Cochlear implantation in patients with neurofibromatosis type 2 and patients with vestibular schwannoma in the only hearing ear

Efficacy of Cochlear Implantation in Neurofibromatosis Type 2 Related Hearing Loss

OBJECTIVE

To investigate the results of cochlear implantation in subjects with neurofibromatosis type 2 (NF2) and bilateral vestibular schwannomas (VS).

STUDY DESIGN

Retrospective case series.

SETTING

University-based tertiary referral center.

SUBJECTS

Five subjects with NF2 and severe-to-profound sensorineural hearing loss.

INTERVENTION

Cochlear implantation.

MAIN OUTCOME MEASURE

Surgical outcomes and audiometric performance after cochlear implantation.

RESULTS

Five subjects (3 female, 2 male) were included in the study. The mean age at the time of implantation was 54 years old (range 35-78 years). Follow-up after cochlear implantation averaged 38 months (range 21-106 months). In the 5 implanted ears, 2 had no prior treatment, 1 had undergone prior radiation therapy, 1 underwent prior microsurgical removal, and 1 underwent prior microsurgical removal with adjuvant radiation therapy. The mean ipsilateral VS dimensions at time of implantation were 14 mm × 7.2 mm × 6.1 mm (mediolateral × anteroposterior × craniocaudal). Following cochlear implant activation, all 5 subjects achieved sound awareness, open set speech recognition, and 4 continue to be daily users of the devices.

CONCLUSION

Cochlear implantation is a viable hearing rehabilitation option for subjects with NF2 and severe-to-profound sensorineural hearing loss. All subjects reported benefit with their cochlear implant, including open set speech recognition, enhanced lip-reading skills and environmental awareness of sound. Four subjects continued to demonstrate improved open-set speech recognition at the time of their last evaluations.

Diagnostic Accuracy of Intracochlear Test Electrode for Acoustic Nerve Monitoring in Vestibular Schwannoma Surgery

OBJECTIVES

Cochlear implants (CIs) are a well-known hearing restoration option for patients with vestibular schwannoma (VS) in cases of neurofibromatosis type-2 and, more recently, for patients with sporadic VS. One of the main limitations when performing CI during VS surgery is the capability to preserve the acoustic nerve (AN) anatomically and functionally. Significant efforts have been directed toward developing an intraoperative testing method for monitoring the AN function to determine if, after tumor removal, it is suitable for conducting stimuli delivered by a CI. However, all these methods have significant limitations, and none of them have documented diagnostic efficacy. To overcome these limitations and to obtain reliable information before CI insertion, a minimally invasive intracochlear test electrode (TE) has been recently developed. This TE has demonstrated to be suitable to test the integrity of the AN before CI in patients without any residual hearing by recording electrically evoked auditory brainstem responses (EABR). The present study constitutes the next phase of this research, which was to determine the usefulness of EABR obtained intraoperatively with the intracochlear TE after the resection of a VS and to calculate its diagnostic accuracy to assess the functionality of the AN for CI.

DESIGN

This was a prospective, multicenter study of diagnostic accuracy. It was conducted in three tertiary referral centers between January 2015 and 2018. This study was designed following the Standards for Reporting of Diagnostic Accuracy Studies (STARD) statement guidelines. The STARD statement are guidelines to improve the completeness and transparency of reports of diagnostic accuracy studies. The diagnostic accuracy of the EABR evoked with the intracochlear TE after tumor removal was studied. Accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were calculated. Patients eligible for the study were consecutive adults undergoing surgery for VS with simultaneous CI. The test under evaluation (index test) was the EABR obtained with the intracochlear TE after resection of the tumor. The reference test (gold standard) was the presence of auditory perception with the CI, defined as the presence of sound detection on an audiogram at 500, 1000, 2000, and 4000 Hz of no greater than 50 dB. In all the cases, auditory perception was verified by the presence of a positive EABR evoked with the CI.

RESULTS

Twenty-one patients were included during the study period; seven patients were excluded from the diagnostic efficacy analysis due to inconclusive EABR results or absence of the gold standard to compare (they did not finally receive the CI). Thus, the outcome of the gold standard was assessed in 14 cases: 9 cases had positive EABR, all of them obtained auditory perception with the CI, and 5 cases had negative EABR, only one case had auditory perception with the CI, which constitutes the only false negative of this study. Accuracy of the TE was 93% (95% confidence interval, 66 to 100%), sensitivity 90% (95% confidence interval, 71 to 100%), specificity 100% (95% confidence interval, 100 to 100%), positive predictive value 100% (95% confidence interval, 100 to 100%), and negative predictive value 80% (95% confidence interval, 45 to 100%).

CONCLUSIONS

EABR elicited with the intracochlear TE had a diagnostic accuracy of 93% for predicting auditory perception with CIs after VS removal. These results suggest that the intracochlear TE can be used intraoperatively after tumor removal to test the integrity of the AN as a useful tool to complement the surgeon's perception for decision-making regarding implantation.

The emerging role of hearing loss rehabilitation in patients with vestibular schwannoma treated with Gamma Knife radiosurgery: literature review

Stereotactic radiosurgery (SRS) is currently the most common treatment for small- to medium-size vestibular schwannoma (VS). Despite favorable outcome, hearing deterioration still remains an underestimated problem, and the role of hearing rehabilitation is an underinvestigated topic. Among available technologies, cochlear implant (CI) should represent a valid alternative in sporadic VS with single-sided deafness and in neurofibromatosis (NF2) with bilateral profound hearing loss. A literature review of the current clinical data was performed searching scientific literature databases. From all of the articles found, 16 papers were selected. Forty-four subjects treated with radiosurgery (18 male, 19 female, and in 7 cases, sex were not specified; 43 NF2 and 1 sporadic VS) were included in the analysis. Epidemiological, clinical, tumor, treatment, and audiological data were collected. Clinical outcome at last follow-up showed an audiological improvement in 25 of the 44 patients. The audiological outcome was unchanged in 16 cases. Audiological deterioration was recorded in 3 cases. Severity of NF2 phenotype, long history of ipsilateral profound deafness before implantation, progressive tumor growth, and high radiation dose (20 and 40 Gy) were found in patients with a worst audiological outcome. Hearing rehabilitation can improve audiological results for VS patients following SRS in selected cases. Hearing rehabilitation with cochlear implant (CI) in SSD leads to partial restoration of binaural hearing with an improvement in speech comprehension in noise and in sound localization, and partial suppression of subjective incapacitating tinnitus. SRS followed by CI may represent in selected cases a potential emerging option in the management of these patients, aimed at improving their quality of life. Possible implications for the follow-up of these patients are still present, although partially resolved.

Outcomes of cochlear implantation in patients with neurofibromatosis type 2

In neurofibromatosis type 2 (NF2) bilateral vestibular schwannomas (VS) or their treatment usually results in bilateral hearing loss. Cochlear implantation (CI) was traditionally not used in these patients due to concern that retrocochlear disease would render the implant ineffective. This paper describes the auditory outcomes of CI in 13 patients with NF2 and includes patients with untreated VS and patients undergoing VS removal with cochlear nerve preservation. The non-user rate was 7.7%. Of the active users, median CUNY score was 98%, median BKB score in quiet was 90% and median BKB score in noise was 68%. CI is a viable option in selected patients with NF2.

Stereotactic radiosurgery does not appear to impact cochlear implant performance in patients with neurofibromatosis type II

INTRODUCTION

Neurofibromatosis Type 2 (NF2) is a genetic condition associated with the presence of bilateral vestibular schwannoma and progressive sensorineural hearing loss. Treatment options include observation, stereotactic radiosurgery (SRS) or surgical resection. Historically, retrocochlear pathology was a contraindication to cochlear implantation (CI). However it is now recognized as viable, in an attempt to restore hearing and improve communication.Thus, the aim of this study was to contrast auditory function in CI recipients with NF2 whose tumors were either observed versus initially treated with SRS.

METHODS

A local review of hearing outcomes in 2 CI patients (3 ears total) with NF2 was undertaken and then pooled with the existing medical literature. Comparative post-implant outcome data, including pure-tone average and aided speech perception measurements was analyzed and compared between 8 subjects whose tumors were observed and 11 subjects who received pre-implantation SRS.

RESULTS

Mean tumor size in the observation cohort was 0.81cm (.13cm to 1.50cm), and 2.34cm in the SRS group (0.10cm to 3.7cm). The mean reported duration of deafness was 22 months as compared to 71 months in the SRS cohort. Both groups demonstrated similar pre-implant candidacy criteria, average age and open-set speech recognition. Although disparate outcome measurements were utilized across studies, an analysis of post-implant open-set speech perception found no significant differences between groups.

CONCLUSION

Despite a small sample size and highly variable post implantation testing methods, patients who undergo SRS for NF2 associated Schwannoma prior to CI have similar hearing performance and benefit by having already completed definitive tumor management.

Vestibular Schwannoma Resection with Ipsilateral Simultaneous Cochlear Implantation in Patients with Normal Contralateral Hearing

Objective: To report the hearing results of cochlear implantation simultaneous to vestibular schwannoma (VS) resection by means of a translabyrinthine approach in patients with normal contralateral hearing. Methods: This was a prospective study including adults with sporadic VS. Tumors were resected by means of a modified translabyrinthine approach with preservation of the cochlear nerve. Results: A total of 13 patients underwent cochlear implantation. At 14 months, the mean pure-tone audiogram was 56 dB. The mean speech recognition was 80%. Cochlear implantation provides monaural and binaural benefits in all the conditions tested, including sound localization. Conclusions: Cochlear implantation can be safely performed simultaneously to VS resection with satisfactory hearing results provided that the cochlear nerve is anatomically intact.

Hearing Restoration in Neurofibromatosis Type II Patients

Patients with neurofibromatosis type II will eventually succumb to bilateral deafness. For patients with hearing loss, modern medical science technology can provide efficient hearing restoration through a number of various methods. In this article, several hearing restoration methods for patients with neurofibromatosis type II are introduced.

Hearing Outcomes After Stereotactic Radiosurgery for Vestibular Schwannomas : Mechanism of Hearing Loss and How to Preserve Hearing

The use of stereotactic radiosurgery (SRS) expanded to include the treatment of vestibular schwannomas (VSs) in 1969; since then, efforts to increase tumour control and to reduce cranial neuropathy have continued. Using the currently recommended marginal dose of 12-13 Gy, long-term reported outcomes after SRS include not only excellent tumour control rates of 92-100 % but also outstanding functional preservation of the trigeminal and facial nerves, with values of 92-100 % and 94-100 %, respectively. Nonetheless, hearing preservation remains in the range of 32-81 %. Previous studies have suggested possible prognostic factors of hearing preservation such as the Gardner-Robertson grade, radiation dose to the cochlea, transient volume expansion (TVE) after SRS, length of irradiated cochlear nerve, marginal dose to the tumour, and age. However, we still do not clearly understand why patients lose their hearing after SRS for VS.Relevant to these considerations, one study recently reported that the auditory brainstem response (ABR) wave V latency and waves I and V interval (IL_I-V) correlated well with intracanalicular pressure values and even with hearing level. The demonstration that ABR values, especially wave V latency and IL_I-V, correlate well with intracanalicular pressure suggests that patients with previously elevated intracanalicular pressure might have an increased chance of hearing loss on development of TVE, which has been recognised as a common phenomenon after SRS or stereotactic radiotherapy (SRT) for intracranial schwannomas.In our experience, the ABR IL_I-V increased during the first 12 months after SRS for VSs in patients who lost their serviceable hearing. The effect of increased ABR IL_I-V on hearing outcome also became significant over time, especially at 12 months after SRS, and was more prominent in patients with poor initial pure-tone average (PTA) and/or ABR values. We hypothesise that patients with considerable intracanalicular pressure at the time of SRS are prone to lose their serviceable hearing due to the added intracanalicular pressure induced by TVE, which usually occurs within the first 12 months after SRS for VSs. Using these findings, we suggested a classification system for the prediction of hearing outcomes after SRS for VSs. This classification system could be useful in the proper selection of management modalities for hearing preservation, especially in patients with only hearing ear schwannoma or neurofibromatosis type 2.Advances in diagnostic tools, treatment modalities, and optimisation of radiosurgical dose have improved clinical outcomes, including tumour control and cranial neuropathies, in patients with VSs. However, the preservation of hearing function still falls short of our expectation. A prediction model for hearing preservation after each treatment modality will guide the proper selection of treatment modalities and permit the appropriate timing of active treatment, which will lead to the preservation of hearing function in patients with VSs.

Ipsilateral cochlear implantation in patients with sporadic vestibular schwannoma in the only or best hearing ear and in patients with NF2

The aim of this study was to evaluate the cochlear implant (CI) performances in neurofibromatosis type 2 (NF2) patients with bilateral vestibular schwannoma (VS) and in patients with sporadic VS in the only or better hearing ear. All patients with bilateral VS or sporadic VS in the only or better hearing ear who underwent cochlear implantation, either simultaneous to VS surgery or staged after treatment for VS, in the tumor side were chosen for the study. Postimplantation audiometric scores (sound detection, closed-set and open-set discrimination scores) and device use patterns were the main outcome measures. 15 patients were implanted. Eight patients (53 %) were NF2 and seven patients had VS in the only or better hearing ear. One patient was explanted for cerebrospinal fluid leak. In the CI-only condition, the other 14 patients obtained sound detection, 64 % of them achieving open-set discrimination (mean 70 ± 38 %) and 85 % achieving closed-set discrimination (mean 41 ± 33 %). At the last follow-up 10 patients (67 %) were using the CI. Cochlear implantation provides hearing in particular cases of patients with bilateral VS or VS in the only or better hearing ear. As long as anatomic preservation of the cochlear nerve is achieved, cochlear implantation may offer improvement in communication skills for most patients.

English consensus protocol evaluating candidacy for auditory brainstem and cochlear implantation in neurofibromatosis type 2

OBJECTIVE

Hearing loss resulting from bilateral vestibular schwannomas (VSs) has a significant effect on the quality of life of patients with neurofibromatosis Type 2 (NF2). A national consensus protocol was produced in England as a guide for cochlear implantation (CI) and auditory brainstem implantation (ABI) in these patients.

STUDY DESIGN

Consensus statement.

SETTING

English NF2 Service.

PARTICIPANTS

Clinicians from all 4 lead NF2 units in England.

MAIN OUTCOME MEASURES

A protocol for the assessment, insertion and rehabilitation of CI and ABI in NF2 patients.

RESULTS

Patients should undergo more detailed hearing assessment once their maximum aided speech discrimination score falls below 50% in the better hearing ear. Bamford-Kowal-Bench sentence testing scores below 50% should trigger assessment for auditory implantation, as recommended by the National Institute for Clinical Excellence guidelines on CI. Where this occurs in patients with bilateral stable VS or a unilateral stable VS where the contralateral cochlear nerve was lost at previous surgery, CI should be considered. Where VS surgery is planned, CI should be considered where cochlear nerve preservation is thought possible, otherwise an ABI should be considered. Intraoperative testing using electrically evoked auditory brainstem responses or cochlear nerve action potentials may be used to determine whether a CI or ABI is inserted.

CONCLUSION

The NF2 centers in England agreed on this protocol. Multisite, prospective assessments of standardized protocols for auditory implantation in NF2 provide an essential model for evaluating candidacy and outcomes in this challenging patient population.

Hearing restoration in NF2 patients and patients with vestibular schwannoma in the only hearing ear: report of two cases

OBJECTIVE

To explore audiologic outcome of auditory brain stem implantation (ABI) and cochlear implantation (CI) in NF2 patients and patients with vestibular schwannoma (VS) in the only hearing ear.

PATIENTS AND METHODS

Study includes retrospective analysis of 2 cases. One is totally deaf patient due to NF2, and the other one is totally deaf due to VS development in only hearing ear. Tumor was removed by retrosigmoid approach in NF2 patient and ABI was performed simultaneously. For the VS in only hearing ear case, tumor was removed by translabyrinthine approach and CI was performed simultaneously.

RESULTS

ABI patient showed quite well outcome during the 15 months of follow-up. She has 25 dB hearing threshold at speaking frequencies. She developed open set speech discrimination with 87.5% word discrimination score, and 70% sentence discrimination score. She uses device daily manner, she can use telephone. For CI patient, outcome is not perfect but satisfactory. She couldn't develop open set speech discrimination during the 18 months of follow-up. She has 67% the disyllabic words recognition score (close set). She is daily user of device. CI improves quite well lip reading.

CONCLUSION

ABI and CI are the two options to restore hearing in VS caused deafness. We advocate giving every effort to preserve cochlear nerve during the VS resection and place CI simultaneously. However if it is not possible to preserve cochlear nerve during surgery, ABI is also a good alternative for hearing restoration.

Retrolabyrinthine approach for cochlear nerve preservation in neurofibromatosis type 2 and simultaneous cochlear implantation

Introduction: Few cases of cochlear implantation (CI) in neurofibromatosis type 2 (NF2) patients had been reported in the literature. The approaches described were translabyrinthine, retrosigmoid or middle cranial fossa.

Objectives: To describe a case of a NF2- deafened-patient who underwent to vestibular schwannoma resection via RLA with cochlear nerve preservation and CI through the round window, at the same surgical time.

Resumed Report: A 36-year-old woman with severe bilateral hearing loss due to NF2 was submitted to vestibular schwannoma resection and simultaneous CI. Functional assessment of cochlear nerve was performed by electrical promontory stimulation. Complete tumor removal was accomplishment via RLA with anatomic and functional cochlear and facial nerve preservation. Cochlear electrode array was partially inserted via round window. Sound field hearing threshold improvement was achieved. Mean tonal threshold was 46.2 dB HL. The patient could only detect environmental sounds and human voice but cannot discriminate vowels, words nor do sentences at 2 years of follow-up.

Conclusion: Cochlear implantation is a feasible auditory restoration option in NF2 when cochlear anatomic and functional nerve preservation is achieved. The RLA is adequate for this purpose and features as an option for hearing preservation in NF2 patients.