Vestibular stimulation after cochlear implantation in common cavity deformity

Vestibular anomalies and dysfunctions in children with inner ear malformations: A narrative review

About 20% of children with congenital hearing loss present malformations of the inner ear. In the past few years much has been understood about the morphology and function of the anterior part of the labyrinth, since hearing loss may have a dramatic effect on the overall development of a child. Nowadays, for most of them, a chance for hearing rehabilitation is available, making hearing loss a treatable condition. The anomalies range from the lack of development of the whole inner ear to specific anomalies of isolated structures. Despite the frequent concomitant involvement of the posterior part of the labyrinth, this part of the inner ear is frequently neglected while discussing its morphology and dysfunction. Even though vestibular and balance function/dysfunction may have a significant impact on the global development of children, very little is known about these specific disorders in patients with inner ear malformations. The aim of this review is to summarize the available literature about vestibular anomalies and dysfunctions in children with inner ear malformations, discussing what is currently known about the topic.

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.

Application of Multiplanar Volume Reconstruction Technique for the Assessment of Electrode Location and Analysis of the Correlation to Cochlear Programming and Performance in Common Cavity Deformity

Purpose: Owing to the characteristic anatomy, cochlear implantation (CI) for common cavity deformity (CCD) has resulted in varied outcomes and frequent facial and vestibular nerve stimulation. The current study analyzed the correlation among the distance between each electrode and cavity wall (abbreviation, D), programming parameters, and performances outcomes.

Materials and Methods: The current, retrospective study included 25 patients (27 ears) with CCD underwent CI. The multiplanar volume reconstruction (MPVR) techniques were employed to reconstruct and evaluate the postoperative temporal bone CT. The D and maximum comfortable level (MCL) 6 months after CI, facial and vestibular nerve stimulation, and outcomes 1, 2, and 3 years after CI pertaining to the questionnaires were documented and analyzed.

Results: The patients were divided into symptomatic (10, 37%) and asymptomatic (17, 63%) groups according to with or without facial and vestibular nerve stimulation. The MCL pertaining to the symptomatic group was significantly lower than asymptomatic group, but Categories of Auditory Performance (CAP) scores 1 year after surgery was better (p < 0.05). The subjects were divided into flat (12, 44.4%) and curved (15, 55.6%) groups based on the contour of MCL map. The MCL and D were lower and shorter in the curved group than the flat group, and CAP score 1 year after surgery and Speech Intelligibility Rating (SIR) 3 years after surgery were better (p < 0.05).

Conclusion: Although abnormal reactions such as facial and vestibular nerve stimulation were observed to be more frequent, lower MCL and better outcomes were observed in relation to the shorter D.

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.

The role of preoperative imaging for auditory implants in children

&lt;b&gt;Introduction:&lt;/b&gt; Preoperative imaging, besides audiological evaluation, plays a major role in evaluation of candidacy for auditory implants, and in particular cochlear implants. It is essential to assess whether the basic criteria necessary for implantation are met. Diagnostic imaging is crucial not only in determining candidacy, but also determining the feasibility of cochlear implantation as it allow to anticipate surgical difficulties which could preclude or complicate the implantation of the device. The aim of the study is to present the protocol for the evaluation of preoperative imaging studies with particular focus on the factors potentially affecting clinical decisions in children qualified for cochlear implantation. &lt;br&gt;&lt;b&gt;Material and method:&lt;/b&gt; Preoperative imaging studies of 111 children performed prior to cochlear implantation were analyzed: high-resolution computed tomography (HRCT) of temporal bones and MRI. The assessment was made according to the presented protocol. &lt;br&gt;&lt;b&gt;Results:&lt;/b&gt; Pathologies and anomalies identified during the assessment of preoperative imaging studies significantly altered clinical decisions in 30% of patients. In the study group, in 17% of patients inner ear malformations were identified. 2.7% of children were disqualified from a cochlear implantation due to severe congenital inner ear malformations. 9% of the patients have had bacterial meningitis. In 50% of them difficulties related to complete or progressive cochlear ossification occurred. In 4.5% of patients less common surgical approaches other than mastoidectomy with a posterior tympanotomy were applied. &lt;br&gt;&lt;b&gt;Discussion:&lt;/b&gt; Preoperative imaging allow for the identification of significant pathologies and anomalies affecting qualification decisions and further treatment. HRCT and MRI are complementary to each other for preoperative imaging. The two modalities in combination allow accurate and optimal evaluation of the anatomical structures prior to implantation. Inner ear malformations and cochlear ossification following meningitis are relatively frequently encountered in children qualified for a cochlear implant.

Electrically evoked ABR during cochlear implantation and postoperative development of speech and hearing abilities in infants with common cavity deformity as a type of inner ear malformation

Background: The electrically evoked auditory brainstem response (eABR) during cochlear implantation in common cavity (CC) deformity has not been clinically well studied.Aim/Objective: To investigate the eABR wave configuration during cochlear implantation, the postoperative development of hearing, and educational settings in infants with CC deformity.Materials and Methods: Nine infants who were congenitally deaf and found to have CC deformity and suspected cochlear nerve deficiency by temporal bone CT and MRI were studied. All of them underwent sequential and unilateral cochlear implantation and their eABRs were recorded during the surgery. The postoperative development was followed up.Results: eABRs of all the nine infants with CC deformity showed that the mean peak of the evoked wave V (eV) was the same as that in controls at latencies but was twofold higher than that in controls at thresholds and their postoperative hearing thresholds improved markedly.Conclusion and Significance: The brainstem auditory pathways of the infants were considered intact on the basis of the eV peak latencies in the eABRs. The postoperative development of their speech and hearing abilities and their educational settings varied, probably because of the twofold higher thresholds of their eABRs and limited number of auditory neural units.

Development of vestibular ocular reflex and gross motor function in infants with common cavity deformity as a type of inner ear malformation

Background： The function of common cavity deformity demonstrated by temporal bone CT and MRI has been unknown.

AIM/OBJECTIVE

To investigate the developmental changes of vestibular ocular reflex and acquisition of postural control in infants with common cavity deformity.

MATERIAL AND METHODS

Eight infants who were congenitally deaf complicated by common cavity deformity were studied. The damped rotational chair test was carried out to evaluate vestibular ocular reflex. Acquisition of head control and independent walking in these infants was compared with that in normal infant's milestones of gross motor development.

RESULTS

All of the eight infants with common cavity deformity did not show per-rotatory nystagmus in the damped rotational chair test around the first year of life. However, a normal number of beats and a longer duration of per-rotatory nystagmus for their age were recorded at around three or four years of age.

CONCLUSIONS AND SIGNIFICANCE

In the eight infants with common cavity deformity, vestibular ocular reflex was not present around the first year of life, but appeared after three or four years probably because of some vestibular sensory cells. Head control and independent walking were delayed but eventually acquired by the central vestibular compensation.

Slotted labyrinthotomy approach with customized electrode for patients with common cavity deformity

OBJECTIVES/HYPOTHESIS

Cochlear implantation for patients with common cavity deformity (CCD) can be difficult, with a higher incidence of intra- and postoperative complications; outcomes with CCD patients are also highly variable. In this study, surgical time was compared between the traditional facial recess approach (TFRA) and the transmastoid slotted labyrinthotomy approach (TSLA). Audiological outcomes and the benefit of using customized electrode arrays for CCD patients are also discussed.

STUDY DESIGN

Retrospective review of 13 cochlear implant (CI) patients with CCD.

METHODS

Six patients were implanted with the TFRA using traditional electrodes, and seven patients were implanted with the TSLA using customized electrodes. Intra- and postoperative complications were reviewed. Audiological outcomes were measured 3 months to 2 years after CI activation.

RESULTS

The mean surgical time for TSLA group was nearly half as long as for the TRFA group (P < .05). Although mean audiological outcomes were better for the TSLA group, there was no significant difference between groups (P > .05).

CONCLUSIONS

For CCD patients, TSLA for cochlear implantation is recommended due to shortened surgical time; customized electrode arrays may be additionally advantageous in terms of audiological outcomes.

LEVEL OF EVIDENCE

4. Laryngoscope, 128:468-472, 2018.

Vestibular evoked myogenic potentials of children with inner ear malformations before and after cochlear implantation

CONCLUSIONS

Our results show that among the patients with inner ear malformations, there were two patients with sensory cells of sacculus and inferior vestibular neurons and at least five patients with inferior vestibular neurons only, but no patients without sensory cells and vestibular neurons, as determined on the basis of vestibular evoked myogenic potentials (VEMPs).

OBJECTIVE

The aim of this study was to investigate whether sensory cells of sacculus or inferior vestibular neurons or both are present in cochlear implant patients with inner ear malformations, particularly common cavity (CC) deformity, using VEMPs.

PATIENTS AND METHODS

Seven children with inner ear malformation who underwent cochlear implantation (CI) participated in this study. The patients had CC deformity (n=2), incomplete partition type I (n=2), incomplete partition type II (n=1), or a narrow internal auditory canal (IAC) (n=2). It was possible to record VEMPs before and after CI in three patients and not before but after CI in four patients. After surgery, VEMPs were recorded with the cochlear implant device switched both off and on.

RESULTS

Before the CI, two patients showed VEMPs and one patient showed no VEMPs, whereas in four patients no VEMPs could be recorded. All the patients showed VEMPs with the cochlear implant on.

Vestibular impairments pre- and post-cochlear implant in children

OBJECTIVES

Determine prevalence and types of vestibular impairments in sensorineural hearing loss (SNHL) in a large population of pediatric candidates for cochlear implants. Evaluate impact of cochlear implants on vestibular function.

STUDY DESIGN

Retrospective and prospective study.

METHODS

Children with profound SNHL (n=224) underwent complete vestibular testing (clinical vestibular examination, bicaloric test, earth vertical axis rotation, off vertical axis rotation and vestibular evoked myogenic potentials) before cochlear implant. Changes in vestibular responses were measured after implants in 89 of these patients.

RESULTS

In the SNHL population only 50% had normal bilateral vestibular function, while 20% had bilateral complete areflexia, 22.5% partial asymmetrical hypoexcitability and 7.5% partial symmetrical hypoexcitability. In the 71/89 follow-up patients showing vestibular responses prior to implant, 51 (71%) had changes in vestibular function including 7 (10%) who acquired ipsilateral areflexia. Others developed ipsilateral hypo- or hyperexcitability. Vestibular modifications occurred during the 3 months after surgery and were not clearly associated with clinical signs except for ipsilateral areflexia cases. In long-term follow-up, two of the 7 patients with ipsilateral areflexia partially recovered vestibular function.

CONCLUSION

Since half of pediatric cochlear implant candidates have vestibular deficits and 51% of implants induce modifications of existing vestibular function, each implant should be preceded by canal and otolith functional tests to assure that the least functional vestibule is implanted. The tests provide baselines for follow-up monitoring of subsequent losses and recovery. This could be easily implemented with a clinical vestibular examination including the head thrust test associated with a bicaloric test and vestibular-evoked-myogenic-potentials.

Surgical Results of Cochlear Implantation in Malformed Cochlea

OBJECTIVE

To report the surgical aspects of cochlear implantation in malformed cochlea.

SETTING

Tertiary care center.

STUDY DESIGN

Retrospective case review.

METHODS

Between November 1997 and October 2004, 20 patients with inner ear malformations were implanted in our department. The age range was between 2 and 37 years (average, 8.8 yr). The anomalies were classified according to Sennaroglu and Saatci classification. There were two patients with common cavity deformity, four cases of incomplete partition (IP) type I (cystic cochleovestibular malformation), four cases of IP type II (classical Mondini's deformity), nine patients with large vestibular aqueduct (LVA) syndrome, and one patient with X-linked deafness.

RESULTS

Standard transmastoid facial recess approach was used in 17 patients (three patients with IP I, four patients with IP II, and nine patients with LVA syndrome). In the remaining patient with IP I, because of the dehiscent and anteriorly located facial nerve, the surgical approach had to be modified, and an anteroposterior approach was used. After elevating the tympanomeatal flap, the electrode was inserted through the ear canal and then transferred to the mastoid through a full-length cut produced in the ear canal. The flap then returned to its place. In the patients with common cavity deformity, the electrode was inserted by the transmastoid labyrinthotomy approach. Facial nerve had an abnormal course in four patients, but no patient had facial weakness postoperatively. Cerebrospinal fluid gusher was encountered in four patients, whereas oozing was present in five patients. It seems that a slightly larger cochleostomy may reduce postoperative rhinorrhea. The patient with common cavity deformity showed abnormal vestibular stimulation which decreased and was totally abolished during a 3-month period.

CONCLUSION

Based on these findings, cochlear implantation is surgically feasible in patients with common cavity, IP types I and II, and LVA. The surgeon should be ready to make modifications in the surgical approach because of the abnormal course of the facial nerve and be ready to produce special precautions to cerebrospinal fluid gusher.

Vestibular-evoked myogenic potentials in cochlear implant children

CONCLUSIONS

Our results suggest that the sacculi of most children with cochlear implants can easily be damaged, as shown by the absence of vestibular-evoked myogenic potentials (VEMPs) in response to click stimuli. Also, in most of the children, the vestibular nerve was seemingly not stimulated by the cochlear implant. These results suggest that electrical stimulation at the C level can stimulate the cochlear nerve; however, this stimulation did not spread to the vestibular nerve in our children. In some children with Mondini dysplasia or vestibulocochlear nerve abnormality, the vestibular nerve was stimulated when the cochlear implant device was on, because of a VEMP response to electrical stimulation.

OBJECTIVE

To clarify the diagnostic value of VEMPs in cochlear implant patients.

MATERIAL AND METHODS

The click-evoked myogenic potentials of 12 children who underwent cochlear implantation surgery were investigated. The latency and amplitude of the VEMP responses were measured.

RESULTS

Before surgery, 6 of the 12 children showed normal VEMPs, 1 showed a decrease in the amplitude of VEMPs and five showed no VEMP response. After surgery, with the cochlear implant device off, 1 child showed a decreased VEMP and 11 showed no VEMPs. With the cochlear implant device on, four children showed VEMPs and eight did not.

Vestibular effects of cochlear implantation

OBJECTIVES/HYPOTHESIS

Cochlear implantation (CI) carries with it the potential risk for vestibular system insult or stimulation with resultant dysfunction. As candidate profiles continue to evolve and with the recent development of bilateral CI, understanding the significance of this risk takes on an increasing importance.

STUDY DESIGN

Between 1997 to 2001, a prospective observational study was carried out in a tertiary care medical center to assess the effects of unilateral CI on the vestibular system.

METHODS

Assessment was performed using the dizziness handicap inventory (DHI), vestibulo-ocular reflex (VOR) testing using both alternate bithermal caloric irrigations (ENG) and rotational chair-generated sinusoidal harmonic accelerations (SHA), and computerized dynamic platform posturography (CDP) at preoperative, 1-month, 4-month, 1-year and 2-year postimplantation visits. CI was carried out without respect to the preoperative vestibular function test results.

RESULTS

Specifically, 86 patients were entered into the study after informed consent. For the group as a whole, pair wise comparisons revealed few significant differences between preoperative and postoperative values for VOR testing (ENG and SHA) at any of the follow-up intervals. Likewise, DHI testing was also unchanged except for significant reductions (improvements) in the emotional subcategory scores at both the 4-month and 1-year intervals. CDP results demonstrated substantial improvements in postural sway in the vestibular conditions (5 and 6) as well as composite scores with the device "off" and "on" at the 1-month, 4-month, 1-year, and 2-year intervals. Device activation appeared to improve postural stability in some conditions. Excluding those patients with preoperative areflexic or hyporeflexic responses in the implanted ear (total [warm + cool] caloric response <or= 15 deg/s), substantial reductions (>or=21 deg/s maximum slow phase velocity) in total caloric response were observed for 8 (29%) patients at the 4-month interval. These persisted throughout the study period. These changes were accompanied by significant low frequency phase changes on SHA testing confirming a VOR insult. Of interest, no significant changes were detected in the DHI or CDP, and there were no effects of age, sex, device manufacturer, or etiology of hearing loss (HL) for these patients.

CONCLUSIONS

Unilateral CI rarely results in significant adverse effects on the vestibular system as measured by the DHI, ENG, SHA, and CDP. On the contrary, patients that underwent CI experienced significant improvements in the objective measures of postural stability as measured by CDP. Device activation in music appeared to have an additional positive effect on postural stability during CDP testing. Although VOR testing demonstrated some decreases in response, patients did not suffer from disabling vestibular effects following CI. The mechanism underlying these findings remains speculative. These findings should be considered in counseling patients about CI.