Dizziness and vestibular function before and after cochlear implantation

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.

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.

A case series shows independent vestibular labyrinthine function after major surgical trauma to the human cochlea

Background

The receptors for hearing and balance are housed together in the labyrinth of the inner ear and share the same fluids. Surgical damage to either receptor system was widely believed to cause certain permanent loss of the receptor function of the other. That principle, however, has been called into question because there have been anecdotal reports in individual patients of at least partial preservation of cochlear function after major surgical damage to the vestibular division and vice versa.

Methods

We performed specific objective vestibular function tests before and after surgical trauma (partial or subtotal cochlear removal) for treatment of intracochlear tumors in 27 consecutive patients in a tertiary referral center. Vestibular function was assessed by calorics (low-frequency response of the lateral semicircular canal), vestibulo-ocular reflex by video head impulse test (vHIT) of the three semicircular canals, cervical and ocular vestibular evoked myogenic potentials (cVEMP, saccule and oVEMP, utricle). Preoperative and postoperative distributions were compared with paired t-tests.

Results

Here we show that there was no significant difference between pre- and post-operative measures for all tests of the five vestibular organs, and that after major surgical cochlear trauma, the vestibular receptors continue to function independently.

Conclusions

These surprising observations have important implications for our understanding of the function and the surgery of the peripheral auditory and vestibular system in general and open up new possibilities for the development, construction and evaluation of neural interfaces for electrical or optical stimulation of the peripheral auditory and vestibular nervous system.

Plontke et al. report data on the preservation of vestibular function in a series of patients undergoing surgical removal of intracochlear tumors. Using objective clinical tests, the authors show that in most patients the vestibular system can function normally despite major surgical trauma to the cochlea.

Receptors for the hearing and balance systems are located in the inner ear. These are very delicate structures that convert sound and movement into nerve signals to control hearing and balance. Surgical damage to either system was widely believed to cause loss of function in the other. Here, we investigated the function of the balance receptors before and after severe damage to the part of the inner ear which is responsible for hearing (the cochlea) due to surgical removal of tumurs. We show that despite the close proximity of both types of receptors and the severe trauma to the cochlea, in most patients the balance system can still function normally. This observation may have important implications for how we treat patients with inner ear surgery and for the techniques we use to treat hearing and balance disorders.

Vestibular Physical Therapy and Fall Risk Assessment

Vestibular physical therapy (VPT) is a specialized form of evidence-based therapy designed to alleviate primary (vertigo, dizziness, imbalance, gait instability, falls) and secondary (deconditioning, cervical muscle tension, anxiety, poor quality of life, fear of falling/fear avoidance behavior) symptoms related to vestibular disorders. This article provides an overview of VPT, highlighting various exercise modalities used to treat a variety of vestibular disorders. Patient safety and fall prevention are paramount; therefore, fall risk assessment and treatment are also addressed.

Vestibular Function After Bilateral Simultaneous Cochlear Implantation

OBJECTIVES

Thanks to the advantages of hearing-in-noise and spatial orientation, currently bilateral cochlear implantation (CI) became popular for patients with profound hearing loss. The aim of this study was to investigate vestibular function in bilateral simultaneous CI recipients.

STUDY DESIGN

Retrospective analysis.

SETTING

University hospital.

PATIENTS

Sixteen patients with profound hearing loss were included.

INTERVENTIONS

Bilateral simultaneous CI with flexible electrode using round window approach.

MAIN OUTCOME MEASURES

Vestibular function was evaluated using both objective and subjective measures in the subjects preoperatively and 4 months postoperatively. Differences were analyzed preoperatively and postoperatively.

RESULTS

Preoperative vestibular tests revealed that 8 subjects (50%) had abnormal caloric test results, 11 ears (34.4%) had abnormal ocular vestibular-evoked myogenic potential results, 6 ears (18.8%) had abnormal cervical vestibular-evoked myogenic potential results, 7 ears (21.9%) in the anterior semicircular canal, and 6 ears (18.8%) in the posterior semicircular canal had gain loss. However, surgery significantly decreased the sums of the maximal slow-phase velocities evidenced by caloric test (p ‹ 0.05). Cervical vestibular-evoked myogenic potential abnormal rate significantly increased to 53.1% after surgery (p ‹ 0.05). The postoperative changes regarding ocular vestibular-evoked myogenic potential, video head impulse test (vHIT), and Dizziness Handicap Inventory (DHI) were not significant among all the patients. Patients diagnosed as large vestibular aqueduct syndrome showed significantly higher DHI scores than others (p ‹ 0.05). Spearman's correlation analysis revealed that DHI moderately correlated with the dysfunction of semicircular canals evidenced by vHIT (r = 0.702; p < 0.001), weakly correlated with caloric (r = 0.352; p = 0.048). However, no correlation was found between DHI and VEMPs. The monosyllabic and disyllabic word recognition score significantly improved from 0 to 60.4 ± 14.3% (p < 0.05) and from 0 to 63.3 ± 14.5% (p < 0.05) respectively. There was no correlation between the improvement of word recognition score and the change of vestibular tests.

CONCLUSION

The study showed preservation of utricle function, vestibular function at high frequency after bilateral simultaneous CI. However, operation significantly affected vestibular function at low frequency and saccule function. Patients with large vestibular aqueduct syndrome showed dramatically higher DHI scores than others. DHI moderately correlated with vHIT and weakly correlated with caloric.

Vestibular Function After Cochlear Implantation in Partial Deafness Treatment

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

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

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

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

Vestibular 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.

Relative efficacy of veria and mastoidectomy techniques of cochlear implantation in preservation of sound-induced saccular responses

OBJECTIVE

Cochlear implantation (CI) is a safe technique to give hearing sensation to a person with hearing impairment. The present study aimed to compare the two surgical approaches of CI, mastoidectomy and veria, for their effects on saccular function assessed using cervical vestibular-evoked myogenic potential (cVEMP).

DESIGN

Multiple group time series design.

STUDY SAMPLE

The study included 63 children (3-8 years old) who underwent CI using veria technique (n = 20) and mastoidectomy approach (n = 43). The 500-Hz tone-burst evoked cVEMP were recorded on three occasions- a day before CI surgery, a day after the device switch-on and 4 months after the switch-on.

RESULTS

The post-implant results revealed the absence of cVEMP in nearly 40% of the participants. The amplitudes were significantly lower at the time of the switch-on and at the 4-months follow-up period (p < 0.05). Among the participants undergoing CI using mastoidectomy approach, amplitudes were significantly larger after surgery than those undergoing surgery using veria technique (p < 0.05).

CONCLUSIONS

The saccular responses are better preserved with the mastoidectomy technique than the veria technique for CI surgery.

Postural control characterization according to age and auditory input in cochlear implant users

Aims/Objectives: Understand the relationship between auditory input and balance motor control. Material and Methods: Twelve prelingual adolescent cochlear implant users (CIU) and 12 adult postlingual CIU were tested by posturography on a force platform with eyes open in two conditions, with the cochlear implant (CI) on and off. Energy consumption (EC) of the body center of pressure sway signal was measured, calculating total EC and divided into three bands of frequencies; low (B1) 0-0.1 Hz, medium (B2) 0.1-1 Hz, and high (B3)1-2 Hz. Wilcoxon and Mann-Whitney tests were used for statistical analysis and the significance level was P ≤ 0.05. Results: Prelingual CIU decrease the EC in low and high frequencies throughout the adolescence (P < 0.05) assessed with the CI turned on, while it did not show any modification with the CI off. Postlingual CIU showed a deterioration of PR related to aging when evaluated with the CIU turned off, P < 0.05 in band 1. However, with the CI turned on they had no significant increase in this age range. Conclusions and Significance: The acoustic input improved EC of postural responses in higher and lower frequencies in adolescence and with aging which suggests a relationship with gross and fine movements involved in postural control.

Changes in Vestibular Symptoms and Function After Cochlear Implantation: Relevant Factors and Correlations With Residual Hearing

Objectives

The aim of this study was to evaluate vestibular function loss after cochlear implantation (CI) and the relationship between vestibular function and hearing changes.

Methods

Seventy-five patients with CI were enrolled and divided into those with normal preoperative caloric function (group I) and those with a normal preoperative waveform in cervical vestibular evoked myogenic potential (c-VEMP) testing (group II). The relationship between hearing and changes in the vestibular system was analyzed preoperatively and at 3 and 6 months postoperatively.

Results

In group I, unilateral weakness on the implanted side was detected in five (7.7%) and eight (12.3%) patients at 3 and 6 months post-CI, respectively. By 3 months post-CI, the total slow-phase velocity (SPV; warm and cold stimulations) was significantly different between the implanted and non-implanted sides (P=0.011), and the shift in total SPV from pre- to post-CI was significantly correlated with the average hearing threshold at 6 months post-CI. In group II, an abnormal c-VEMP was detected on the implanted side in six patients (16.2%) at 3 months post-CI, and in six patients (16.2%) at 6 months post-CI. Significant changes were noticed in the P1 and N1 amplitude at 3 months postCI (P=0.027 and P=0.019, respectively).

Conclusion

Vestibular function and residual hearing function should be afforded equal and simultaneous consideration in terms of preservation.

Episodic Vestibular Symptoms in Children With a Congenital Cytomegalovirus Infection: A Case Series

OBJECTIVE

Congenital cytomegalovirus (cCMV) infection is the most common non-genetic cause of sensorineural hearing loss in children. Although cCMV-induced vestibular loss is demonstrated in several studies, the occurrence of vertigo has been described in only two cases to date. The aim of this paper is to discuss the underlying pathophysiology of recurrent vestibular symptoms in children with cCMV, based on five cases investigated in our center and an extensive research of the literature.

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary referral center.

PATIENTS

This case series describes five pediatric cCMV-patients (three boys, two girls). Four of them were symptomatic at birth, one was asymptomatic. Three patients underwent cochlear implantation. The age of onset of the vestibular symptoms varied from 2;0 to 7;3 years of age.

INTERVENTION

None.

MAIN OUTCOME MEASURES

Details regarding the patient history and results of cranial imaging, audiological, vestibular, and neurological assessments were collected retrospectively.

RESULTS

The selected cases suffered from recurrent vestibular symptoms. All patients had delayed onset, fluctuating, and/or progressive hearing loss. In all cases, the attacks were accompanied with nausea and vomiting and occurred without clear-cut trigger. Migraine and epilepsy often were proposed as first diagnosis, although they could not be confirmed eventually. Four out of five patients were diagnosed with a peripheral vestibular deficit.

CONCLUSIONS

Diagnosis of vestibular symptoms in children with cCMV is complex, given the multiple morbidities than can occur. Peripheral vestibular causes should be considered in the diagnosis, as important vestibular deficits are demonstrated in this population.

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.

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.

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

Purpose

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

Methods

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

Results

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

Conclusions

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

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.

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.

Impact of cochlear implantation on peripheral vestibular function in adults

OBJECTIVE

Cochlear implantation may have a detrimental effect on vestibular function and residual hearing. Our goal was to investigate the impact of cochlear implantation on peripheral vestibular function and the symptomatology that ensues.

MATERIAL AND METHODS

A prospective observational study included all adults undergoing cochlear implantation by the same operator between July 2014 and December 2015, with pre- and postoperative (4 months) neurovestibular balance examination comprising a questionnaire and clinical tests [head impulse test (HIT), head-shaking test (HST), skull vibration test (SVT)] and instrumental tests [caloric test of the lateral semicircular canal and cervical vestibular-evoked myogenic potentials (cVEMP)].

RESULTS

Twenty-two patients were included, with a mean age of 62 years and sex-ratio of 1.2. Before implantation, 50% of subjects (n=11) reported at least one episode of vertigo associated with balance disorder during their life. After implantation, there were 11 cases of vertigo but only one patient described persistent discomfort related to vertigo 4 months after surgery. Patients with impaired vestibular function after 4 months, taking all symptoms together, were all aged more than 75 years. HIT was abnormal in 18% of cases before implantation and in 59% after (P=NS). HST showed nystagmus in one patient both before and after surgery. Only 18% of patients showed nystagmus induced by SVT before surgery, increasing to one-third after surgery (P=NS). Caloric test of the lateral canal showed hypofunction in 50% of cases before surgery, including 10% of cases with areflexia. This rate increased after surgery to 58%, with 18% areflexia (P=NS). cVEMPs were not detected in 68% of cases before implantation and this rate increased to 86% after surgery (P=NS). There were no significant associations (P>0.05) between test results and symptoms.

CONCLUSIONS

In the medium term, although older subjects more frequently presented vestibular disorder, cochlear implantation induced little vertigo or balance disorder, sometimes even improving vestibular function. However, vestibular disorders were frequent preoperatively and increased postoperatively. We tested vestibular function on different stimulation frequencies and yet found no correlation between postoperative test results and postoperative vertigo.

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.

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.