[Neurofibromatosis type 2 and auditory brainstem implantation]. / Nevrofibromatose type 2 og auditorisk hjernestammeimplantat.

BACKGROUND: Neurofibromatosis type 2 (NF2) is a rare and severe autosomal dominant disorder caused by mutations in a tumour suppressor gene. This article reviews NF2 and its treatment with auditory brainstem implantation. MATERIAL AND METHODS: The review is based on the authors' experience with the disease and literature identified through a non-systematic search of PubMed. RESULTS: NF2 is caused by loss-of-normal function of the tumour suppressor protein merlin. Merlin normally suppresses cell growth and proliferation. The clinical picture is dominated by neurological symptoms, caused by multiple tumours - mainly schwannomas and meningeomas. The hallmark of the disease is development of bilateral vestibular schwannomas, and the most common presenting symptom in adults is progressive hearing loss. Presenile cataract, ocular motility disorders, peripheral neuropathy and skin tumours are other common findings. The majority of patients become deaf, many patients become severely disabled and life expectancy is reduced. The goal of management is conservation of function and maintenance of quality of life. Auditory brainstem implants stimulate the cochlear nucleus directly and provide substantial auditory benefits to patients with NF2. INTERPRETATION: A multidisciplinary approach in specialty centres is recommended. Management by an experienced team reduces mortality and improves outcome after surgery. Auditory brainstem implantation is an important part of the hearing rehabilitation in these patients. Emerging knowledge of the molecular disease mechanisms offers hope for new therapeutic strategies.

First report of the efficacy of vestibular rehabilitation in improving function in patients with Neurofibromatosis type 2: an observational cohort study in a clinical setting.

PURPOSE: Patients with Neurofibromatosis type 2 often experience debilitating neuro-otological problems which affect their mobility and balance. This study examined the efficacy of a personalised program of vestibular rehabilitation for patients with Neurofibromatosis type 2. MATERIALS AND METHODS: An observational cohort study analysing routinely collected data for 21 patients in a highly specialised Neurofibromatosis type 2 service. Vestibular rehabilitation comprised an initial one-hour assessment followed by a patient-specific exercise program reviewed in person and by email consultations. Patients were subsequently followed-up at 9 months. The vestibular rehabilitation efficacy was assessed using the Dynamic Gait Index score. RESULTS: Nineteen of 21 patients were assessed as impaired and at risk of falls pre-rehabilitation (Dynamic Gait Index <19/24), of which 79% showed clinical improvement post-rehabilitation. There was a significant improvement in the Dynamic Gait Index scores pre-rehabilitation to post-rehabilitation (p < 0.001) and outcomes were subsequently maintained at the 9-month follow-up assessment. Whilst the pre-rehabilitation Dynamic Gait Index scores of patients with more severe genotype were lower compared to other patients, the beneficial effect of vestibular rehabilitation was similar amongst genetic severity groups. CONCLUSIONS: Personalised vestibular rehabilitation significantly improves function in Neurofibromatosis type 2, sustaining benefits for 9 months, irrespective of patients' age or genetic severity. Implications for rehabilitation Patients with Neurofibromatosis type 2 experience debilitating neuro-otological problems which affect their mobility and balance. A patient-tailored program of vestibular rehabilitation was offered in a highly specialised clinic for six months with a follow-up assessment at 9 months post-treatment. All patients improved from baseline, with 79% of them achieving clinically significant improvement in function and with statistically significant benefits sustained for 9 months. The beneficial effect of vestibular rehabilitation was similar for all patients, regardless of age or genetic severity, suggesting vestibular rehabilitation could be incorporated in routine clinical care in Neurofibromatosis type 2 clinics internationally.

Hearing rehabilitation in neurofibromatosis type 2 patients: cochlear versus auditory brainstem implantation.

OBJECTIVE: We aimed to evaluate and compare the auditory performance of neurofibromatosis type 2 (NF2) patients with bilateral total deafness fitted with cochlear or auditory brainstem implants. PATIENTS AND METHODS: A retrospective case review was performed. Nine patients suffering from NF2 who underwent hearing rehabilitation by means of cochlear (4 patients) or auditory brainstem (5 patients) implantation participated in the study. Postoperative auditory performance was assessed using closed- and open-set tests. RESULTS: In the group of patients fitted with a cochlear implant, 3 subjects achieved open-set speech recognition abilities comparable to those of standard adult postlingual implant patients; the remaining patient scored 0% in all open-set format tests, reporting benefits only in environmental sound detection and lip-reading. Among the 5 patients who underwent auditory brainstem implantation, 1 reached good open-set speech recognition skills, scoring 70% in the common phrases comprehension test, and she was able to communicate on the telephone. Two other patients achieved open-set speech understanding (respectively, 33 and 41% in the common phrases comprehension test), reporting daily use of their device. The remaining 2 patients did not achieve any level of open-set speech perception, obtaining only improved access to environmental sound and lip-reading skills. CONCLUSIONS: Our study confirmed literature data reporting that cochlear implantation may offer open-set speech communication in NF2 patients. In this small cohort, cochlear implant patients performed better than auditory brainstem implant patients, even if variability in auditory performance was observed with both devices. More studies are needed in order to clarify the role and reliability of electrophysiological tests in predicting the residual functionality of the cochlear nerve after tumor removal.

Rehabilitation of hearing and communication functions in patients with NF2.

Most patients with neurofibromatosis type 2 (NF2) lose hearing either spontaneously or after removal of their neurofibromas. The patient may benefit from conventional hearing aids if, due to modern microsurgery and intraoperative monitoring the integrity of the cochlea and the 8th nerve is preserved. With lost auditory function but preserved electrical stimulibility of the 8th nerve a cochlear implant may be appropriate. But if the patients have no remaining 8th nerve to stimulate, there is no benefit from cochlear implants. Until some years ago, vibrotactile aids, lip-reading, and sign language have been the only communication modes available to these patients. With auditory brain stem implants it is now possible to bypass both the cochlea and the 8th nerve and to stimulate the cochlear nucleus directly. Stimulation of the devices produces useful auditory sensations in almost all patients. Testing of perceptual performance indicated significant benefit from the device for communication purposes, including sound-only sentence recognition scores and the ability to converse on the telephone. Also lip-reading is significantly improved with brain stem implants. The successful work of an auditory brainstem program center depends very much on the close interdisciplinary collaboration between the Departments of Neurosurgery and ENT-surgery. In the future new developments like speech processing strategies and new designed electrodes accessing the complex tonotopic organization of the cochlear nucleus may further improve rehabilitation in these patients who would have been deaf some years ago.

Surgical management of vestibular schwannomas and hearing rehabilitation in neurofibromatosis type 2.

OBJECTIVES: To report our approach to the surgical management of vestibular schwannomas (VSs) and hearing rehabilitation in neurofibromatosis Type 2 (NF2). DESIGN: Retrospective cohort study. SETTING: Tertiary referral NF2 unit. PATIENTS: Between 1981 and 2011, seventy-five patients were managed in our NF2 unit, of which, 58 patients are under current review. MAIN OUTCOME MEASURES: Patients who underwent VS excision were evaluated for tumor size, surgical approach, and outcomes of hearing and facial nerve function. All current patients were evaluated for NF2 mutation, hearing, and auditory implantation outcomes. RESULTS: Forty-four patients underwent resection of 50 VS in our unit, of which, 14% had facial neuroma excision and reinnervation during the same operation. At 12 months after surgery, facial nerve outcomes were House-Brackmann (HB) 1 in 33%, HB2 in 21%, and HB3 in 30%. Total VS resection was achieved in 78% of patients using a translabyrinthine approach. Seventy-two percent of the current patients have American Association of Otolaryngology-Head and Neck Surgery class A to C hearing (maximum speech discrimination score over 50%) in the better hearing ear, and a further 14% are full-time users of cochlear implants or auditory brainstem implants. The remaining patients have been assessed for auditory implantation. CONCLUSION: By following a policy of treating VS in NF2 patients where tumor growth is observed, complete tumor resection can be achieved through a translabyrinthine approach while achieving comparable facial nerve outcomes to published series. We advocate proactive hearing rehabilitation in all patients with timely assessment for auditory implantation to maintain quality of life.

Auditory brainstem implants in NF2 patients: results and review of the literature.

OBJECTIVE: Neurofibromatosis Type 2 (NF2) patients have multiple central nervous system tumors and, specifically, bilateral vestibular schwannomas (VSs) causing bilateral deafness. If the cochlear nerve is not preserved during tumor removal, the only hearing rehabilitation in these patients could be via an auditory brainstem implant (ABI). STUDY DESIGN: Retrospective case study and literature review. SETTING: Tertiary referral cranial base center. PATIENTS: In 24 NF2 patients, 25 ABIs were placed in the lateral recess of the fourth ventricle after VS surgery via a translabyrinthine approach. RESULTS: In this series, a large range of results are observed: from open speech and use of the telephone to no ABI use, because of the poor sound identification ability. Of the 24 patients, 19 use their ABI on a daily basis, 4 are nonusers, and 1 died of NF2 progression. A multivariate analysis did not reveal a good predictor for ABI outcome. In literature, the results of ABI in NF2 are difficult to compare, and the overall outcome was poor compared with cochlear implantation results. CONCLUSION: Auditory brainstem implantation in NF2 patients directly after tumor removal is a safe procedure and the best means of hearing rehabilitation if the cochlear nerve is not preserved. The results in NF2 cases in the literature and these series are poor compared with cochlear implantation. If a cochlear implant is possible, it has the preference over an ABI, also in NF2. Nevertheless, the majority of the patients have benefit of the ABI during daily life particularly in combination with lip reading.

Cochlear implantation in patients with neurofibromatosis type 2: variables affecting auditory performance.

OBJECTIVE: To investigate cochlear implant performance outcomes among patients with Neurofibromatosis type 2 (NF2). STUDY DESIGN: Retrospective case series, patient questionnaire, and systematic review of the literature. SETTING: Tertiary academic referral center. PATIENTS: All patients with NF2 having an anatomically intact ipsilateral cochlear nerve who underwent cochlear implantation (CI). INTERVENTION(S): Cochlear implantation. MAIN OUTCOME MEASURES: Postimplantation audiometric performance and patient perceived benefit. RESULTS: Ten patients met study criteria. The median duration of follow-up after CI was 42 months (mean, 46.9 mo; range, 12-97 mo). Five patients received previous microsurgical resection of their ipsilateral vestibular schwannoma, 4 underwent previous stereotactic radiosurgery, and 1 patient had no tumor treatment before CI. Nine subjects achieved sound awareness, 6 attained open-set speech recognition and 7 are daily users. Variables including prolonged auditory deprivation, cochlear ossification, unfavorable electrical promontory stimulation testing, and useful contralateral hearing were associated with poor cochlear implant performance. No statistical associations were found between open-set recognition capacity and previous tumor management strategy, surgical approach, or ipsilateral tumor size. CONCLUSION: Cochlear implantation is an attractive alternative to auditory brainstem implantation for hearing rehabilitation in patients with NF2. Approximately 70% of patients achieve open-set speech discrimination, many scoring at the ceiling of audiometric testing. Given a favorable risk profile and superior audiometric outcomes, CI should be strongly considered in patients with nonserviceable hearing who have an anatomically intact cochlear nerve, whereas auditory brainstem implantation should be reserved for patients with evidence of cochlear nerve loss. Akin to conventional cochlear implant recipients, prolonged hearing loss, unfavorable electrophysiological testing, and cochlear ossification may predict poor subject performance. Finally, useful hearing in the contralateral ear may present a barrier to daily device use.

Auditory rehabilitation of patients with neurofibromatosis Type 2 by using cochlear implants.

OBJECT: The aim of this study was to determine whether patients with neurofibromatosis Type 2 (NF2) who have intact ipsilateral cochlear nerves can have open-set speech discrimination following cochlear implantation. METHODS: Records of 7 patients with documented NF2 were reviewed to determine speech discrimination outcomes following cochlear implantation. Outcomes were measured using consonant-nucleus-consonant words and phonemes; Hearing in Noise Test sentences in quiet; and City University of New York sentences in quiet and in noise. RESULTS: Preoperatively, none of the patients had open-set speech discrimination. Five of the 7 patients had previously undergone excision of ipsilateral vestibular schwannoma (VS). One of the patients who received a cochlear implant had received radiation therapy for ipsilateral VS, and another was undergoing observation for a small ipsilateral VS. Following cochlear implantation, 4 of 7 patients with NF2 had open-set speech discrimination following cochlear implantation during extended follow-up (15-120 months). Two of the 3 patients without open-set speech understanding had a prolonged period between ipsilateral VS resection and cochlear implantation (120 and 132 months), and had cochlear ossification at the time of implantation. The other patient without open-set speech understanding had good contralateral hearing at the time of cochlear implantation. Despite these findings, 6 of the 7 patients were daily users of their cochlear implants, and the seventh is an occasional user, indicating that all of the patients subjectively gained some benefit from their implants. CONCLUSIONS: Cochlear implantation can provide long-term auditory rehabilitation, with open-set speech discrimination for patients with NF2 who have intact ipsilateral cochlear nerves. Factors that can affect implant performance include the following: 1) a prolonged time between VS resection and implantation; and 2) cochlear ossification.

Update on long-term results with auditory brainstem implants in NF2 patients.

This study reviews the long-term results of auditory brainstem implant (ABI) in neurofibromatosis type 2 (NF2) patients. Retrospective chart reviews of patients who received an ABI at the Melbourne Cochlear Implant Clinic since 1995. Ten patients with an average follow-up of five years were included. Three patients received the N22 ABI and seven received the N24. Two patients discontinued use of their devices. Users reported part-time use for approximately four to five hours per day, switching their implants off in noisy environments. Audiological analyses at one to seven years post-implantation indicate that N24 patients showed worse performance at one year post-implantation but they continued to improve and, in the long term, both N22 and N24 groups achieved similar results. In conclusion, ABI provides a safe and useful tool for aural rehabilitation in NF2 patients. This study confirms that gradual improvement in performance occurs beyond one year post-implantation, as speech perception scores continued to improve.