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

Cochlear Implantation in Neurofibromatosis Type 2-Related Schwannomatosis: Long-Term Hearing Outcomes

OBJECTIVE

To evaluate long-term hearing outcomes following cochlear implantation in patients with neurofibromatosis type 2 and ipsilateral vestibular schwannoma.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary general hospital.

METHODS

Twenty-two patients undergoing cochlear implantation between 2004 and 2018 with at least 1 year of follow-up were included. Patients were categorized as "users" or "nonusers" of their cochlear implant (CI). For users, speech perception (disyllabic words) without lip-reading was assessed in quiet conditions 1-year postimplantation, and annually thereafter. CI users were classified into 2 groups on the basis of speech intelligibility (≥40% or <40%). Demographic data, treatment options, and tumor size were also recorded.

RESULTS

One year after implantation, 16 (73%) patients used their CI daily. Twelve of these patients had a speech intelligibility ≥40% (mean: 74 ± 21.9%). Three had a Koos stage IV tumor. At the last visit (mean duration of follow-up: 6 ± 5 years), 12 of these 16 patients were still using their implant daily, and 6 had a speech intelligibility ≥40%. No predictive factors for good performance at 1 year or performance stability were identified.

CONCLUSION

Neurofibromatosis type 2 is a complex disease profoundly affecting patient quality of life, and cochlear implantation should always be considered on a case-by-case basis. In some individuals, cochlear implantation can provide good speech intelligibility for extended periods, even posttreatment or in cases of large tumors.

Stereotactic Radiosurgery and Radiotherapy for Vestibular Schwannoma in NF2-Related Schwannomatosis

OBJECTIVES

To determine the long-term control rates and hearing outcomes for growing vestibular schwannoma in NF2-related schwannomatosis (NF2) treated with stereotactic radiosurgery (SRS) and fractionated radiotherapy (FRT).

METHODS

Retrospective review of all patients treated with SRS/FRT between 1986 and2021 from a tertiary NF2 unit. Overall tumor control was defined as: (1) growth control (growth failure was defined as growth in any dimension of 3 millimetres or more from baseline post-SRS/FRT), and (2) treatment control (no need for further intervention). Loss of serviceable hearing was defined as a drop in speech discrimination score below 50% after SRS/FRT.

RESULTS

There were 81 cases, with a mean duration of follow-up of 125 months. Overall control rate was 72% (58/81), with 80% (65/81) growth control and 74% (60/81) treatment control. There was a 5-year actuarial survival of 77% and 10-year survival of 71%. Forty-three percent (30/69) of cases did not have serviceable hearing at baseline. Of those remaining, 49% (19/39) preserved serviceable hearing during follow-up at a mean of 106 months. Actuarial survival for preservation of serviceable hearing at 5 and 10 years was 69% and 53%. There were poorer outcomes with increasing genetic severity, and with baseline tumor size >3 cm. No cases of SRS/FRT-related malignancy were identified at a mean follow-up of 10 years.

CONCLUSION

Stereotactic radiosurgery/fractionated radiotherapy are an effective option to treat growing vestibular schwannoma in patients with NF2 with the potential for hearing preservation in a proportion of patients.

LEVEL OF EVIDENCE

4-Case Series Laryngoscope, 134:2364-2371, 2024.

Management of Neurofibromatosis Type 2-Associated Vestibular Schwannomas

Neurofibromatosis type 2 (NF2) is an autosomal dominant syndrome caused by a mutation in the NF2 suppressor gene and is characterized by the development of multiple benign tumors throughout the central nervous system. Bilateral vestibular schwannomas (VSs) are pathognomonic for NF2 and are associated with progressive hearing loss and eventual deafness in most patients. This review presents current management options for NF-2-associated VSs.

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.

Clinical implications of intraoperative eABRs to the Evo®-CI electrode array recipients

INTRODUCTION

Electrically evoked auditory brainstem responses provide reliable clinical information to assist professionals in the auditory rehabilitation of cochlear implant users.

OBJECTIVE

This study aimed to investigate intraoperative evoked auditory brainstem response recordings in Evo®-cochlear implant electrode array recipients and its correlation with their behavioral levels and auditory performance.

METHODS

This is a retrospectivey study. Intraoperative evoked auditory brainstem responses were recorded in adult Evo®-cochlear implant electrode array recipients. Wave V latencies, amplitudes and interpeak III-V intervals were recorded in three different electrode locations and compared to the sentence recognition scores obtained from subjects after six months of device use. Evoked auditory brainstem responses thresholds were also recorded and compared to the behaviorally determined levels of the subjects in the sound processor activation.

RESULTS

Evoked auditory brainstem responses thresholds were significantly correlated with both, behavioral T- and C-levels and they were recorded at audible electrical stimulation levels in all subjects. There was a significant correlation between interpeak III-V interval recorded in the apical electrode and sentence recognition scores of the subjects.

CONCLUSIONS

Intraoperative evoked auditory brainstem responses can be used to establish audible levels for fitting the sound processor in Evo®-cochlear implant recipients and it could help professionals to plan further actions aiming to improve their auditory performance.

Ipsilateral Cochlear Implantation in the Presence of Observed and Irradiated Vestibular Schwannomas

OBJECTIVES

Historically, eventual loss of cochlear nerve function has limited patients with neurofibromatosis type 2 (NF2) to auditory brainstem implants (ABI), which in general are less effective than modern cochlear implants (CI). Our objective is to evaluate hearing outcomes following ipsilateral cochlear implantation in patients with NF2 and irradiated vestibular schwannomas (VS), and sporadic VS that have been irradiated or observed.

METHODS

Multi-center retrospective analysis of ipsilateral cochlear implantation in the presence of observed and irradiated VS. MESH search in NCBI PubMed database between 1992 and 2019 for reported cases of cochlear implantation with unresected vestibular schwannoma.

RESULTS

Seven patients underwent ipsilateral cochlear implantation in the presence of observed or irradiated vestibular schwannomas. Four patients had sporadic tumors with severe-profound contralateral hearing loss caused by presbycusis/hereditary sensorineural hearing loss, and three patients with NF2 lost contralateral hearing after prior surgical resection. Prior to implantation, one VS was observed without growth for a period of 7 years and the others were treated with radiotherapy. Mean post-operative sentence score was 63.9% (range 48-91) at an average of 28 (range 2-84) months follow up. All patients in this cohort obtained open set speech perception. While analysis of the literature is limited by heterogenous data reporting, 85% of implants with observed schwannomas achieved some open set perception, and 67% of patients previously radiated schwannomas. Furthermore, blending literature outcomes for post implantation sentence testing in quiet without lip-reading show 59.0 ± 35% for patients with CI and observed tumors and 55.7 ± 35% for patients with radiated tumors, with both groups ranging 0 to 100%.

CONCLUSION

This retrospective series and literature review highlight that hearing outcomes with CI for VS patients are superior to those achieved with ABI. However, important considerations including imaging, delayed hearing loss, and observation time cannot be ignored in this population.

Hearing Response Following Internal Auditory Canal Decompression in Neurofibromatosis Type 2

BACKGROUND

Hearing response following an osteodural decompression of the internal auditory canal (IAC) is controversial.

OBJECTIVE

To evaluate the course of auditory brainstem responses (ABRs) and the early hearing response during the first year following IAC decompression for small to medium-sized vestibular schwannomas occurring in neurofibromatosis type 2 (NF2).

METHODS

Retrospective chart review of middle fossa craniotomy for IAC osteodural decompression in NF2-related vestibular schwannomas.

RESULTS

Twelve NF2 patients were operated on from 2011 to 2016 for IAC decompression. All had NF2 according to the Manchester criteria. All had a progressive change of their ABRs documented from the diagnosis of NF2 over a mean period of 6.25 [0.36;10.9] yr. Treatment was proposed to stop hearing progression based on the speech discrimination scores (SDSs; n = 4) or for hearing maintenance (n = 8). In patients with prior hearing progression, hearing responses were observed in 3 of the 4 patients during the first year. One patient kept on progressing. In the hearing maintenance group, the SDSs remained stable. SDSs improved from 85% [20-100] to 92.5% [60-100] on average (n = 12) and from 55% [20-80] to 77.5% [50-100] in the hearing progression group (n = 4). ABRs improved in 4 patients following decompression.

CONCLUSION

IAC decompression allows early objective hearing responses in select patients. We suggest that the procedure should be offered to patients with hearing progression based on their SDSs and/or associated progressive increases in their wave III and V latencies on ABRs.

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.

Genetic Severity Score predicts clinical phenotype in NF2

​BACKGROUND: The clinical severity of disease in neurofibromatosis type 2 (NF2) is variable. Patients affected with a constitutional truncating NF2 mutation have severe disease, while missense mutations or mosaic mutations present with a milder attenuated phenotype. Genotype-derived natural history data are important to inform discussions on prognosis and management.

METHODS

We have assessed NF2 clinical phenotype in 142 patients in relation to the UK NF2 Genetic Severity Score to validate its use as a clinical and research tool.

RESULTS

The Genetic Severity Score showed significant correlations across 10 measures, including mean age at diagnosis, proportion of patients with bilateral vestibular schwannomas, presence of intracranial meningioma, spinal meningioma and spinal schwannoma, NF2 eye features, hearing grade, age at first radiotherapy, age at first surgery and age starting bevacizumab. In addition there was moderate but significant correlation with age at loss of useful hearing, and weak but significant correlations for mean age at death, quality of life, last optimum Speech Discrimination Score and total number of major interventions. Patients with severe disease presented at a younger age had a higher disease burden and greater requirement of intervention than patients with mild and moderate disease.

CONCLUSIONS

This study validates the UK NF2 Genetic Severity Score to stratify patients with NF2 for both clinical use and natural history studies.

Contemporary imaging of auditory implants

There have been significant advances in the diversity and effectiveness of hearing technologies in recent years. Implanted auditory devices may be divided into those that stimulate the cochlear hair cells (bone conduction devices and middle ear implants), and those that stimulate the neural structures (cochlear implants and central auditory implants). Contemporary preoperative and postoperative imaging may be used to help individualise implant selection, optimise surgical technique and predict auditory outcome. This review will introduce the concepts behind auditory implants, and explains how imaging is increasingly used to aid insertion and evaluation of these devices.

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.

Auditory brainstem implant program development

OBJECTIVE

Auditory brainstem implants (ABIs), which have previously been used to restore auditory perception to deaf patients with neurofibromatosis type 2 (NF2), are now being utilized in other situations, including treatment of congenitally deaf children with cochlear malformations or cochlear nerve deficiencies. Concurrent with this expansion of indications, the number of centers placing and expressing interest in placing ABIs has proliferated. Because ABI placement involves posterior fossa craniotomy in order to access the site of implantation on the cochlear nucleus complex of the brainstem and is not without significant risk, we aim to highlight issues important in developing and maintaining successful ABI programs that would be in the best interests of patients.

DATA SOURCES

Especially with pediatric patients, the ultimate benefits of implantation will be known only after years of growth and development. These benefits have yet to be fully elucidated and continue to be an area of controversy. The limited number of publications in this area were reviewed.

REVIEW METHODS

Review of the current literature was performed.

RESULTS

Disease processes, risk/benefit analyses, degrees of evidence, and U.S. Food and Drug Administration approvals differ among various categories of patients in whom auditory brainstem implantation could be considered for use.

CONCLUSION

We suggest sets of criteria necessary for the development of successful and sustaining ABI programs, including programs for NF2 patients, postlingually deafened adult nonneurofibromatosis type 2 patients, and congenitally deaf pediatric patients. Laryngoscope, 127:1909-1915, 2017.

Neurofibromatosis type 2 service delivery in England

Neurofibromatosis type 2 (NF2) is a complex disease characterized by the development of multiple schwannomas, especially vestibular schwannomas, as well as other types of benign tumours including meningioma and spinal ependymoma. Due to its multisystem nature, the management of NF2 requires a multidisciplinary approach. In England, the delivery of care for NF2 patients has been centralized to four-"hub" centres in Manchester, Cambridge, Oxford and London each having associated "spoke" centres. Each centre has a core multidisciplinary team consisting of genetics, otolaryngology, neurosurgery, paediatrics, neurology, audiology, radiology, psychology, physiotherapy, specialist nurses and administrative staff. In addition, the core team has access to plastic surgery, ophthalmology, peripheral nerve surgery and adult and paediatric oncology. There are weekly multidisciplinary clinics each with six to eight patients. Each patient is discussed during a team meeting and the management decisions that are made are then discussed with the patients. All patients are reviewed at least annually and have annual head magnetic resonance imaging (MRI) and three yearly spinal MRI. Annual audiological assessment is performed. Cochlear implantation and auditory brainstem implantation are offered if indicated. Surgery, stereotactic radiosurgery and bevacizumab therapy are available for the management of intracranial and spinal tumours. The integration of the service in England has provided significant benefits to patient care and, in the long term, will provide robust patient outcome data that will provide an evidence base to assist in optimizing management of patients with NF2.

Auditory brainstem implantation: anatomy and approaches

BACKGROUND

Auditory brainstem implantation at the cochlear nuclei used mainly for neurofibromatosis type 2 patients with bilateral loss of the cochlear nerves has more recently been extended to the inferior colliculus.

OBJECTIVE

To examine the microsurgical and endoscopic anatomy of the cochlear nuclei and inferior colliculus as seen through the translabyrinthine and retrosigmoid approaches used for cochlear nuclei and inferior collicular implantation.

METHODS

Ten cerebellopontine angles of formalin-fixed adult cadaveric heads were examined with the aid of the surgical microscope and endoscope. The ascending auditory pathways between the cochlear nuclei and inferior colliculi and above were examined by the fiber dissection technique.

RESULTS

Both the translabyrinthine and retrosigmoid routes provide sufficient exposure for concurrent tumor removal and implantation at either the cochlear nuclei or inferior colliculus. The position of the inferior colliculus in the auditory pathways and its accessibility in the infratentorial supracerebellar exposure directed through either the translabyrinthine or retrosigmoid approach makes it an alternative site for electrode placement if the cochlear nuclei are not functionally or structurally suitable for implantation. Endoscopic assistance may aid the exposure and electrode placement at either site.

CONCLUSION

The translabyrinthine or retrosigmoid approaches provide access to the cochlear nuclei for implantation and also to the inferior colliculus through the translabyrinthine or retrosigmoid infratentorial supracerebellar route. The endoscope may aid in exposing either site.

Self-reported benefit, sound perception, and quality-of-life in patients with auditory brainstem implants (ABIs)

CONCLUSION

The majority of the patients used their auditory brainstem implants (ABIs) all the time, reporting that he/she would make the decision to receive an implant again if the decision were reconsidered. The findings support that the ABI is a valuable treatment in patients with type 2 neurofibromatosis (NF2) and in children with congenital inner ear and nerve anomalies or cochlear ossification.

OBJECTIVE

To evaluate the patients who underwent ABI implantation in Uppsala during 1993-2013. This study analyzed patients' implant use, perception of environmental sounds, perceived benefit from the implant, and quality-of-life (QoL).

METHOD

The NF2-patients (n = 20) comprised the majority of the patients, and there were a few non-NF2 pediatric patients (n = 4). The exclusion criteria included deceased patients (n = 4) and patients with no hearing sensations from the implant, or those with an inactivated ABI (n = 2). The data were collected from a questionnaire survey.

RESULTS

Eleven adult patients and two pediatric patients answered the questionnaires. Eight of the adult patients used their implants 'always'. The two children always used their implants. Hearing problems had the largest negative effect on the QoL. The non-users and the users scored equally on the NFTI-QoL.

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.

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.