Vestibular function and cochlear implant

[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.

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 Preservation After Cochlear Implantation Using the Round Window Approach

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

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

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

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

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.

Long-Term Lateral Semicircular Canal Function in Children with Cochlear Implants: Results of Video Head Impulse Test

In children with profound deafness, bilateral cochlear implant (CI) is an effective, established procedure. However, its safety on vestibular function has recently been debated. The goal of this study is to evaluate the long-term lateral semicircular canal high-frequency vestibulo-oculomotor reflex (LSC HF VOR) in children with CI by video head impulse testing (vHIT). This is a cross-sectional study assessing a cohort of children who received either a unilateral (12) or a bilateral (12) cochlear implant (CI), compared with a control group of 12 normal-hearing children. No significant LSC HF VOR gain difference was found between CI users and controls. 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, the difference between the two conditions was not significant. Our results do not show any impairment of LSC HF VOR function in children with CI compared to normal-hearing children in the long-term period. This suggests that both unilateral and simultaneous/sequential bilateral CI are procedures that do not impair HF LSC long-term function when analyzed by vHIT.

Sensory processing disorders in children with hearing impairment: Implications for multidisciplinary approach and early intervention

OBJECTIVE

To explore the differences in sensory processing between children with hearing impairments and children with normal hearing and the variables that influence sensory processing disorder (SPD).

METHODS

The sensory processing abilities of 90 children were compared in three age-matched groups of 30, with cochlear implants (CIs), hearing aids (HAs), and normal hearing (NH). The Arabic Sensory Profile (Arabic_SP) was used.

RESULTS

Findings were presented in the Arabic_SP section and factor levels. Sections: The NH group performed better (p < .05) than the CI group in 57% of the sections and better than the HA group in 14%. The CI group exhibited more signs of SPD than the HA group with vestibular processing, multisensory processing, and emotional-social responses.

FACTORS

The NH group differed from the CI group on all the factors that showed significance and from the HA group with inattention/distractibility and poor registration. There were great differences between the CI and the HA groups on all the factors except with poor registration and fine motor/perceptual. Hearing loss variables that most affected results in the Arabic_SP were the age at receiving a hearing device and type of hearing loss onset.

CONCLUSION

Along with speech and language problems, children with hearing impairment are especially vulnerable to SPD. Children with CIs and HAs are increasingly susceptible to auditory processing disorders. Higher risks of balance, multisensory processing, social-emotional, and fine motor problems are in children with CIs. Increased SPD risks came with a higher age at implantation. Findings indicate the importance of a multidisciplinary approach for early detection and intervention for children with hearing impairment, especially those with CIs.

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.

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.

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

Objectives/Hypothesis

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

Study Design: Prospective case series.

Methods

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

Results

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

Conclusions

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

Level of Evidence

4 Laryngoscope, 2020

Vestibular status in partial deafness

Introduction

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

Objective

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

Methods

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

Results

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

Conclusion

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

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.

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.

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.

Sudden onset of static equilibrium dysfunction in patients receiving a cochlear implant

BACKGROUND

We investigated the sudden onset of static equilibrium dysfunction caused by cochlear implantation (CI) in congenital hearing loss patients.

METHOD

Twenty-five patients were selected from a cohort of unilateral CI recipients to form the CI group. Static posturography was performed 1 to 3 days before and 3 to 5 days after CI. Each patient underwent the test with eyes open (EO) and eyes closed (EC) for 30 seconds, separately. Another group of age- and sex-matched patients with no history of hearing impairment undergoing unrelated surgeries formed the control group, and were examined with the same tests pre- and post-surgery. A third group of patients undergoing middle ear surgery formed the otitis media (OM) group. Postural sway parameters including sway velocity (SV) in the X-axis, SV in the Y-axis, length of sway locus length (LNG), and environmental area (ENV) were measured and recorded.

RESULTS

Comparison of pre-surgery posturographical parameters between the CI and control groups revealed no significant differences. Significant differences were found in most parameters in pre- and post-surgery comparisons in the CI group. Mean SV values in the X-axis pre- and post-surgery were 8.48 and 11.52 mm/s, respectively, in the EO condition (P < .05), and 14.94 and 20.16 mm/s, respectively, in the EC condition (P < .05). In the Y-axis, mean SV values were 15.36 and 20.24 mm/s pre- and post-surgery, respectively, in the EC condition (P < .05). The LNG values in the CI group pre- and post-surgery were 319.60 and 469.88 mm in the EO condition (P < .05), and 571.40 and 764.12 mm in the EC condition (P < .05). No significant functional equilibrium change was observed in the control group between pre- and post-surgery (P > .05) except SV in the X-axis and LNG in the EO condition (P < .05). No significant pre- and post-surgery differences were found in the OM group.

CONCLUSION

CI appeared to influence static equilibrium function within 1 week post-surgery. This influence was greater when eyes were closed.

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.

Sensorimotor interaction in deaf children. Relationship between gait performance and hearing input during childhood assessed in pre-lingual cochlear implant users

CONCLUSIONS

The results suggest that auditory input is not neutral in motor skills and the complex interaction between them is generated in the earlier stages of childhood development. Objective The assessment of gait performance in pre-lingual deaf children with cochlear implant (CI).

METHODS

Gait velocity (GV), using a 10-meter test, was measured by means of three inertial sensors in 10 pre-lingual cochlear implant users (CIU) (10-16 years old) in three sensory conditions: (1) cochlear implant turned on with environmental noise (EN), (2) cochlear implant turned on with EN and with cognitive dual task (DT), and (3) CI turned off (CI-OFF). GV with EN and DT was assessed in a normal hearing control group (CG) (n = 14). Mann-Whitney and Wilcoxon Signed ranked test were used for significance validation.

RESULTS

(1) GV in CG was lower in DT than with EN (p = .019). (2) GV was faster in CG with EN compared with the three conditions in CIU (EN, p = .006; DT, p = .0001; CI-OFF, p = .03). (3) CIU had slower GV walking with EN (p = .037) and with DT (p = .022). (4) Dividing the CIU sample by age, the acoustic information generates a slower gait for those implanted after 3 years old.

The effects of cochlear implantation on vestibular function in 1-4 years old children

OBJECTIVES

Although cochlear implants offer an effective hearing restoration option in children with severe to profound hearing loss, concern continues to exist regarding the possible effects of cochlear implantation on the vestibular system and balance.

METHODS

In a prospective cohort study, 27 children with bilateral profound hearing loss (all candidates for cochlear implantation) were evaluated for their vestibular function before and after cochlear implantation. Vestibular evaluations consisted of Vestibular Evoked Myogenic Potentials, caloric testing and the Head-Impulse Test.

RESULTS

Mean age at the time of cochlear implantation was 27.19 months. Without considering vestibular evaluation results, one of the ears was selected for surgery. Vestibular tests after surgery were not indicative of any statistically significant change in vestibular system or balance.

CONCLUSION

This limited data shows that cochlear implantation did not impair the vestibular system of these patients. By the results of our study we may conclude that round window implantation does not have any disturbing impact on vestibular function in children. The generalization of this result needs further research.

[The Heidelberg CI database module : Quality control in hearing restoration with cochlear implants]

BACKGROUND

Cochlear implants (CI) have been established as the therapy of choice for functional deafness. The number of CI-rehabilitated patients is continuously growing. The resulting data can provide important information for physicians, health insurance companies, and scientists. Assessment and structuring of data becomes more feasible with the application of modern database systems.

MATERIALS AND METHODS

In collaboration with Innoforce Est., Liechtenstein, the authors developed a database module for the specific needs of CI patients. Data of 100 patients were included and evaluated. The main features of the module and an example data analysis are presented.

RESULTS

Analysis of data from these 100 patients reveals 50 men and 50 women aged between 1 and 87 years, with a maximum value in the 51-60-years age group. More than 50% of the patients were also severely hearing impaired in the contralateral ear and fitted the CI indication criteria. Functional deafness in the ear subsequently fitted with CI in most of the patients had arisen more than 20 years previously. Preoperative diagnostic electrical stimulation of the cochlear nerve was positive in 67 patients. All 100 patients perceived auditory sensations with the CI.

CONCLUSION

The presented patient cohort is representative of patients at the Department of Otorhinolaryngology, University of Heidelberg Medical Center, Germany, and the demographic distribution is in accordance with the literature. The state of the contralateral ear, often also fitting the CI indication, is not surprising, as cochlear implantation is a comparatively new procedure. Preoperative electrical stimulation turned out not to be significant by itself. The hearing results and overview of complications were easy to calculate in comparison to a pure data storage system such as i.s.h.med.

Otolithic organ function in patients with profound sensorineural hearing loss

Profound sensorineural hearing loss (PSHL) is not uncommonly encountered in otology. In clinics, there is a high incidence of otolithic damage in patients with PSHL, but relevant reports are few. Sharing a continuous membranous structure and similar receptor cell ultrastructures, the cochlea and vestibule may be susceptible to the same harmful factors. Disorders of the inner ear may result in a variety of manifestations, including vertigo, spatial disorientation, blurred vision, impaired articulation, and hearing impairment. Considering the diversity of clinical symptoms associated with PSHL with otolithic dysfunction, it may be frequently misdiagnosed, and objective means of testing the function of otolithic organs should be recommended for hearing-impaired patients. Vestibular-evoked myogenic potentials (VEMPs) via air-conducted sound are of great importance for the diagnosis of otolithic function. Hearing devices such as cochlear implants are commonly accepted treatments for PSHL, and early identification and treatment of vestibular disorders may increase the success rate of cochlear implantation. Therefore, it is necessary to increase awareness of otolithic functional states in patients with PSHL.

Dexamethasone Is One of the Factors Minimizing the Inner Ear Damage from Electrode Insertion in Cochlear Implantation

The aim of this study was to investigate the efficacy of preoperative and intraoperative steroid administration for inner ear protection in cochlear implantation (CI). Nineteen subjects who underwent CI were included in the study, and 10 subjects were enrolled as controls (steroid-administered group, n = 19; control group, n = 10). Dexamethasone (dexamethasone sodium phosphate, 5 mg/ml) was systemically administered preoperatively (1 ml) and topically applied during CI (0.5 ml). The extent of hearing preservation (HP) after CI and the change in the bithermal caloric response were evaluated. Hearing level was calculated using mean thresholds [(250 Hz + 500 Hz + 1,000 Hz + 2,000 Hz)/4]. Preoperative hearing thresholds were similar in the steroid-administered and control groups (100.92 ± 12.60 vs. 103.29 ± 14.39 dB, p = 0.650). The mean thresholds significantly increased in both groups after surgery (108.46 ± 14.08 dB, p = 0.006, for the steroid-administered group; 117.50 ± 6.34 dB, p = 0.027, for the control group), and the difference between the groups was also significant (p = 0.027). The postoperative shift in the hearing thresholds at frequencies of 500 and 1,000 Hz was significant in the steroid-administered group and that at the frequencies of 500, 1,000 and 2,000 Hz was significant in the control group. However, the extent of the shift in hearing threshold levels at each frequency was not significantly different between the groups. Preservation of hearing thresholds was compared between the groups, and there were significantly more subjects with complete and partial HP in the steroid-administered group than in the control group (p = 0.008). The preoperative caloric response was maintained after CI in the steroid-administered group. This study suggests that the perioperative use of a steroid could minimize the inner ear damage after CI.

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.

Vertigo and dizziness in children

Vertigo and dizziness of at least moderate severity occur in >5% of school-aged children and cause considerable restrictions in participation in school and leisure activity. More than 50% of dizzy children also have headache. Vestibular migraine and benign paroxysmal vertigo as a migraine precursor are the most common diagnoses in dizziness clinics for children and adolescents. They account for 30-60% of diagnoses. Other common causes are somatoform, orthostatic, or posttraumatic dizziness. All other disorders that are known to cause vertigo and dizziness in adults also occur in children, but incidence rates are usually lower. The vestibular and balance systems are largely developed after 1 year of age. Therefore, clinical and laboratory testing is reliable. Brain magnetic resonance imaging to exclude severe conditions, such as a brainstem tumor, is necessary only if clinical - in particular, ocular motor - testing is abnormal. Most conditions causing vertigo and dizziness in childhood and adolescence are treatable. Nonpharmacologic prophylaxis should always be recommended in vestibular migraine. Behavioral support is useful in somatization. Evidence for the effectiveness of drug therapy is largely based on experience in adult populations. High-quality controlled studies in childhood cohorts are sparse. It is important to make a correct diagnosis early on, as counseling and appropriate treatment may avoid chronic illness.

Impairment of Caloric Function After Cochlear Implantation

PURPOSE

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

METHOD

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

RESULTS

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

CONCLUSIONS

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