateralized to the implanted ear) with mean asymmetry ratios of 51.2 and 35.7%. Reversible reduction in vHIT gain was recorded in three acutely symptomatic patients.

CONCLUSION

High-velocity, direction-changing nystagmus time-locked with vertigo attacks may be observed in post-CI implant vertigo and may indicate endolymphatic hydrops. Fluctuating vHIT gain may be an additional marker of a recurrent peripheral vestibulopathy.

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.

Control of Disabling Vertigo in Ménière's Disease Following Cochlear Implantation without Labyrinthectomy

BACKGROUND

The placement of a cochlear implant (CI) can restore auditory function in the case of profound cochlear deafness, which may be due to Ménière's disease (MD) or be associated with symptoms related to endolymphatic hydrops. The usual treatment of disabling vertigo in MD is based on vestibular deafferentation by labyrinth ablation. The aim of the present study was to retrospectively evaluate the efficacy of the CI in the control of disabling vestibular manifestations in the case of MD unresponsive to medical treatments.

METHODS

A case series of five MD patients with disabling vestibular manifestations associated with profound hearing loss was included. A complete audio-vestibular evaluation was performed after CI positioning.

RESULTS

All patients reported clinical benefits after implant positioning: no vestibular crisis was reported after the surgery. The vHIT and the caloric test showed a normal function or a mild vestibular hypofunction. The auditory performances were comparable to those in the general implanted population. All patients reported subjective tinnitus reduction.

CONCLUSIONS

To date, very few studies have reported vestibular outcomes in hydropic pathology on the implanted side; our results are encouraging. We can therefore confirm the efficacy and safety of the CI as a unique treatment for hearing loss, dizziness, and tinnitus in case of disabling cochlear hydrops, especially in those patients where the history of the disease requires preservation of the vestibular function.

[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.

Objective vestibular function changes in children following cochlear implantation

BACKGROUND:

To date, systematically objective evaluations of vestibular function in children with cochlear implantation (CI) have been conducted sparsely, especially in children with large vestibular aqueduct syndrome (LVAS).

OBJECTIVE:

Our goal was to investigate the function of all five vestibular end-organs pre- and post-cochlear implantation in children with LVAS and normal CT.

METHODS:

In this retrospective cohort study, 34 children (age 4–17 years) with bilateral profound sensorineural hearing loss (SNHL) undergoing unilateral CI were included. Participants included 18 (52.9%) children with LVAS. Objective modalities to evaluate vestibular function included the caloric test, cervical vestibular-evoked myogenic potentials (cVEMP), ocular vestibular-evoked myogenic potentials (oVEMP), and video head impulse test (vHIT). All measurements were performed before surgery and 9 months after surgery.

RESULTS:

Mean age at CI was 8.1±3.7 years. Caloric testing showed hypofunction in 38.2% of cases before implantation and in 50% after (p > 0.05). We found a significant increase of overall abnormality rate in cVEMP and oVEMP from pre- to post-CI (p < 0.05). In all three semicircular canals tested by vHIT, there were no statistically significant mean gain changes (p > 0.05). Higher deterioration rates in cVEMP (53.3%) and oVEMP (52.0%) after surgery were observed (p < 0.05). In children with LVAS, cVEMP revealed a higher deterioration rate than superior semicircular canal (SSC) and posterior semicircular canal (PSC) (p < 0.05). In children with normal CT, the deterioration rates in VEMPs were both higher than those in vHIT (p < 0.05).

CONCLUSIONS:

In general, the otolith organs were the most affected peripheral vestibular sensors in children after cochlear implantation. The variations in otolith function influenced by CI were different between children with LVAS and normal CT. We recommend the use of this vestibular function test battery for children with cochlear implantation.

Long-Term Vestibular Outcomes in Cochlear Implant Recipients

Background: Vestibular dysfunction is likely the most common complication to cochlear implantation (CI) and may, in rare cases, result in persistent severe vertigo. Literature on long-term vestibular outcomes is scarce. Objective: This paper aims to evaluate vestibular dysfunction before and after cochlear implantation, the long-term vestibular outcomes, and follows up on previous findings of 35 consecutive adult cochlear implantations evaluated by a battery of vestibular tests. Methods: A prospective observational longitudinal cohort study was conducted on 35 CI recipients implanted between 2018 and 2019; last follow-up was conducted in 2021. At the CI work-up (T0) and two postoperative follow-ups (T1 and T2), 4 and 14 months following implantation, respectively, all patients had their vestibular function evaluated. Evaluation with a vestibular test battery, involving video head impulse test (vHIT), cervical vestibular evoked myogenic potentials (cVEMP), caloric irrigation test, and dizziness handicap inventory (DHI), were performed at all evaluations. Results: vHIT testing showed that 3 of 35 ears had abnormal vHIT gain preoperatively, which increased insignificantly to 4 of 35 at the last follow-up (p = 0.651). The mean gain in implanted ears decreased insignificantly from 0.93 to 0.89 (p = 0.164) from T0 to T2. Preoperatively, 3 CI ears had correction saccades, which increased to 11 at T2 (p = 0.017). Mean unilateral weakness increased from 19 to 40% from T0 to T2 (p < 0.005), and the total number of patients with either hypofunctioning or areflexic semicircular canals increased significantly from 7 to 17 (p < 0.005). Twenty-nine percent of CI ears showed cVEMP responses at T0, which decreased to 14% (p = 0.148) at T2. DHI total mean scores increased slightly from 10.9 to 12.8 from T0 to T1 and remained at 13.0 at T2 (p = 0.368). DHI scores worsened in 6 of 27 patients and improved in 4 of 27 subjects from T0 to T2. Conclusion: This study reports significant deterioration in vestibular function 14 months after cochlear implantation, in a wide range of vestibular tests. vHIT, caloric irrigation, and cVEMP all measured an overall worsening of vestibular function at short-term postoperative follow-up. No significant deterioration or improvement was measured at the last postoperative follow-up; thus, vestibular outcomes reached a plateau. Despite vestibular dysfunction, most of the patients report less or unchanged vestibular symptoms.

Saccades Matter: Reduced Need for Caloric Testing of Cochlear Implant Candidates by Joint Analysis of v-HIT Gain and Corrective Saccades

Objectives: Video head impulse test (v-HIT) is a quick, non-invasive and relatively cheap test to evaluate vestibular function compared to the caloric test. The latter is, however, needed to decide on the optimal side to perform cochlear implantation to avoid the risk on inducing a bilateral vestibular areflexia. This study evaluates the effectiveness of using the v-HIT to select cochlear implant (CI) candidates who require subsequent caloric testing before implantation, in that way reducing costs and patient burden at the same time.

Study Design: Retrospective study using clinical data from 83 adult CI-candidates, between 2015 and 2020 at the Leiden University Medical Center.

Materials and Methods: We used the v-HIT mean gain, MinGain_LR, the gain asymmetry (GA) and a newly defined parameter, MGS (Minimal Gain & Saccades) as different models to detect the group of patients that would need the caloric test to decide on the ear of implantation. The continuous model MGS was defined as the MinGain_LR, except for the cases with normal gain (both sides ≥0.8) where no corrective saccades were present. In the latter case MGS was defined to be 1.0 (the ideal gain value).

Results: The receiver operating characteristics curve showed a very good diagnostic accuracy with and area under the curve (AUC) of 0.81 for the model MGS. The v-HIT mean gain, the minimal gain and GA had a lower diagnostic capacity with an AUC of 0.70, 0.72, and 0.73, respectively. Using MGS, caloric testing could be avoided in 38 cases (a reduction of 46%), with a test sensitivity of 0.9 (i.e., missing 3 of 28 cases).

Conclusions: The newly developed model MGS balances the sensitivity and specificity of the v-HIT better than the more commonly evaluated parameters such as mean gain, MinGain_LR and GA. Therefore, taking the presence of corrective saccades into account in the evaluation of the v-HIT gain can considerably reduce the proportion of CI-candidates requiring additional caloric testing.

Saccular function evolution related to cochlear implantation in hearing impaired children

Vestibular sensorial input is essential for psychomotor development of the very small children. In consequence, possible vestibular impairment induced by cochlear implantation in deaf children could affect the balance and walking learning process. Some of cochlear implanted children can present congenital vestibular deficit. The anatomical and embryological relation between auditory and vestibular system explains why congenital neurosensorial hearing loss may associate vestibular impairment. The cochlear implant surgery presents a vestibular lesion risk. Bilateral vestibulopathy, as it appears in early childhood, has a poor prognosis for the psychomotor and cognitive development. Even probably rare, bilateral vestibulopathy induced by simultaneous bilateral cochlear implantation can delay the acquisition of motor skills. This pathology can be avoided by an appropriate surgical indication related to the vestibular preoperative status. This study reports the vestibular saccular functional modifications after the cochlear implantation in children. The cervical vestibular evoked myogenic potentials (cVEMPs) were performed in children before and after the cochlear implantation. Since previous studies report different vestibular impairment related to the portelectrode insertion approach, another objective of our study was to assess the saccular postoperative status depending of the insertion by cochleostomy (CO) or through the round window (RW). We performed cVEMPs for 80 patients (135 cochlear implanted ears) before and after cochlear implantation. We have detected preoperative saccular areflexia in 33 (24.4%) ears. In the group of 102 (75.6%) ears with preoperative normal saccular function, 72 (70.6%) ears preserved the cVEMP response after the surgery, while in 30 (29.4%) ears the cVEMP response was lost. Reporting our findings to the portelectrode insertion method, we found normal saccular function in 73.3% of the cochlear implanted ears by RW surgical approach and in 68.42% ears by CO approach. These results suggest that the RW portelectrode insertion is the recommended strategy in order to avoid the saccular vestibular impairment.

Postural Control in Subjects with Incomplete Partition Inner Ear Malformations: A Comparison of Incomplete Partition Types

INTRODUCTION

Children with inner ear malformation (IEM) are at risk of vestibular loss as well as hearing loss. Incomplete partition (IP) anomalies constitute about 41% of all IEMs. This study aimed to investigate the postural control in subjects with the same type of IP on both sides and to compare their results with cochlear implant (CI) users without IEM and healthy peers.

METHODS

The study group consists of 17 subjects with the same IP types on both sides and using auditory implants on at least one side, with the following 3 groups: 6 IP-I subjects (mean age 12.28 ± 6.25), 6 IP-II subjects (mean age 12.90 ± 3.23), and 5 IP-III subjects (mean age 6.98 ± 3.10). Six unilateral CI users (mean age 11.38 ± 3.57) with normal inner ear structures were included in the CI control group, and 6 healthy peers (10.20 ± 4.79) were included in the healthy control group. The postural control was measured using the Bruininks-Oseretsky Test of Motor Proficiency Second Edition (BOT-2) balance subtest. All devices were turned off during the balance test.

RESULTS

The BOT-2 balance scale scores were observed to be significantly different between the IP-I and healthy control group (medians of balance scores being 3.00 and 16.00, respectively, p < 0.001) and the IP-III and healthy control group (medians of balance scores being 6.60 and 16.00, respectively, p = 0.04). The IP-II group had better balance scores (median = 8.00) than those of the other IP groups, although there were no significant differences between the IP-II and other groups (p > 0.05).

CONCLUSION

This study demonstrated that subjects with the same IP type on both sides and with early implantation may differ in terms of their postural control abilities depending on their IP type. Subjects with IP should be regularly followed up by the vestibular assessment and supported by their postural control ability by vestibular rehabilitation.

Vestibular Screening Before Cochlear Implantation: Clinical Implications and Challenges in 409 Cochlear Implant Recipients

OBJECTIVE

Cochlear implantation (CI) carries a risk of loss of vestibular function following surgery. Thus, vestibular assessment presurgery is used to identify vestibulopathy that may contraindicate implantation and guide in selecting the candidate ear. The aim of this study was to evaluate the clinical implications of preoperative vestibular assessment, and to identify challenges in performing vestibular testing in patients with profound hearing loss, i.e., CI candidates.

STUDY DESIGN

Retrospective study of all CI recipients implanted since the introduction of a vestibular screening program.

SETTING

Tertiary referral center in 2013.

PATIENTS AND INTERVENTION

CI candidates routinely underwent testing with the video head impulse test (VHIT) and the cervical vestibular evoked myogenic potential (cVEMP) test as a part of the CI work up.

RESULTS

Three hundred thirty-five individuals were screened before the first CI and 74 individuals before the second CI. In 301 cases (73.6%), the vestibular function was considered normal and consequently carried no contraindications for surgery or implications for choice of ear to be implanted. Bilateral vestibular loss was found in 43 cases (10.5%) and unilateral vestibular loss was found in 62 cases (15.2%). In the latter cases, evaluation of multiple variables was indicated to select candidate ear. In nine implanted patients (2.2%), a relative contraindication to operate based on an "only balancing" ear was overruled by other factors. Vestibular testing was challenged by various factors (e.g., neck immobility, eye tracking issues, communication, and other patient issues), limiting the vestibular data output. This resulted in omittance, testing failure, or interpretation uncertainty 24 times (5.9%) for VHIT and 65 times (15.9%) for cVEMP.

CONCLUSION

Vestibular screening is an important part of the clinical workup with respect to selection of candidate ear for cochlear implantation, as 15.2% of CI candidates present with unilateral vestibulopathy. Challenges in performing the vestibular tests are not uncommon, as test failure occurred in 15.9% of cases for the cVEMP and 5.9% for the VHIT. The most common reasons for test failure were neck immobility, communication issues, and problems of pupil tracking.

Influence of Cochlear Implantation on Vestibular Function in Children With an Enlarged Vestibular Aqueduct

Background: Cochlear implantation (CI) is becoming increasingly used in the rehabilitation of hearing-impaired patients. Children with an enlarged vestibular aqueduct (EVA) need CI for severe or profound hearing loss, with excellent outcomes in hearing rehabilitation. However, vestibular function influenced by CI in children with EVA has not been clarified. We compared the characteristics of vestibular function in implanted children with EVA and those with a normal cochlea.

Methods: In this retrospective case-control study, 16 children with large vestibular aqueduct syndrome (LVAS) and 16 children with a normal cochlea were recruited as the Study and Control Group, respectively. All children (mean age, 10.3 ± 4.4 years) had bilateral profound sensorineural hearing loss (SNHL) and normal pre-operative vestibular functions and underwent unilateral CI. Otolith and canal functions were assessed before CI and 12 months thereafter. Cervical vestibular-evoked myogenic potential (cVEMP), ocular vestibular-evoked myogenic potential (oVEMP), and video head impulse test (vHIT) were evaluated.

Results: Full insertion of the electrode array was achieved in all the cases. Preoperatively, no significant differences in parameters in cVEMP between the Study and Control Group were revealed (p > 0.05). In pre-operative oVEMP, shorter N1 latencies (p = 0.012), shorter P1 latencies (p = 0.01), and higher amplitudes (p = 0.001) were found in the Study than in the Control Group. The Study Group had shorter P1 latency in cVEMP (p = 0.033), and had lower amplitude in oVEMP after implantation (p = 0.03). Statistically significant differences were not found in VOR gains of all three semicircular canals before and after surgery (p > 0.05). VEMP results revealed that the Control Group had significantly lower deterioration rates after CI (p < 0.05). The surgical approach and electrode array had no statistically significant influence on the VEMP results (p > 0.05).

Conclusion: oVEMP parameters differed between children with EVA and children with a normal cochlea before surgery. Systematic evaluations before and after CI showed that otolith function was affected, but all three semicircular canals functions were essentially undamaged after implantation. In contrast to subjects with a normal cochlea, children with EVA are more likely to preserve their saccular and utricular functions after CI surgery. Possible mechanisms include less pressure-related damage, a reduced effect in terms of the air-bone gap (ABG), or more sensitivity to acoustic stimulation.

Vestibular Organ and Cochlear Implantation-A Synchrotron and Micro-CT Study

Background: Reports vary on the incidence of vestibular dysfunction and dizziness in patients following cochlear implantation (CI). Disequilibrium may be caused by surgery at the cochlear base, leading to functional disturbances of the vestibular receptors and endolymphatic duct system (EDS) which are located nearby. Here, we analyzed the three-dimensional (3D) anatomy of this region, aiming to optimize surgical approaches to limit damage to the vestibular organ. Material and Methods: A total of 22 fresh-frozen human temporal bones underwent synchrotron radiation phase-contrast imaging (SR-PCI). One temporal bone underwent micro-computed tomography (micro-CT) after fixation and staining with Lugol's iodine solution (I2KI) to increase tissue contrast. We used volume-rendering software to create 3D reconstructions and tissue segmentation that allowed precise assessment of anatomical relationships and topography. Macerated human ears belonging to the Uppsala collection were also used. Drilling and insertion of CI electrodes was performed with metric analyses of different trajectories. Results and Conclusions: SR-PCI and micro-CT imaging demonstrated the complex 3D anatomy of the basal region of the human cochlea, vestibular apparatus, and EDS. Drilling of a cochleostomy may disturb vestibular organ function by injuring the endolymphatic space and disrupting fluid barriers. The saccule is at particular risk due to its proximity to the surgical area and may explain immediate and long-term post-operative vertigo. Round window insertion may be less traumatic to the inner ear, however it may affect the vestibular receptors.

Objective Vestibular Test Battery and Patient Reported Outcomes in Cochlear Implant Recipients

OBJECTIVE

Cochlear implantation (CI) may have undesired effects on the vestibular apparatus. However, the literature holds no consensus on vestibular affection and the testing tools applied to test for vestibular dysfunction after cochlear implantation are inconsistent. We aimed to investigate the impact of CI on vestibular function by an extensive test battery including patient-reported outcomes.

STUDY DESIGN

Prospective observational study.

SETTING

University hospital.

PATIENTS

Forty adult unilateral first-time CI recipients.

INTERVENTION

Vestibular function was evaluated pre- and post-implantation with the video head impulse test (VHIT), the caloric test and cervical vestibular evoked myogenic potentials (cVEMPs), and the patient-reported dizziness handicap inventory (DHI).

RESULTS

Mean VHIT gain decreased from preoperative 0.92 to 0.84 postoperative (p = 0.018); mean caloric unilateral weakness increased from 20.5% preoperative to 42.9% postoperative (p < 0.0001); cVEMP responses were present on 10 operated ears preoperative and five ears postoperative, and compared with non-implanted ears, cVEMP responses on implanted ears were impaired (p = 0.023). 50% of patients reported early postoperative dizziness, but the mean DHI score remained unchanged (p = 0.94). The DHI scores correlated poorly with the objective outcomes (rs = 0.19 and rs = -0.22).

CONCLUSION

Vestibular function is significantly affected after cochlear implantation, but vestibular hypofunction varies with the test used. Although early dizziness after implantation is common, later DHI scores are not significantly higher than before the implantation, indicating that central compensation plays a major role for these patients.

Video head impulse test saccades and loss of cervical vestibular evoked myogenic potentials are late vestibular footprints of cochlear implantation

BACKGROUND

Cochlear implantation may be complicated by concurrent injury to the vestibular apparatus, potentially resulting in disabling vertigo and balance problems. Information on vestibular function before implantation as measured by the video head impulse test (VHIT) and cervical vestibular evoked myogenic potentials (cVEMPs) is scarce and literature on long-term effects is non-existing.

OBJECTIVE

We aimed to evaluate how vestibular function was affected by cochlear implantation (CI), as measured by VHIT and cVEMPs in the late phase after implantation.

METHODS

Retrospective repeated measurement study.

PATIENTS

Among the 436 patients elected for CI surgery during 2013 to 2018, 45 patients met the inclusion criteria (CI recipients with a vestibular assessment prior to the first CI and a repeated vestibular assessment after the CI operation).

INTERVENTION

VHIT and cVEMPs before and after cochlear implantation. Main outcome measures were vestibular function as evaluated by VHIT gain, saccades and cVEMPs.

RESULTS

The mean time between first and second vestibular screening was 19 months. The mean VHIT gain on implanted ears was 0.79 before the operation and showed no change at follow-up (p = 0.65). Likewise, the number of abnormal VHIT gain values was equal before and after the operation (p = 0.31). Preoperatively, saccades were present on 12 ears (14%) compared with 25 ears (29%) postoperatively (p = 0.013) and were associated with significantly lower VHIT gain values. Preoperatively, positive cVEMPs were found in 20 CI ears (49%) and 24 contralateral ears (62%). 10 CI ears lost cVEMP postoperatively compared with 2 ears on the contralateral side (p = 0.0047).

CONCLUSIONS

Even though VHIT gain has been reported to be affected in the immediate post-implantation period, the findings in this study show that VHIT gain is normalized in the long-term. However, cochlear implantation is associated with the occurrence of VHIT saccades in the long-term and these are associated with lower VHIT gain values. In addition, cVEMP responses are significantly reduced long-term on implanted ears, which agrees with other studies with shorter follow-up.

The effects of age at cochlear implantation on balance in children: A pilot study

AIM

The evaluation of the effects of age at cochlear implantation on balance in children.

RESEARCH DESIGN

Cross-sectional study.

STUDY SAMPLE

Twenty children who received their cochlear implants (CI) before the chronologic age of 48 months (Early CI Group), and 20 children who received their CI at 48 months chronologic age or later (Late CI Group).

INTERVENTION

All children underwent Tandem Romberg (TR) test, Single-Leg stance (SLS) test, Pediatric Clinical Test of Sensory Interaction for Balance (P-CTSIB), Pediatric Balance scale (PBS) and Timed Up and Go (TUG) test.

DATA COLLECTION AND ANALYSIS

The scores of TR, SLS and P-CTSIB and TUG tests and PBS were recorded. Mann Whitney U test and Independent-samples t-test were used to compare data between groups.

RESULTS

TR (eyes opened-EO), SLS (EO), PBS, and TUG scores and incidence in dizziness symptoms did not show significant differences between the groups (p > 0.05). Duration of TR and SLS tests (eyes closed-EC), P-CTSIB-positions 5, and 6 were significantly longer in the Early CI Group than the Late implanted group(p < 0.05).

CONCLUSION

Although the age of cochlear implantation did not affect functional balance for children, it has been found to cause impaired balance performance in difficult static conditions and increased frequency of dizziness.

Prevalence of and Associations With Distress and Professional Burnout Among Otolaryngologists: Part II, Attending Physicians

OBJECTIVE

To ascertain the prevalence of and associations with distress and professional burnout among academic otolaryngology attending physicians.

STUDY DESIGN

Cross-sectional survey.

SETTING

Twelve US academic otolaryngology programs.

METHODS

A questionnaire was administered that encompassed sociodemographic and professional features, the Expanded Physician Well-being Index for distress, the 2-item Maslach Burnout Inventory for professional burnout, the Patient Health Questionnaire-2 screen for major depressive disorder, and the Generalized Anxiety Disorder-2 screen for generalized anxiety disorder.

RESULTS

The survey response rate was 56% and included 186 attending physicians. The average respondent age was 47 years; 72% were men; 93% were married or partnered; and 86% had children. Distress was present in 40%, professional burnout in 26%, positive depression screening in 8%, and positive anxiety screening in 11%. In a univariable setting, age, hours worked in a typical week, nights on call in a typical week, and years of practice were significantly associated with distress, although in a multivariable setting, only hours worked in a typical week remained significantly associated with a positive Expanded Physician Well-being Index screen (odds ratio for each 10-hour increase, 2.61; 95% CI, 1.73-3.93; P < .001). In a univariable setting, hours worked in a typical week was significantly associated with a positive Maslach Burnout Inventory screen.

CONCLUSION

Distress or professional burnout occurs in more than a quarter of academic otolaryngology attending physicians, whereas the prevalence of depression or anxiety is approximately 10%. The number of hours worked per week had the strongest association with distress and burnout. These findings may be used to develop and implement programs to promote physician well-being and mitigate professional burnout.

Functional Loss After Meningitis-Evaluation of Vestibular Function in Patients With Postmeningitic Hearing Loss

Introduction: The inner ear vestibular system is essential to balance function. Although hearing loss is well-described and quite common following meningitis, the literature evaluating vestibular function following meningitis is very limited. In particular, information on results of contemporary vestibular function tests, e.g., the video head impulse test (VHIT), is scarce. Using contemporary vestibular function tests, this study examines the vestibular function of patients with profound hearing loss (HL) after meningitis. Methods: Review of the literature and retrospective controlled study. Patients: Twenty-one consecutive patients with profound HL after meningitis (cochlear implant candidates) matched with 20 patients with profound HL of unknown etiology and examined during the period 2013-2018. Outcome Measure: Vestibular function loss, as evaluated with VHIT vestibulo-ocular reflex (VOR) gain, eye movement saccades, and cervical vestibular-evoked myogenic potentials (cVEMPs). The results of these tests were correlated to inner ear imaging findings (MRI/CT) and the level of hearing loss. Results: Mean VHIT gain was 0.48 in the meningitis group compared to 0.86 in the control group (p < 0.01). Saccades were present in 21 ears (62%) in the meningitis group compared to six ears (15%) among the controls (p < 0.01). cVEMP responses were present on five ears (18%) in the meningitis group and 25 ears (66%) in the control group (p < 0.01). Discussion: Postmeningitic hearing loss is associated with poor vestibular function, as evaluated by VHIT, saccades, and cVEMP. Loss of vestibular function correlates with the degree of hearing loss and inner ear imaging findings, although not in all cases. Vestibular function should be examined in patients surviving meningitis with hearing loss in order to individualize rehabilitation and improve balance outcome.

An exploration of vestibular function pre and post unilateral cochlear implantation

Objectives: To examine the effects of unilateral cochlear implantation on the balance system for adult patients with bilateral severe to profound sensory neural hearing loss. Methods: 7 CI candidates. The function of the sacculus, utricle, and three semi-circular canals (SCCs) was assessed separately using air conduction cervical vestibular evoked myogenic potentials (VEMP), vibration ocular VEMP and the video head impulse test (vHIT) respectively on each side, pre- and post-operatively. Results: The Otoliths appear more affected by implantation than SCCs. In 3 of 7 cases VEMP was affected by implantation. In 2 cases this was associated with short-term dizziness. Discussion: Differential assessment of vestibular end organ function may elucidate how cochlear implantation affects the vestibular system. As many CI candidates have some vestibular function, pre-implant vestibular assessment may help to inform which side of implantation may best preserve that function if other audiology and surgical considerations are equal. Post-implant assessment with VEMP may help to predict short-term dizziness. More work with a larger sample will be needed to make the case for routine clinical assessment. Conclusions: There is potential benefit of conducting multimodal vestibularassessment pre and post cochlear implantation. The otoliths appear more affected by implantation than the SCC.

Vestibular function after cochlear implantation: A test battery and case-by-case approach

OBJECTIVES

The purpose of this study was to assess the effects of cochlear implantation on the functional integrity of the horizontal semicircular canal using multiple methodologies, and to discuss and highlight the limitations of using isolated vestibular tests to assess vestibular function in surgical ears.

METHODS

Ten cochlear implant patients were consented to undergo a preoperative and 3-month postoperative vestibular assessment. The horizontal semicircular canal (SCC) was assessed using three different vestibular test measures that assess function using different stimuli and at different frequencies ranges: caloric testing, sinusoidal harmonic acceleration testing in the rotary chair, and video head impulse testing in the plane of the horizontal SCC. Data was analyzed using different methods: descriptive, statistical, and by an examination of individual case studies.

RESULTS

Each analysis method yielded a different interpretation. Statistical analysis showed no significant group mean differences between baseline pre-op vestibular test results and 3-month post-op vestibular test results. Descriptive analysis showed 30% of individuals presented with postoperative abnormal vestibular testing findings. A case study examination showed that only one patient presented with a post-op decrease in vestibular function in the implanted ear.

CONCLUSIONS

There are several limitations of conventional vestibular testing in postsurgical cochlear implant patients. A test-battery approach, including case history, and test interpretation made on a case-by-case basis is needed to determine whether the patient has undergone vestibular damage, is at risk for falling, or in need of further management.

LEVEL OF EVIDENCE

2b individual cohort study.

Importance of Vestibulo-ocular Reflex Gain and Refixation Saccade Analysis in Individuals with Auditory Neuropathy Spectrum Disorder

Introduction  Auditory neuropathy spectrum disorder (ANSD) features the presence of otoacoustic emissions, poor speech identification score and absent auditory brainstem response. Objective  The present study was designed to evaluate the functioning of all six semicircular canals in individuals with ANSD and to compare it with those of normal-hearing individuals. Methods  A total of 50 individuals participated in the present study, in which Group I comprised 25 normal-hearing individuals, and Group II comprised 25 individuals with ANSD. All of the participants underwent case history, pure tone audiometry, immittance, otoacoustic emissions, auditory evoked response and video head impulse test (vHIT). Results  The independent sample t-test revealed significantly lower vestibulo-ocular reflex gain values in individuals with ANSD. A presence of 100% corrective refixation saccades was observed in the same group. The Pearson correlation test revealed no significant correlation between vestibulo-ocular reflex (VOR) gain with duration of hearing loss and pure tone thresholds for any of the three orthogonal planes. The chi-squared test revealed no association between the VOR gain values and the presence or absence of saccades in any of the semicircular canals ( p  > 0.05). Conclusion  Huge percentages of individuals with ANSD have been found to have associated vestibular dysfunction as well. Therefore, the vHIT can be used as one of the important tests of the vestibular test battery to evaluate all six semicircular canals in individuals with ANSD.

Lateral Semicircular Canal Pressures During Cochlear Implant Electrode Insertion: a Possible Mechanism for Postoperative Vestibular Loss

HYPOTHESIS

Insertion of cochlear implant electrodes generates transient pressure spikes within the vestibular labyrinth equivalent to high-intensity acoustic stimuli.

BACKGROUND

Though cochlear implant (CI) surgery is regarded as having low risk of impacting the vestibular system, several studies have documented changes in vestibular function after implantation. The mechanism of these changes is not understood. We have previously established that large, potentially damaging pressure transients can be generated in the cochlea during electrode insertion, but whether pressure transients occur within the vestibular labyrinth has yet to be determined. Here, we quantify the exposure of the vestibular system to potentially damaging pressure transients during CI surgery.

METHODS

Five human cadaveric heads were prepared with an extended facial recess and implanted sequentially with eight different CI electrode styles via a round window approach. Fiber-optic sensors measured intralabyrinthine pressures in scala vestibuli, scala tympani, and the lateral semicircular canal during insertions.

RESULTS

Electrode insertion produced a range of high-intensity pressure spikes simultaneously in the cochlea and lateral semicircular canal with all electrodes tested. Pressure transients recorded were found to be significantly higher in the vestibular labyrinth than the cochlea and occurred at peak levels known to cause acoustic trauma.

CONCLUSION

Insertion of CI electrodes can produce transients in intralabyrinthine fluid pressure levels equivalent to high-intensity, impulsive acoustic stimuli. Results from this investigation affirm the importance of atraumatic surgical techniques and suggest that in addition to the cochlea, the vestibular system is potentially exposed to damaging fluid pressure waves during cochlear implantation.

The Early Postoperative Effects of Cochlear Implantation on Horizontal Semicircular Canal Function

OBJECTIVES

To use video head impulse testing to examine the effect of cochlear implantation (CI) on horizontal SCC vestibulo-ocular reflex (VOR) gain early after surgery, and to relate outcomes to subjective imbalance.

STUDY DESIGN

Prospective cohort study.

SETTING

Academic tertiary referral center.

PATIENTS

Thirty-seven (23F:14M) adult cochlear implant recipients (mean age, 55; age range, 20-80).

INTERVENTION

Cochlear implantation.

MAIN OUTCOME MEASURE

The VOR of the horizontal semicircular canal of both the operated and non-operated ears was examined using video head impulse testing before surgery and at days 1, 7, and 28 following surgery. VOR gain, VOR gain asymmetry, and the change in VOR gain from preoperative baseline where the primary outcome measures. Subjective imbalance was assessed using a structured questionnaire.

RESULTS

VOR gain value for the operated ear was 0.88 ± 0.21. Mean VOR gain on day 1 postoperatively was 0.86 ± 0.19; on day 7, 0.87 ± 0.17, and on day 30, 0.91 ± 0.21. Before surgery median asymmery was -5.50%, on day 1 it was -5.30%, at day 7, -6.44%, and at day 30 it was -2.61%. There was no significant difference between these measures for the cohort across the four time points. Thirteen of 37 (35%) of patients experienced imbalance in the follow-up period, but this was not correlated to changes in VOR gain.

CONCLUSION

Horizontal semicircular canal function is preserved in the immediate and early postoperative period. This suggests that horizontal semicircular canal impairment is not likely to be responsible for postoperative imbalance.

Cervical vestibular evoked myogenic potential testing for assessment of vestibular functions in cochlear implant patients

This study aims to investigate the vestibular function status of cochlear implant patients using cervical vestibular evoked myogenic potential (cVEMP) testing and estimate the effects of cochlear implants on vestibular function. The cVEMPs of 50 cochlear implant patients were measured preoperatively, and at one and six months postoperatively. Then, implanted ears and non-implanted ears were compared in terms of p13/n23 wave response rates, latency, amplitude and threshold. Preoperatively, the binaural cVEMP response rate was 92%, while the cVEMP response rates of implanted ears vs. non-implanted ears at postoperative one and six months were 24% vs. 80% and 52% vs. 82%, respectively. No significant difference between implanted and non-implanted ears was found preoperatively, in terms of latent period, amplitude, or threshold. However, significant changes were found in amplitude and threshold for implanted ears after the operation, but not in latency. No significant postoperative change was found in amplitude, latent period, or threshold for non-implanted ears. Significant differences between implanted and non-implanted ears were found in both amplitude and threshold. Cochlear implants affect vestibular function, especially saccular function, and reduce the cVEMP amplitude and threshold of implanted ears.

Does cochlear implantation influence postural stability in patients with hearing loss?

BACKGROUND

Cochlear implantation (CI) procedure carries the potential risk for vestibular system insult or stimulation with resultant dysfunction due to its proximity to the cochlea. The vestibular system plays an essential role in crucial tasks such as postural control, gaze stabilization and spatial orientation.

RESEARCH QUESTION

How does standard cochlear implantation influence postural stability in patients with hearing loss?

METHODS

The study included 21 individuals (age 51 ± 18 years) qualified to undergo CI due to severe or profound hearing loss. Participants were qualified for both groups by a physician based on an interview, an otoneurological examination and vestibular tests. The first group included patients without vestibular dysfunction, whereas the other group consisted of persons with vestibular dysfunction. The research methodology included medical examinations, anthropometric measurements and stabilometry on the Biodex Balance System SD (BBS) platform. The examinations were carried out twice, i.e. prior to and 3 months post implantation. The recorded data was compared between the first and the second examination using a non-parametric Wilcoxon test. The analysis of variance (ANOVA) and Tukey's post-hoc HSD unequal sample sizes were performed for patients with and without vestibular dysfunction.

RESULTS AND SIGNIFICANCE

Study showed that 52.4% of the participants obtained results within the norm, while 47.6% scored below it. The comparison of stability indices of the examined individuals, with and without vestibular dysfunction, did not reveal statistically significant differences. The only difference was the anterior-posterior stability index assessed in static conditions. Three months after the implantation, no changes in the majority of indices were noted, with the exception of anterior-posterior stability index, which improved following the implantation. CI does not affect postural stability changes in the study participants.

Vestibular Outcome After Cochlear Implantation Is Not Related to Surgical Technique: A Double Blinded, Randomized Clinical Trial of Round Window Approach Versus Cochleostomy

To establish whether the round window approach (RWA) leads to less vestibular dysfunction and dizziness than the standard cochleostomy approach (SCA) during cochlear implant (CI) surgery, as assessed using the video head impulse test (vHIT).

Additionally, objective findings were compared with the subjective dizziness perceived by the patient.

Balance, gait and dizziness in adult cochlear implant users: A cross sectional study

Objective: Cochlear implantation is associated with vestibular impairment due to the close proximity of the structures. The aim of the study was to quantify dizziness/vertigo, gaze instability, balance and gait problems in a sample of adult cochlear implant (CI) users.Methods: An observational, cross sectional study evaluated subjective dizziness (Vestibular Rehabilitation Benefit Questionnaire (VRBQ)), balance confidence (Activities Specific Balance Questionnaire (ABC)), gait (Functional Gait Assessment (FGA) and 10m walk test), balance (Equitest Sensory Organisation Test (SOT)), and computerised dynamic visual acuity (DVA). The Dix Hallpike test was performed to test for benign paroxysmal positional vertigo (BPPV).Results: Twenty participants (n=10F), 2.8(±2.7) years post implantation, with mean age 59.3(±15.8) years were assessed. Subjective dizziness (VRBQ) was low (15.0% (±15.5)) and balance confidence was high (ABC: 82.1%±14.9). FGA scores (25.1 ± 4.4) and gait speed (1.8 (±0.3) m/sec) were below normal. Dx Hallpike was positive in 3. Gaze instability was found in 50% (DVA loss, 0.29 (± 0.16) LogMAR), while 79% demonstrated balance impairment (mean SOT score, 57.8%±14.5), with 42% falling on SOT condition 5.Discussion: Evidence of vestibular dysfunction was identified in these adult CI users.Conclusion: Access to vestibular function assessment and rehabilitation is required in adult CI users.

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.

Caloric test and video head impulse test sensitivity as vestibular impairment predictors before cochlear implant surgery

OBJECTIVES

Currently, cochlear implant procedures are becoming increasingly broad and have greatly expanded. Bilateral cochlear implants and cochlear implants are more frequently applied in children. Our hypothesis is that the video head impulse test may be more sensitive than the caloric test in detecting abnormal vestibular function before cochlear implant surgery. The objective of this study was to compare the video head impulse test and caloric test results of patients selected for cochlear implant procedures before surgery.

METHODS

The patients selected for cochlear implant surgery were submitted to a bithermal caloric test and video head impulse test.

RESULTS

By comparing angular slow phase velocity values below 5° in the bithermal caloric test (hypofunction) and video head impulse test with a gain lower than 0.8, we identified 37 (64.9%) patients with vestibular hypofunction or canal paresis and 21 (36.8%) patients with abnormal video head impulse test gain before the cochlear implant procedure. Of the 37 patients with caloric test vestibular hypofunction, 20 (54%) patients exhibited an abnormal gain in the video head impulse test.

CONCLUSION

The caloric test is more sensitive than the video head impulse test (Fisher's exact test, p=0.0002) in detecting the impaired ear before cochlear implant delivery. The proportion of caloric test/video head impulse test positive identification of abnormal vestibular function or caloric test/video head impulse test sensitivity was 1.8:1.

Assessing Gait Stability before and after Cochlear Implantation

Background

It is known that cochlear implantation may alter the inner ear and induce vestibular disorders.

Research Question

How does cochlear implantation influence gait stability? Material and Methods. An experimental group of twenty-one subjects scheduled for cochlear implantation underwent gait testing twice, on the day before cochlear implantation (BCI) and three months after cochlear implantation (ACI), using a motion capture system. A control group of 30 age-matched healthy individuals were also tested.

Results

In the experimental group, the gait stability ratio (GSR) was found to improve in 17 subjects after implantation, by an average of 6%. Certain other parameters also showed statistically significant improvement between the two experimental group tests: step time (p<0.001), single-support phase walking speed (p<0.05), and center of mass (CoM) (p<0.05). Using the CoM results of the control group, we devised a stability classification system and applied it to the pre- and postimplantation subjects. After implantation, increases were seen in the number of subjects classified in interval II (strong stability) and III (weak stability). The number of subjects in interval I (perfect stability) decreased by 1 and in interval IV (no stability) by 4.

Significance

(1) Although cochlear implantation intervenes in the vestibular area, we found evidence that gait stability improves in most subjects after the surgery, reducing the risk of falls. (2) We found statistically significant improvements in individual parameters (such as single-support phase time), in GSR, and in CoM. (3) Based on CoM results, we proposed a new rule-of-thumb way of classifying patients into gait stability intervals, for use in rehabilitation planning and monitoring.

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.

How does cochlear implantation affect five vestibular end-organ functions and dizziness?

OBJECTIVE

To evaluate all five vestibular end-organ functions (lateral, anterior, posterior semicircular canal, utricule, and saccule) and to investigate the relationship between Dizziness Handicap Inventory (DHI) and vestibular functions prior to CI (cochlear implantation) and at postoperative day 3 and month 3.

METHODS

A total of 42 patients (age 16-70years) with normal vestibular functions preoperatively and undergoing unilateral CI were included in this prospective descriptive study. Video head impulse test (vHIT) for three semicircular canal (SSC) functions, ocular vestibular-evoked myogenic potential (oVEMP) for utricule function, cervical vestibular-evoked myogenic potential (cVEMP) for saccule function and DHI for subjective vertigo symptoms were performed prior to CI and at postoperative day 3 and month 3.

RESULTS

There was a significant impairment of vestibular function in 12 patients (28.5%) on the implantation side and significant DHI increase was observed in 13 of 42 (30.9%) patients at postoperative day 3 after CI (p<0.05). We found SSC dysfunction in 7 patients (16,6%) who underwent observation with vHIT, saccule dysfunction in 8 patients (19%) with cVEMP and utricule dysfunction in 5 patients (11.9%) with oVEMP on the operated side 3days after surgery (p<0.05). Posterior SSC functions (5 patients) were more affected than lateral SSC functions (3 patients). At postoperative month 3, six patients (14.2%) still had deteriorating results in the objective tests and significant DHI increase was continued in 4 (9.5%) patients (p<0.05). The deterioration in vHIT continued in only 1 (2.3%) patient (p>0.05). The deterioration in cVEMP continued in 5 (11.9%) patients (p<0.05). The deterioration in oVEMP continued in 2 (4.7%) patients (p>0.05). There was a significant correlation between DHI and objective vestibular tests both in the early and late postoperative period (r=0.795; p<0.05).

CONCLUSION

Our study showed that both canal and otolith functions can be damaged after CI especially in the early postoperative period. Surprisingly, posterior SSC functions were more affected than lateral SSC. Therefore, a gold standard vestibular test battery that can evaluate each of three SSC canals and two otoliths functions is essential. Since a single vestibular test for this purpose is not available, we recommend the use of the three available vestibular tests together. This test battery, which is capable of evaluating five vestibular end-organ functions in preoperative and postoperative vestibular evaluations, can provide more accurate results not only for CI but also for most otologic surgeries.

Vestibular dysfunction and postural balance in cochlear implant users: a narrative literature review

ABSTRACT Cochlear implants directly stimulate nerve fibers and ganglion cells of the auditory nerve, which transform sound energy into low levels of electrical current, stimulating the remaining fibers of the auditory nerve in patients with severe to profound hearing loss, in order to provide the significant range of auditory sensation and speech comprehension. Due to the close relationship between cochlea and vestibular receptors, some patients may present vestibular and postural balance changes concomitantly after surgery. This study aimed to perform a narrative review of the main studies that relate vestibular symptoms in patients implanted in the last six years. The research was performed through the databases: SciELO, LILACS and PubMed, using associated descriptors for "cochlear implant", "vestibular dysfunction", "vertigo" and "balance", totalizing 21 studies that fitted the inclusion criteria. The results were described in a chronological order of publication, showing the main conclusions. Of the total studies analyzed, 18 related vestibular function to cochlear implant and only 3 studies did not find such a relationship. The literature characterize the effects of the cochlear implant on the vestibular system, however, the results are contradictory.

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.

Anatomic Variations in Temporal Bones Affect the Intensity of Nystagmus During Warm Caloric Irrigation

HYPOTHESIS

Anatomic variables within the mastoid will correlate with intensity of caloric responses.

BACKGROUND

During caloric irrigation, heat is transferred from the external auditory canal to the lateral semicircular canal (LSCC) through aerated mastoid bone. Temporal bone airspace volume and bone volume vary widely but the effect of this variation on caloric irrigation testing is not well characterized. Understanding this effect is necessary to understand how mastoid surgery may alter caloric irrigation results.

METHODS

Twenty-two mastoid airspace and bones, as well as LSCC, were reconstructed from computed tomography scans of 11 subjects with normal anatomy who underwent vestibular function evaluation. Respective surface area (SA) and volume (V) of the mastoid airspace, bones, LSCC, and distance from LSCC to tympanic membrane (LSCC-TM) were calculated. In addition, computed values from these anatomic structures were correlated with the maximum velocity of slow phase nystagmus during warm caloric irrigation (MVwarm).

RESULTS

Our results showed that the combined effect of airspace SA:V, bone SA:V, LSCC SA:V, and LSCC-TM distance accounted for 69.5% of the variation in MVwarm. Airspace SA:V (R = 0.22) and LSCC SA:V (R2 = 0.02) positively correlated with MVwarm, while bone SA:V (R = 0.17) demonstrated an inverse correlation with MVwarm.

CONCLUSION

Preliminary results from this pilot study suggest that a substantial amount of the variability in MVwarm can be explained by temporal bone anatomy. Results also indicate that the denser the bone, the more heat is transferred to the LSSC, whereas increased airspace serves as an insulator. A larger study is necessary to confirm our findings.

Effect of cochlear implant surgery on vestibular function: meta-analysis study

Importance

Vestibular disorders have been reported following cochlear implant (CI) surgery, but the literature shows a wide discrepancy in the reported clinical impact. The aim of this meta-analysis is to quantify the effect of CI before and after surgery on the outcomes of vestibular tests, postural stability, and subjective perception of dizziness.

Objective

To evaluate the effects of CI surgery on vestibular function in adult patients (≥18 years) with sensorineural hearing loss who underwent unilateral or bilateral implantation.

Data sources

MEDLINE, PubMed, Web of Science and Cochrane Library from January 1, 1995, through July 12, 2016.

Study selection

Published studies of adult patients who received unilateral or bilateral CIs and whose vestibular function or postural stability was assessed before and after surgery.

Data extraction

From each study, test results before and after surgery were compared, for the following five tests: clinical head impulse test (HIT); bi-thermal caloric irrigation of the horizontal semicircular canal; vestibular evoked myogenic potential (VEMP); dizziness handicap inventory (DHI); and computerized dynamic posturography (CDP).

Results

Twenty-seven studies met all inclusion criteria. Most studies performed either bi-thermal caloric irrigation and/or VEMP, with fewer studies investigating changes in HIT, posturography or DHI. CI surgery significantly affected the results of caloric and VEMP testing. However, HIT results, posturography, and DHI, scores were not significantly affected after CI surgery.

Conclusions and relevance

CI surgery has a significant negative effect on the results of caloric as well as VEMP tests. No significant effect of CI surgery was detected in HIT, posturography, or DHI scores. Overall, the clinical effect of CI surgery on the vestibular function was found to be insignificant. Nonetheless, the potential effects of surgery on the vestibular system should be discussed with CI candidates before surgery.

Preliminary results of video Head Impulse Testing (vHIT) in children with cochlear implants

OBJECTIVE

To evaluate the lateral semicircular canal high frequency vestibulo-oculomotor reflex (LSC HF VOR) in children with cochlear implant.

METHODS

16 children (10 females and 6 males, age range = 5-17 years) receiving a unilateral (n = 12) or a bilateral (n = 4) cochlear implant were included and compared to a control group of 20 age-matched normal-hearing (NH) children. Both implanted and NH children received a vestibular function test battery, including a Vestibulo-Ocular Reflex (VOR) gain assessment by means of a video-Head Impulse Test (vHIT), which represented the main outcome measure. In implanted subjects, vHIT was measured on both sides in the "CI-ON" and "CI-OFF" conditions.

RESULTS

Overall, no significant LSC HF VOR gain difference was found between CI users and NH peers. In the unilaterally implanted group, the LSC HF VOR gain measured in the "CI-ON" condition was significantly higher than in the "CI-OFF" condition, both in the implanted and in the non-implanted ear. In the bilaterally implanted group there was no such a difference between the two conditions, on either side.

CONCLUSION

This is the first study investigating the LSC HF VOR gain in children with unilateral and bilateral CI. The study demonstrates that the LSC HF VOR of bilaterally implanted children is comparable to normal hearing children.

What vestibular tests to choose in symptomatic patients after a cochlear implant? A systematic review and meta-analysis

Vestibular function after cochlear implantation is difficult to understand, as subjective vestibular symptoms seem uncorrelated with the results of objective tests. Consequently, clinicians may struggle to decide what assessments to perform for a symptomatic patient. We used a systematic review and meta-analysis approach to enlighten this point. After a study inclusion process, results were classified into four different groups for each test in each study: (1) 'true positive' if the test showed impairment from pre-operative to post-operative in symptomatic patients; (2) 'false positive' if the test showed impairment from pre-operative to post-operative in asymptomatic patients; (3) 'true negative' if the test showed no impairment in asymptomatic patients; and (4) 'false negative' if the test showed no impairment in symptomatic patients. From these groups, sensitivities and specificities of each test were calculated in a meta-analysis. After reviewing more than 3000 references, 16 studies were included, representing 957 patients. The meta-analysis revealed a sensitivity of 0.21 (CI 95 % 0.08-0.40) for the caloric tests, of 0.32 (CI 95 % 0.15-0.54) for the cervical vestibular evoked myogenic potentials (c-VEMP), and of 0.5 (CI 95 % 0.07-0.93) for the head impulse tests. The analysis of prevalence revealed that c-VEMPs were the most often impaired, and the HIT the most often conserved. Our review and meta-analysis revealed that no vestibular test is sensitive enough to be recommended as a single test. Ideally, all the five vestibular sensors should be tested. In clinical practice, we suggest a case-to-case strategy according to patient's symptoms and their suspected origin.

Effects of Unilateral Cochlear Implantation on Balance Control and Sensory Organization in Adult Patients with Profound Hearing Loss

Many studies were interested in the consequence of vestibular dysfunction related to cochlear implantation on balance control. This pilot study aimed to assess the effects of unilateral cochlear implantation on the modalities of balance control and sensorimotor strategies. Posturographic and vestibular evaluations were performed in 10 patients (55 ± 20 years) with profound hearing loss who were candidates to undergo unilateral multichannel cochlear implantation. The evaluation was carried out shortly before and one year after surgery. Posturographic tests were also performed in 10 age-matched healthy participants (63 ± 16 years). Vestibular compensation was observed within one year. In addition, postural performances of the patients increased within one year after cochlear implantation, especially in the more complex situations, in which sensory information is either unavailable or conflicting. Before surgery, postural performances were higher in the control group compared to the patients' group. One year after cochlear implantation, postural control was close to normalize. The improvement of postural performance could be explained by a mechanism of vestibular compensation. In addition, the recovery of auditory information which is the consequence of cochlear implantation could lead to an extended exploration of the environment possibly favoring the development of new balance strategies.

The Effects of Aging on Clinical Vestibular Evaluations

Balance disorders are common issues for aging populations due to the effects of normal aging on peripheral vestibular structures. These changes affect the results of vestibular function evaluations and make the interpretation of these results more difficult. The objective of this article is to review the current state of knowledge of clinically relevant vestibular measures. We will first focus on otolith function assessment methods cervical-VEMP (cVEMP) and ocular-VEMP (oVEMP), then the caloric and video-head impulse test (vHIT) methods for semicircular canals assessment. cVEMP and oVEMP are useful methods, though research on the effects of age for some parameters are still inconclusive. vHIT results are largely independent of age as compared to caloric stimulation and should therefore be preferred for the evaluation of the semicircular canals function.