Metachronous Bilateral Vestibular Schwannomas

Bilateral vestibular schwannoma (BVS) is the hallmark of neurofibromatosis type 2 (NF2), both of them being present at diagnosis. We report four cases of metachronous BVS, a contralateral intracanalicular vestibular schwannomas (VS) being visible 2 to 13 years after resection of a unilateral VS. NF2 workup was negative except in one case where two NF2 gene mutations were found in tumor analysis. These cases raise the questions of whether the contralateral VS occurred by chance and how to manage it on the only hearing ear. Otologists should be aware of this rare eventuality for decision making of the first unilateral VS. Laryngoscope, 131:E250–E254, 2021     

A clinical study of vestibular schwannomas in type 2 neurofibromatosis

All 13 patients with neurofibromatosis 2 (NF2) who presented over a period of 17 years at the Institute of Neurological Sciences, Glasgow were reviewed and compared to patients with sporadic vestibular schwannomas. The NF2 patients presented at a younger age than those with sporadic vestibular schwannomas. A significant number had normal pure tone audiograms and a small number also had normal auditory brainstem responses at presentation. Vestibular schwannomas in NF2 patients grow more often and more rapidly than sporadic unilateral ones. They are more liable to infiltrate the cochlear and facial nerves making hearing and facial nerve preservation more difficult to achieve. Because the relatives of these patients often have normal audiograms and normal auditory brain stem responses in the presence of a schwannoma, our recommended method of screening of relatives of NF2 patients is magnetic resonance image scanning with Gd-DTPA enhancement.     

神经纤维瘤病Ⅱ型基因型与表型研究现况

神经纤维瘤病Ⅱ型(Neurofibromatosis Type 2,NF2)是一种常染色体显性肿瘤易感性综合征,典型临床表现为单侧或双侧听力下降,耳鸣和平衡障碍。前庭神经鞘瘤为该病特征,约95%患者出现双侧前庭神经鞘瘤,许多NF2患者也患有其他组织学上表现为良性的中枢神经系统肿瘤,如脑膜瘤和脊柱内室管膜瘤。该病是由22号染色体上NF2基因的遗传性突变或新发突变引起的。患者面临听力丧失,反复手术切除颅内和脊柱肿瘤,重要功能丧失以及预期寿命缩短。基于基因型与表型相关性研究,早期精准评估患者病情,为患者选择合适干预手段,提供预后相关依据具有重大意义。该篇归纳了NF2基因型与表型相关性研究中的主要进展。     

Management strategies in neurofibromatosis type 2

The objective of this study was to review the experience of the Neurotology and Skull Base Surgery Unit of Addenbrooke's Hospital in Cambridge, England, in the management of patients with neurofibromatosis type 2 (NF2). This was a retrospective review of the institution's series conducted at a neurotological tertiary referral centre. Over a 17-year period (1984-2001), 35 patients with NF2 were managed. These patients presented with multiple cranio-spinal neoplasms, including 62 cerebellopontine angle tumours of which 59 were vestibular schwannomas (nine patients with unilateral tumours and 25 patients with bilateral tumours). Clinical presentation, diagnosis and patient management were reviewed. The outcome parameters measured were tumour progression, the incidence of complications (hearing deterioration and facial nerve palsy) and the need for secondary intervention. Five vestibular schwannomas were treated with stereotactic radiosurgery (gamma-knife), all of which showed evidence of progression in size and/or deterioration in hearing. Thirty-one VS were conservatively treated with annual surveillance. In nine cases, the tumours had a follow-up shorter than 6 months and were therefore excluded from the results. In 13 cases the VS did not progress in size, and the hearing remained stable, while in the remaining nine cases, tumour progression was evident. In fifteen cases, surgery was performed at the authors' institution. In 11 cases a translabyrinthine approach was adopted, and in the remaining four cases a retrosigmoid approach was preferred. In all these cases, tumour removal was total and facial nerve function was House-Brackmann grade I-III in 55%. Successful hearing preservation was elusive in those patients in whom a hearing preservation approach was attempted. NF2 remains an extremely challenging disorder for the neurotologist and the patient alike. Early diagnosis offers distinct advantages to the patients, their families and the community at large. Of the treatment modalities, surgery unequivocally offers the most superior tumour control. Hearing preservation remains a challenge in these patients, but is optimised by the early detection of tumours in the NF2 patient.     

The molecular biology of vestibular schwannomas: dissecting the pathogenic process at the molecular level.

OBJECTIVE: The goal of this article was to review concisely what is currently known about the tumorigenesis of vestibular schwannomas. BACKGROUND: Recent advances in molecular biology have led to a better understanding of the cause of vestibular schwannomas. Mutations in the neurofibromatosis type 2 tumor suppressor gene (NF2) have been identified in these tumors. In addition, the interactions of merlin, the protein product of the NF2 gene, and other cellular proteins are beginning to give us a better idea of NF2 function and the pathogenesis of vestibular schwannomas. METHODS: Review of the relevant basic science studies at our institution as well as the basic science and clinical literature. RESULTS: The clinical characteristics of vestibular schwannomas and neurofibromatosis type 2 syndromes are reviewed and related to alterations in the NF2 gene. Studies demonstrating our current understanding of tumor developmental pathways are highlighted. In addition, methods of clinical and genetic screening for neurofibromatosis type 2 disease are outlined. Avenues for the development of potential future research and therapies are discussed. CONCLUSION: Great strides have been made to identify why vestibular schwannomas develop at the molecular level. Continued research is needed to find targeted therapies with which to treat these tumors.     

神经纤维瘤病Ⅱ型(附1例报告)

目的：提高对神经纤维瘤病Ⅱ型（NF2）的病因、临床表现、诊断及治疗的认识。方法：结合文献复习,分析我院收治的1例NF2患者的临床资料,并对该例患者行左侧小脑桥脑角肿瘤切除术。结果：该患者患病年龄较早,出现临床症状较晚,首发症状为渐进性听力下降伴耳鸣,头颅MRI示双侧小脑桥脑角占位性病变,双侧海绵窦区及双侧颈部多发结节。组织病理性质为神经鞘膜瘤。术后左耳全聋,左侧不完全性周围性面神经麻痹,House-Brackmann分级Ⅱ级。结论：NF2为常染色体显性遗传疾病,临床上以双侧听神经瘤为主要特征。早期诊断和治疗对患者的听力和生命的保护至关重要。MRI扫描为目前诊断NF2的金标准。     

The limitations of computed tomography in adult cochlear implant evaluation

Objective

To demonstrate the added value of magnetic resonance imaging (MRI) over computed tomography (CT) during adult cochlear implant evaluation.

Patients

Two adult patients are discussed in whom MRI studies diagnosed bilateral vestibular schwannomas during cochlear implant candidacy evaluation.

Interventions

Temporal bone CT and MRI.

Main outcome measure

Diagnosis of NF2.

Results

Two adult patients, ages 67 and 68 years, were evaluated for cochlear implant candidacy. Both patients experienced slowly progressive, bilateral hearing loss without complaints of vertigo, and neither patient had a family history of hearing loss or neurogenic tumors. Both patients had near-symmetric pure tone thresholds on audiometric testing. An MRI and a CT scan were performed on both patients, and bilateral vestibular schwannomas were identified on MRI.

Conclusions

Though MRI is not routinely utilized in adult cochlear implant evaluation, it may be of greater clinical value than CT in the setting of adult-onset hearing loss. MRI allows for sensitive evaluation of cochlear patency and architecture, and cochlear nerve status. As demonstrated in the two index cases, MRI also provides the added benefit of evaluating for causes of retrocochlear hearing loss. These two patients would have likely experienced a significant delay in diagnosis of NF2 without preoperative MRI, particularly given the limitations of scanning following CI magnet placement.     

Cochlear implantation in the neurofibromatosis type 2 patient: long-term follow-up

OBJECTIVE: To evaluate the long-term hearing outcomes of neurofibromatosis type 2 (NF2) patients with cochlear implants. METHODS: Retrospective analysis of cochlear implant performance in NF2 patients using open- and closed-set speech perception testing. RESULTS: Patients with NF2-associated bilateral vestibular schwannomas frequently become profoundly deaf. The aim of surgical resection should be to preserve serviceable hearing in at least one ear; however, this goal can be difficult to achieve. Frequently, tumor size or poor preoperative hearing status can require a surgical approach that leaves the patient with a profound, bilateral sensorineural hearing loss. If the cochlear nerve is preserved anatomically after vestibular schwannoma surgery, and if promontory stimulation confirms the functionality of the cochlear nerve, then cochlear implantation is an excellent option to restore hearing. We present six cochlear implant patients with NF2 who attained a significant improvement in open- and closed-set speech understanding with a mean follow-up of 7.9 (range: 5-13) years after surgery. In all but one case, the hearing results did not deteriorate over the follow-up period. CONCLUSION: Early surgical intervention for vestibular schwannomas in NF2 patients when the cochlear nerve can be spared is an important consideration to allow for possible cochlear implantation. A 6- to 8-week recovery period for the anatomically intact cochlear nerve may be necessary to obtain a positive promontory stimulation response following tumor resection and should be performed prior to cochlear implantation.     

Neurofibromatosis type 2: genetic and clinical features

For decades, neurofibromatosis type 2 (NF2) was misclassified with the more common neurofibromatosis type 1 (NF1), until 1987 when it was found via genetic linkage analysis that the gene for NF1 was localized to chromosome 17 and the gene for NF2 was localized to chromosome 22. Large, population-based studies have shown that vestibular schwannomas (VS), the hallmark of NF2, do not occur at increased frequency in patients with NF1. Typical clinical features of NF2 are bilateral VS or a family history of NF2, plus either unilateral VS or any two of the following: meningioma, glioma, neurofibroma, schwannoma or posterior subcapsular lenticular opacities. Presymptomatic genetic tests are now possible in the majority of families, and it is hoped that somatic gene therapy will be developed for the treatment of this disease.     

Controversies in building a management algorithm for vestibular schwannomas

PURPOSE OF REVIEW: The present review examines the various mainstream treatment options, benefits and risks, and controversies involved in developing a management algorithm for treatment of vestibular schwannoma. RECENT FINDINGS: Advances in microsurgery and radiosurgery have made tremendous contributions to management of vestibular schwannoma; however, considerable controversy still exists. The auditory and facial nerve functional outcomes have improved with use of intraoperative monitoring for vestibular schwannoma removal and with lower radiosurgery doses; however, risks to the facial and auditory nerves still exist. Observing vestibular schwannomas for growth with serial magnetic resonance imaging is an increasingly popular option for small vestibular schwannomas that allows patients to enjoy hearing and facial function. SUMMARY: The risks and benefits of each treatment option must be weighed for each patient, and management decisions regarding vestibular schwannomas should be individualized for each patient depending on tumor anatomy, patient preferences, and symptoms.     

Extended translabyrinthine approach in treatment of vestibular schwannomas

Results of removal of vestibular schwannomas using translabyrintine approach were presented. 12 unilateral neuromas were operated. Large neuromas with diameter above 2 cm constituted 75% of all cases. The total resection of tumors was achieved in 10 patients. In all cases anatomical integrity of facial nerve was conserved. In 7 patients facial nerve function was in stage I-III (House Brackmann classification). There were not life threatening complications. Authors underline, that the translabyrintine approach permits to obtain enough wide insight to ponto-cerebellar angle to remove safely, both little and large, vestibular schwannomas.     

Surgical outcomes of middle fossa approach in intracanalicular vestibular schwannoma

Abstract

Conclusion: Middle fossa approach (MFA) shows a hearing preservation rate of 86% and facial nerve function was preserved with HB grade I or II in 93%. MFA is a good treatment option for intra-canalicular vestibular schwannomas when surgical excision is needed.

Background: Surgical outcomes of vestibular schwannoma have progressively improved with the advancement of microsurgical instruments. MFA is known to have better chances to preserve hearing, while it has limited access to the posterior fossa, limitation of tumor size, and higher risk of post-operative facial nerve weakness.

Objectives: To investigate surgical outcomes and clinical efficiency of MFA in vestibular schwannoma.

Methods: A retrospective study was done in 14 patients who underwent MFA for vestibular schwannoma in Asan Medical Center.

Results: The median age at diagnosis was 46.3 years. At initial presentation, 57% of the patients had vertigo, 43% hearing disturbance, and 64% tinnitus. The mean tumor size was 9.7?mm. The tumors were completely resected in 86% of the patients. Hearing was post-operatively preserved in 12 patients and two patients lost their hearing following surgery. Facial nerve function post-operatively remained unchanged in 12 patients (86%).     

Changes in Ribbon Synapses and Rough Endoplasmic Reticulum of Rat Utricular Macular Hair Cells in Weightlessness

Although still the subject of discussion, vestibular-evoked myogenic potentials (VEMPs) have been considered to reflect the function of the saccular and, more recently, the cochlear tracts. To accurately determine the precise afferent pathway carrying VEMPs, we studied the outcomes of VEMPs and other examinations in patients with unilateral vestibular schwannomas. Eleven patients with unilateral vestibular schwannomas resected using a middle cranial fossa approach were included in the study. Patients underwent pure-tone threshold audiometry, caloric tests and analysis of auditory brainstem responses (ABRs) and VEMPs pre- and postoperatively. The results were compared with those obtained in patients with intact superior or inferior vestibular and cochlear nerves. Among the 11 patients studied, 4 retained their VEMPs postoperatively. Three of the 10 patients with inferior vestibular schwannomas exhibited normal VEMPs, preserved hearing levels (20 dB HL) and anatomically intact superior vestibular nerves. In all of these cases, ABRs more closely correlated with VEMPs than with caloric responses. In one of the cases with inferior vestibular schwannomas, VEMPs were preserved postoperatively and VEMP latencies were shortened, which indicates the preoperative presence of a conduction block in either the cochlear or superior vestibular nerve. VEMPs may be conducted in both the superior vestibular and cochlear nerves, as well as in the inferior vestibular nerve. Thus, evaluation of saccular nerve function should be performed carefully, especially in cases where hearing is preserved. It appears that cochlear conduction may proceed along two pathways, one direct and the other via the brainstem, but this remains to be verified.     

Our surgical experience with large vestibular schwannomas

Our aim is to remove large vestibular schwannomas (VS) radically with minimal morbidity. Usually, these tumours cannot not be treated by irradiation. In the years 1997-2003, 69 VS were operated in the Department of Otorhinolaryngology, Head and Neck Surgery of the First Medical Faculty in Prague, Czech Republic. Prevailing majority of these tumours were of the 4th grade (House classification), compressing the brainstem. Six patients in the group suffered from neurofibromatosis 2, in five cases the patients were indicated for neurosurgery due to rapid tumour growth after previous irradiation. All tumours were radically removed using a retromastoid osteoplastic and translab approach with an intraoperative nerve monitoring. Good function of the facial nerve was achieved in 90%. The nerve had to be resutured in 4 cases with consequent satisfactory results, cross anatomosis was not performed. Hearing function was preserved in 8% of patients only. In 6 patients with neurofibromatosis 2, the auditory brainstem implant (ABI) was used to preserve hearing. This study demonstrates that a radical removal of large vestibular schwannomas is possible using a minimally invasive surgical technique and peroperative nerve monitoring with a good impact on quality of life. Auditory brainstem implants bring a new chance of hearing after tumour removal in patients with NF2.     

Postoperative vestibular-evoked myogenic potentials in cases with vestibular schwannomas

Although still the subject of discussion, vestibular-evoked myogenic potentials (VEMPs) have been considered to reflect the function of the saccular and, more recently, the cochlear tracts. To accurately determine the precise afferent pathway carrying VEMPs, we studied the outcomes of VEMPs and other examinations in patients with unilateral vestibular schwannomas. Eleven patients with unilateral vestibular schwannomas resected using a middle cranial fossa approach were included in the study. Patients underwent pure-tone threshold audiometry, caloric tests and analysis of auditory brainstem responses (ABRs) and VEMPs pre- and postoperatively. The results were compared with those obtained in patients with intact superior or inferior vestibular and cochlear nerves. Among the 11 patients studied, 4 retained their VEMPs postoperatively. Three of the 10 patients with inferior vestibular schwannomas exhibited normal VEMPs, preserved hearing levels (20 dB HL) and anatomically intact superior vestibular nerves. In all of these cases, ABRs more closely correlated with VEMPs than with caloric responses. In one of the cases with inferior vestibular schwannomas, VEMPs were preserved postoperatively and VEMP latencies were shortened, which indicates the preoperative presence of a conduction block in either the cochlear or superior vestibular nerve. VEMPs may be conducted in both the superior vestibular and cochlear nerves, as well as in the inferior vestibular nerve. Thus, evaluation of saccular nerve function should be performed carefully, especially in cases where hearing is preserved. It appears that cochlear conduction may proceed along two pathways, one direct and the other via the brainstem, but this remains to be verified.     

Posterior circulation ischemic stroke in childhood and neurofibromatosis type 2

Neurofibromatosis 2 (NF2) is a genetically inherited tumor predisposition syndrome. It predisposes to the development of multiple tumors of the central nervous system including schwannomas, meningiomas and ependymomas. Bilateral vestibular schwannomas (VS) are pathognomonic for the disease. In childhood, non-auditory symptoms often mark the onset of the NF2, such as facial palsy, peripheral neuropathy, and neurosurgical emergencies. In this article, we describe the case of a 6-year-old child presenting with an ischemic brain-stem stroke, who was later diagnosed with NF2. We report the clinical and genetic findings and review the previous literature on vasculopathy reported in association with NF2, with a focus on the symptoms presenting at disease onset. For our case patient, an unpublished germline mutation resulting in frameshift (c.876_877insT) was identified on blood screening. We report our full multidisciplinary assessment with vascular angiography, volumetric MRI and audiometry. Vasculopathy is not currently included in the criteria traditionally used for diagnosis of NF2. We suggest that vascular stroke in childhood may be considered a presenting symptom for NF2.     

Inner ear and facial nerve complications of acute otitis media with focus on bacteriology and virology

Conclusion. Among 20 patients with inner ear complications and/or peripheral facial palsy secondary to acute otitis media (AOM) a proven or probable bacteriological cause was found in 13 (65%). In seven patients (35%), a proven or probable viral cause was found. Only two of the patients (10%), with a proven bacterial AOM and a clinical picture of a purulent labyrinthitis in both, together with a facial palsy in one, had a substantial degree of dysfunction. Although the number of patients in this study is relatively low our findings show that inner ear complications and facial palsy due to AOM can be of both bacterial and viral origin. Severe sequelae were found only where a bacterial origin was proven. Objectives. Inner ear complications and/or peripheral facial palsy secondary to AOM are rare. The general understanding is that they are due to bacterial infections. However, in some of these patients there are no clinical or laboratory signs of bacterial infections and they have negative bacterial cultures. During recent years different viruses have been isolated from the middle ear or serologically proven in AOM patients and are thought to play a pathogenetic role. We suggest that in some cases of AOM complications from the inner ear and the facial nerve can be caused by viruses. The purpose of our study was to analyze infectious agents present in patients with inner ear complications and/or facial palsy arising from AOM. Patients and methods. The medical records of 20 patients who had inner ear complications and/or facial palsy following AOM ( unilateral in 18, bilateral in 2) between January 1989 and March 2003 were evaluated. Bacterial cultures were carried out for all patients. Sera from 12 of the patients were stored and tested for a battery of specific viral antibodies. In three patients, investigated between November 2002 and March 2003, viral cultures were also performed on samples from the middle ear and nasopharynx. Results. Nineteen patients had inner ear symptoms. Eight of them had a unilateral sensorineural hearing loss and vertigo, three had vertigo as an isolated symptom and one, with bilateral AOM, had bilateral sensorineural hearing loss. Seven patients had a combination of facial palsy and inner ear symptoms (unilateral sensorineural hearing loss in three, unilateral sensorineural hearing loss and vertigo in two, bilateral sensorineural hearing loss and vertigo in one, with bilateral AOM, and vertigo alone in one). One patient had an isolated facial palsy. Healing was complete in 11 of the 20 patients. In seven patients a minor defect remained at follow-up (a sensorineural hearing loss at higher frequencies in all). Only two patients had obvious defects (a pronounced hearing loss in combination with a moderate to severe facial palsy (House-Brackman grade 4) in one, distinct vestibular symptoms and a total caloric loss in combination with a high-frequency loss in the other. Eight patients had positive bacteriological cultures from middle ear contents: Streptococcus pneumoniae in two, beta-hemolytic Streptococcus group A in two, beta-hemolytic Streptococcus group A together with Staphylococcus aureus in one, Staph. aureus alone in one and coagulase-negative staphylococci (interpreted as pathogens) in two. In the 12 patients with negative cultures, there was a probable bacteriological cause due to the outcome in SR/CRP and leukocyte count in five. In four patients serological testing showed a concomitant viral infection that was interpreted to be the cause (varicella zoster virus in two, herpes simplex virus in one and adenovirus in one.) In three there was a probable viral cause despite negative viral antibody test due to normal outcome in SR/CRP, normal leukocyte count, serous fluid at myringotomy and a relatively short pre-complication antibiotic treatment period.     

Nerve of origin, tumor size, hearing preservation, and facial nerve outcomes in 359 vestibular schwannoma resections at a tertiary care academic center

Objective: To determine nerve of origin, tumor size, hearing preservation rates, and facial nerve outcomes in a retrospective cohort study of patients undergoing translabyrinthine (TL), middle cranial fossa (MCF), and retrosigmoid/suboccipital (SO) approaches to vestibular schwannomas (VS). Study Design: Retrospective. Methods: Chart review. Results: Patient charts from 231 TL, 70 MCF, 53 SO, and 5 combined TL/SO procedures for VS were evaluated in 356 patients. The inferior vestibular nerve (IVN) was the nerve of origin in 84 of 359 cases (23.3%), while the superior vestibular nerve (SVN) was the nerve of origin in 36 patients (10%). In 239 of 359 cases (66.6%), the nerve of origin was not identified. Forty patients undergoing hearing preservation surgery had hearing results and nerve of origin data available for review. Functional hearing (<50dB PTA and >50% speech discrimination) was preserved in 10 of 15 patients (75%) with SVN tumors, while only 7 of 25 patients (28%) with IVN tumors retained functional hearing. Facial nerve outcomes and nerve of origin were recorded simultaneously in 109 patients. Seventy‐one of 74 patients (95%) patients with IVN tumors achieved a House‐Brackmann (HB) grade I–III, while 35 of 35 patients (100%) with SVN tumors retained HB I–III facial function. Looking at tumor size versus hearing preservation, functional hearing was preserved in 22 of 49 patients (45%) with <1‐cm tumors, and 4 of 20 patients (20%) with 1‐ to 1.5‐cm tumors. For all cases with documented facial nerve function, HB I–III were achieved in 96% of SO, 94% of MCF, and 88% of TL procedures. Conclusions: Our retrospective data indicated that IVN tumors were twice as common as SVN tumors. The nerve of origin did not affect facial nerve outcomes but did impact hearing preservation rates. Patients with tumors <1 cm in size had the best chance for hearing preservation. Overall facial nerve preservation was excellent with >90% achieving HB 1 to 3 function at final follow‐up.     

Vestibular impairment and cochlear implantation

Conclusion. Cochlear implantation (CI) may induce vestibular impairment soon after surgery as well as after implant activation. This impairment seems to be independent from the cause of deafness and can be considered a possible complication from the intra-operative trauma and, to minor degree, from the ongoing electric stimulation. It would also seem that vestibular damage occurs independently from the likelihood of post-operative hearing deterioration. In unilateral selected CI cases, vestibular examination can be proposed as additional pre-operative exam for selection of the ear to be implanted. Objectives. This study has been planned in order to get evidence of eventual impairment of the vestibular apparatus after cochlear implantation as well as to verify whether the impairment could be related to different variables, such as cause of deafness, concomitant hearing deterioration, surgical trauma and duration of electrical stimulation. Method. Charts from two different populations of implantees have been reviewed, 21 from a prospective, 72 from a retrospective study, respectively. All the patients were implanted with Clarion® devices of different generation. Vestibular testing was based on rotatory, caloric (when possible) and stabilometric measurements, which were carried out pre-operatively and at the following different times: 5 weeks after CI surgery, and 30, 60 and 90 days after CI activation. Hearing thresholds were also assessed in those patients who showed signs of vestibular impairment as well as in a group of patients without vestibular disorders (control). Patients belonging to the retrospective group were all asked to fill a questionnaire regarding their balance condition. Results. In 14.3% of the prospective study group, a grade I and II spontaneous nystagmus was evidenced pre-operatively and remained unchanged during the whole assessment period. A grade II spontaneous nystagmus was present in 3 patients (21.4%) of the same group after surgery. In the immediate post-operative period, vestibular impairment was displayed as true rotational vertigo in 21.4% and unsteadiness in 42.8% of the study group. Severe unsteadiness was present during the first 2 days after activation in 14.3% of the subjects. In 21.4% of the patients a VPPB episode occured. In the retrospective study group, 26.4% of the subjects referred pre-operative dizziness and 25 patients (34.7%) referred immediate post-operative vertigo episodes, which remained in a milder form after CI activation in 12% of them. The hearing threshold showed to deteriorate in both vestibular-impaired and control CI population without significant difference.     

Vestibular schwannoma growth rates in neurofibromatosis type 2 natural history consortium subjects.

OBJECTIVE: To determine the amount of growth in vestibular schwannomas in Neurofibromatosis type 2 (NF2) patients from diagnosis through short-term (up to 2 yr) and long-term (up to 4 yr) follow-up. STUDY DESIGN: Retrospective magnetic resonance imaging (MRI) films were obtained on subjects enrolled in the NF2 Natural History study and examined for changes in vestibular schwannoma size over time. SETTING: Data were collected from nine foreign and domestic NF2 centers, including hospital-based, academic, and tertiary care centers. SUBJECTS: NF2 patients with MRI data and at least one follow-up examination within 9 months to 2 years of diagnosis were included; n=56 patients with 84 lesions for evaluation of growth. INTERVENTION: Routine, clinically obtained, magnetic resonance images were digitized and measured using image management software. Short-term follow-up was defined as up to 2 years (n=84 lesions), and long-term follow-up was defined as 3 to 4 years (n=29 lesions). OUTCOME MEASURES: Vestibular schwannoma size was assessed using anterior-posterior, medial-lateral, and greatest diameter linear measurements. RESULTS: Vestibular schwannomas increased in size (at least 5 mm) in 8% of the vestibular schwannomas across short-term follow-up. At long-term follow-up, 13% of the tumors had increased in size. On average, schwannomas increased in greatest diameter 1.3 mm per year across short-term follow-up. CONCLUSION: Slightly greater than 1 in 10 diagnosed NF2-related vestibular schwannomas increased in size by at least 5 mm by 4 years of follow-up, if still untreated at that time.