Static balance function in children with cochlear implants

Objective

This study aimed to assess the static balance function in deaf adolescents with cochlear implants.

Methods

We included 24 adolescents who had received unilateral cochlear implantation for at least 5 years. Each subject underwent stabilometry testing under 4 different conditions: (A) firm surface with eyes open; (B) firm surface with eyes closed; (C) foam pad with eyes open; and (D) foam pad with eyes closed. All of them received tests with their cochlear implant turned on and off. Another 24 age- and sex-matched adolescents with normal hearing were tested in the same way for comparison. Sway velocity and circular area were measured and analyzed.

Results

The mean sway velocity of the cochlear implant group under conditions A-D was 1.68, 1.98, 2.36, and 5.25 cm/s, respectively, and the mean circular area of the cochlear implant group under conditions A-D was 7.39, 6.68, 12.21, and 34.27 cm², respectively. Both of the parameters showed statistical significance between the cochlear implant group and the normal hearing group for conditions A, C and D (p < 0.05). Furthermore, there was no significant balance function change among cochlear implant group with their implant “on” and “off”.

Conclusions

This study showed that the static balance function in adolescents with long-term use of cochlear implants was worse than those of normal hearing peers. The difference between the cochlear implant group and normal hearing group was the highest when both visual and somatosensory inputs were disrupted. The postural stability was similar whether or not the cochlear implant was activated.     

Effects of cochlear implants on otolith function as evaluated by vestibulo-ocular reflex and vestibular evoked myogenic potentials

ObjectiveThe aim of this study was to investigate whether the insertion of an implant into the cochlea is accompanied by a deterioration in otolith function. Cervical and ocular vestibular evoked myogenic potentials (cVEMP and oVEMP) and linear vestibulo-ocular reflex (lVOR) during eccentric rotation were assessed before and after cochlear implantation (CI) to evaluate otolith function.MethodsTwelve patients with bilateral severe sensorineural hearing loss who had undergone CI surgery in our hospital between May 2016 and November 2017 were included in this study. cVEMP and oVEMP were assessed using the asymmetry ratio (AR), calculated with the following formula: [(peak-to-peak amplitude calculated as the sum of the p13 and n23 amplitudes in the non-operated side) − (that in the operated side)]/[(that in the non-operated side) + (that in the operated side)]. The ratio of VOR gain during eccentric rotation against VOR gain during center rotation was used to assess lVOR. For eccentric rotation, patients were rotated while displaced from the axis of rotation. At the same time, linear acceleration stimulated the utricle and induced lVOR. All patients underwent cVEMP and oVEMP tests and center and eccentric rotation tests before and about 30 days after CI surgery.ResultsThree patients with absent cVEMP responses before surgery were excluded, leaving pre-surgery cVEMP results for 9/12 patients. In five of these patients, the AR of cVEMP increased after CI, indicating that saccular function, as evaluated by cVEMP, did not deteriorate significantly postoperatively. One patient with an absent oVEMP response before CI was excluded, leaving pre-surgery oVEMP results for 11/12 patients. In 10 of these patients, the AR of oVEMP increased after CI surgery, indicating that utricular function, as evaluated by oVEMP, deteriorated significantly postoperatively. However, because the ratio of VOR gain during eccentric rotation against VOR gain during center rotation did not become worse after CI, utricular function, as evaluated by lVOR, did not deteriorate significantly postoperatively. Symptoms of vertigo became worse after CI in two of the 12 patients.ConclusionCI does not cause a deterioration in saccular function, as evaluated by cVEMP. Although CI does cause a deterioration in utricular function in oVEMP tests, this is not consistent in lVOR tests. These results indicate that CI causes a slight deterioration in utricular function that is insufficient to cause vertigo or deterioration of lVOR.     

人工耳蜗植入术后患者前庭诱发肌源性电位的研究

目的探讨人工耳蜗植入术对患者前庭功能的影响。方法本研究入选对象为2001年至2009年由同一术者行人工耳蜗植入手术,且均为术后6个月以上年龄大于6岁的患者。排除1例非前庭因素自行放弃使用人工耳蜗者,共有12例患者参与本研究。应用前庭诱发肌源性电位（vestibular evoked myogenic potential,VEMP）检查进行前庭功能检测,以p13、n23波潜伏期与振幅作为评定指标。结果12例患者双侧短声刺激p13波和n23波出现率为50%（6/12）。诱发出波形的手术耳组p13潜伏期与非手术耳组相比,两者无显著性差异（P＞0.05）。手术耳组n23潜伏期与非手术耳组相比,两者无显著性差异（P＞0.05）。|p13-n23|手术耳组与非手术耳组相比,两者无显著性差异（t=0.009,P＞0.05）。手术耳组振幅低于非手术耳组振幅,差异具有统计学意义（t=3.75,P<0.05）。结论人工耳蜗植入术对VEMP的传导并无影响,但可造成手术耳VEMP振幅下降,可能与人工耳蜗植入术的手术刺激或长期的电极植入对球囊功能的影响有关。     

Vestibular functions in motion sickness susceptible individuals

There exists no functional guide that can serve as a diagnostic tool for individual susceptibility to motion sickness (MS). We evaluated vestibular system functioning via a caloric test (which assesses functioning of the superior vestibular nerve) and the vestibular-evoked myogenic potentials (VEMP) test (which assesses inferior vestibular nerve functioning) in 20 MS susceptible and 20 nonsusceptible individuals. Susceptibility to MS was determined by self-declaration and with MS susceptibility questionnaire and Hamilton Anxiety Scale (HAS). We found statistically significant differences for scores on the MS susceptibility questionnaire and HAS questionnaire; however, we found no correlation between VEMP and caloric test results. We suggest that VEMP and caloric test results are not affected by individuals’ susceptibility to MS. We could not find vestibular system deficits using the VEMP and caloric test combination. Our findings do not support vestibular function asymmetry in MS patients.     

Vestibular evoked myogenic potentials in children after cochlear implantation

Objective

The aim of this study was to report the effect of unilateral cochlear implantation to vestibular system using vestibular evoked myogenic potentials (VEMPs) by air-conduction in a sample of children aged less than 5 years.

Materials

This study consisted of 10 children (6 boys and 4 girls), who underwent cochlear implantation surgery at our clinic, and 8 normal hearing children (5 boys and 3 girls) matched for age. The VEMPs were performed before, 10 days, and 6 months after surgery. Both the implanted and unimplanted ears of each child were evaluated, with the cochlear implant both off and on.

Results

Preoperatively, six (60%) children had abnormal VEMPs responses on both ears. In the postoperative sessions, no child showed any VEMPs response on the implanted side. The VEMPs were not recorded on the unimplanted side either, except for one case. At 6 months, the VEMPs response on the unimplanted side of three children became normal when the cochlear implant was on, and in two children with the device off.

Conclusion

In the postoperative 6-month-period, the disappearance of VEMPs suggests that the saccule of children can be extensively damaged following cochlear implantation. A recovery of VEMPs can take place on the unimplanted side, with the cochlear implant both on and off. Despite this saccular injury, the absence of clinical signs in children could be explained by their ability to effectively compensate for such vestibular deficits.     

Different forms of dizziness occurring after cochlear implant

Dizziness after cochlear implant (CI) was studied in a series of 94 consecutive adult patients receiving a cochlear implant, 46 (49.0%) of whom experienced dizziness post-operatively. In 29 patients, post-operative dizziness occurred soon after surgery and subsided within one month. Dizziness of the continuous type, lasting more than 6 months, was a complaint in only two patients. In addition to these already known forms of dizziness, spells of vertigo occurring later than one month after cochlear implant were experienced by 15 patients (delayed-V). The spells of delayed-V occurred suddenly and persisted for several hours. Moreover, 85.7% of delayed-V patients complained of hearing and tinnitus abnormalities during these spells. The clinical features of delayed-V were similar to those in patients with Ménière’s disease. The preoperative bithermal caloric test showed a significantly higher response for the delayed-V group than the other groups (ANOVA: P < 0.05) in terms of slow phase eye velocity of caloric nystagmus. These findings suggest that inner ear lesions due to cochlear implant surgery develop gradually. Similarities in clinical features between delayed-V and Ménière’s disease indicate the presence of labyrinthine hydrops. Received: 28 March 2000 / Accepted: 12 October 2000     

Supporting cell survival after cochlear implant surgery

Supporting cells (SCs) provide structure and maintain an environment that allows hair cells to receive and transmit signals in the auditory pathway. After insult to hair cells and ganglion cells, SCs respond by marking unsalvageable cells for death and maintain structural integrity. Although the histopathology after cochlear implantation has been described regarding hair cells and neural structures, surviving SCs in the implanted ear have not. We present a patient whose posthumous examination of an implanted cochlea demonstrated SC survival. This finding has implications for SC function in maintaining electrical hearing and candidacy for future hair cell regeneration therapies. Laryngoscope, 129:E36–E40, 2019     

Facial nerve paralysis following cochlear implant surgery

OBJECTIVES: Facial nerve paralysis is a rare but devastating complication of cochlear implant surgery. The aims of the study were to define the incidence of facial nerve paralysis in our series and understand possible mechanisms of injury. STUDY DESIGN: Retrospective chart review and case reports. METHODS: Charts were reviewed of all 705 patients implanted between 1980 and 2002 at the authors' institutions to identify those with postoperative facial nerve weakness and determine incidence. For patients with facial nerve weakness, onset, degree, and timing of paralysis were noted; clinical findings were correlated to operative report findings. The method of treatment was noted, and the final facial nerve function outcome was recorded. RESULTS: Five patients (one child and four adults) were found to have postoperative facial nerve weakness, for an incidence of 0.71%. This complication was delayed in all cases, ranging from 18 hours to 19 days postoperatively. All patients were treated with steroids or steroids combined with antiviral medication, and all ultimately recovered normal facial function. CONCLUSIONS: In the study series, the incidence of facial nerve paralysis following cochlear implant surgery was 0.71%. Possible mechanisms of injury included heating injury and viral reactivation. All patients presented with a delayed facial nerve paralysis and did recover normal facial nerve function.     

Antibiotic prophylaxis in cochlear implant surgery

OBJECTIVES/HYPOTHESIS: We conducted this study to determine the incidence of infection in cochlear implant surgery after using perioperative antibiotics. STUDY DESIGN: Study design was a retrospective case series. METHODS: There was a retrospective chart review of 95 patients (81 adults, 14 children) undergoing 98 cochlear implants. RESULTS: The incidence of infection following cochlear implant surgery was 1% with the use of perioperative antibiotics. CONCLUSIONS: Perioperative antibiotics, usually administered as a single dose, are sufficient for the prevention of major wound infection after cochlear implant surgery.     

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.     

Feasibility of one-day activation in cochlear implant recipients

Objective: To determine if cochlear implants recipients can be safely and effectively fitted with their sound processor one day after their implant surgery. Design: All subjects were implanted with MED-EL Concerto cochlear implant. Subjects’ electrode impedance levels, maximum comfortable levels, and threshold levels were measured one day after surgery and compared to measurements obtained one month post implantation using the non-parametric Wilcoxon signed-rank test. Study sample: Twenty-nine participants in the age range of 1 to 42 years (average of 5 years). Results: No adverse events were reported post-operatively. Measures after one day of surgery were significantly less than those measured one month post implantation. Conclusion: Early activation of the implant did not impact the healing process of the incision site, suggesting that one-day activation of the implant is feasible for some patients when medically possible. The evolution of the impedance and stimulation levels were consistent with that reported in previous studies, which indicates that early activation did not interfere with the physiological changes taking place after implantation.     

Computer modelling of the cochlea and the cochlear implant: A review

Abstract

In the last few decades, cochlear implants have experienced major developments with intensive studies carried out through experimental and computational analysis. With the rapid increase in computational resources available and the development of efficient computational techniques, computer models of the cochlea and the cochlear implant have become more sophisticated. It is now possible to analyze the micromechanics of the cochlea and the transient response of tissue to external stimulation. This study reviews the major developments in cochlear models, summarizes, and categorizes features of models used in different studies and makes recommendations for future development. The paper is classified into four sections detailing features of the cochlear models, electrodes, electrical stimulation, and software used in different studies. The paper highlights unexplored areas in the model design and suggests additions to develop a better computer model.     

Long-term results of hearing preservation cochlear implant surgery in patients with residual low frequency hearing

Conclusion: Differences were found between patients with stable hearing and those with progressive hearing loss in the lower frequencies with respect to the rate of progression in the contralateral ear. It is suggested that the electric acoustic stimulation (EAS) can provide improvement in hearing ability over the long-term if residual hearing might be lost to some extent.

Objective: To evaluate the long-term threshold changes in the low frequency hearing of the implanted ear as compared with the non-implanted ear, and the hearing abilities with EAS along with the extent of residual hearing.

Methods: Seventeen individuals were enrolled and received the EAS implant with a 24-mm FLEXeas electrode array. Hearing thresholds and speech perception were measured pre- and post-operatively for 1–5 years. Post-operative hearing preservation (HP) rates were calculated using the preservation numerical scale.

Results: The average linear regression coefficient for the decline in hearing preservation score was ?6.9 for the implanted ear and the patients were subsequently categorized into two groups: those with better than average, stable hearing; and those with worse than average, progressive hearing loss. EAS showed better results than electric stimulation alone, in spite of an absence of speech perception with acoustic stimulation.     

Intracochlear assessment of electrode position after cochlear implant surgery by means of multislice computer tomography

The development of electrode arrays, the past years, has focused on modiolus-hugging cochlear implant electrodes. Besides, atraumatic implantation of electrodes is of importance for the use in hearing preservation, in cases of combined electric and acoustic stimulation. Intracochlear positioning of the individual electrodes by means of multislice computer tomography (CT) has not yet been shown. In this study we formulated and tested a CT imaging protocol for postoperative scanning of the temporal bone in cochlear implant subjects. Both a fresh human temporal bone and a fresh human cadaver head were implanted with a cochlear implant. Multislice CT was performed for adequate depiction of the cochlear implant. All scans were analyzed on a viewing workstation. After mid-modiolar reconstruction we were able to identify the intracochlear electrode position relative to the scala tympani and scala vestibuli. This was possible in both the implanted isolated temporal bone and the fresh human cadaver head. The feasibility of imaging the electrode position of the cochlear implant within the intracochlear spaces is shown with multislice CT. An imaging protocol is suggested.     

A high rate n-of-m speech processing strategy for the first generation Clarion cochlear implant

Abstract

An n-of-m speech coding strategy has been developed for the Clarion Cochlear Implant Series 1.x (1.0 & 1.2). The basic principle is to reduce the number of stimuli per cycle, by neglecting the less significant spectral components, and to concentrate on the more dominant frequency bands. In this study 20 subjects, implanted with a Clarion device, used an n-of-m strategy at 1666 pps per channel. The outcomes using this strategy were compared with the outcomes using conventional processing (CIS at 833 pps/channel). Eight of the 20 subjects underwent additional testing with the n-of-m strategy with the rate set at 833 pps/channel. Using the n-of-m strategy at 1666 pps showed statistically significant improvement in performance over the CIS strategy, with 16 of the 20 subjects achieving better results. However, there was no statistically meaningful difference in performance between n-of-m at 833 pps and the CIS strategy running at the same rate. Results therefore suggest that n-of-m strategy can be an alternative to CIS, particularly when the implant hardware limits the overall stimulation rate.

Sumario

Se ha desarrollado una estrategia n-of-m de codificación del lenguaje para el implante coclear Clarion en sus series 1 × (1.0 & 1.2). El principio básico es reducir el número de estímulos por ciclo, abandonando los componentes espectrales menos significativos y concentrándose en las bandas de frecuencia más dominantes. En este estudio 20 sujetos implantados con un Clarion, usaron una estrategia n-of-m a 1666 pps por canal. Los resultados con el uso de esta estrategia se compararon con los obtenidos al usar procesamiento convencional (CIS a 833 pps/ canal).Ocho de los 20 sujetos realizaron pruebas adicionales con la estrategia n-of-m a una tasa de 833 pps/canal. El uso de la estrategia n-of-m a 1666 pps mostró una mejoría estadísticamente significativa en el rendimiento, en comparación con la estrategia CIS, en 16 de los 20 sujetos que obtuvieron mejores resultados. No obstante, no hubo una diferencia estadísticamente significativa en el rendimiento entre la condición de 833 pps y la estrategia CIS, practicadas a la misma tasa. Los resultados sugieren por consiguiente que la estrategia n-of-m puede ser una alternativa de la CIS, particularmente cuando el equipo limita la tasa total de estimulación.     

The effect of cochlear implants on vestibular-evoked myogenic potential responses and postural stability

Objective

Current spread by electrical stimulation via inserted cochlear implant (CI) electrodes and the consequential increase in sound input can affect the equilibrium of patients. The aim of the present study was to clarify the effect of CIs on the equilibrium of patients through cervical vestibular-evoked myogenic potential (cVEMP) testing and static stabilometry performed with the CIs turned on (CI-on) and off (CI-off).