Long-term Quality of Life Following Vestibular Schwannoma Excision Via the Translabyrinthine Approach.

OBJECTIVE: To assess postoperative quality of life (QOL) and other patient-reported outcomes following surgery for vestibular schwannoma. STUDY DESIGN: Cross-sectional retrospective case review using postal questionnaires. SETTING: Tertiary referral center. PATIENTS: Five hundred consecutive patients undergoing surgery for vestibular schwannoma. INTERVENTION(S): Patients undergoing surgery via the translabyrinthine approach (excluding neurofibromatosis type 2) under the senior author, with a minimum of 5 years follow-up, were included. MAIN OUTCOME MEASURE(S): QOL was assessed using the Short Form 36 (SF-36) questionnaire and a disease-specific survey to assess patients' subjective outcomes. RESULTS: The SF-36 scores in this group were significantly lower than the general UK population, though 24% of respondents reported a subjective improvement in overall QOL. Tumors larger than 4 cm were related to a reduced SF-36 total mental component score (p = 0.037). Increased age at time of surgery correlated with a reduced physical component of QOL (correlation coefficient = -0.26) and an improved mental component (correlation coefficient = 0.26). Subjective reports of postoperative symptoms and return to work, driving and social activities were similar to other published studies. 35% of patients reported vivid dreams or nightmares following surgery; the first reported incidence of this phenomenon in a large group of vestibular schwannoma patients. CONCLUSIONS: Generic measures of QOL in patients following translabyrinthine surgery for vestibular schwannoma do not always match subjective reports, reflecting the complexity of QOL assessment and the range of outcomes in this group. Increased time since surgery appears to be associated with an improvement in mental health.

Cochlear implantation in adolescents: Factors influencing compliance.

OBJECTIVES: To quantify rates of non- and partial-use of cochlear implants (CIs) in adolescent patients implanted in adolescence and childhood and identify factors influencing compliance. METHODS: A retrospective case note review undertaken at The Manchester Auditory Implant Centre. Adolescents were defined as young people aged 11-18 years. Individuals implanted in adolescence were defined as Group 1, individuals implanted in childhood under the age of 3 years and currently adolescents were defined as Group 2 and individuals implanted between the age of 3 and11 years and currently adolescents were defined as Group 3. Non-use was defined as not using the CI at all and partial use was defined as consistently using the CI less than full-time, or fluctuating periods of full and less than full-time use. RESULTS: In Group 1 there was 1 non-user (1.3%) and 11 partial-users (13.9%), with an overall non-compliance rate of 15.2%. In Group 2 there was one non-user (1.9%) and one partial-user (1.9%) with an overall non-compliance rate of 3.8%. In Group 3 there were no non-users and eight partial-users (9%), with an overall non-compliance rate of 9%. The factors influencing compliance differed between groups with the most common factor in Group 1 being a preference for the auditory input gained from the contralateral hearing aid (50%). In Groups 2 and 3 the main factors influencing compliance were behavioural and related to wearing the implant only at school (50 and 75%, respectively). CONCLUSIONS: Patients implanted during adolescence have higher rates of non- and partial-use compared with their adolescent counterparts who have been implanted during childhood. It is important to investigate factors influencing non-compliance so appropriate support may be provided to the patient and their family.

Surgical outcomes in cystic vestibular schwannoma versus solid vestibular schwannoma.

OBJECTIVE: To review the postoperative surgical outcomes of cystic vestibular schwannomas (CVSs), especially facial nerve outcomes, and compare these results with those from matched solid vestibular schwannomas (SVS) resected during the same period at a tertiary referral center. STUDY DESIGN: Retrospective case series. METHODS: One hundred thirty-one surgically managed patients with cystic vestibular schwannomas (CVSs) were age, sex, and tumor size matched to 131 surgically managed patients with solid vestibular schwannomas (SVSs). Demographics, tumor morphology, surgical approach, extent of resection, facial and nonfacial complications, and recurrence rates were compared between the 2 groups. Subtotal removal was defined as removal of at least 95% of the tumor. RESULTS: The mean maximal tumor diameter was 2.8 cm for both groups. For CVS, gross total tumor resection (GTR) was achieved in 92 patients (70.2%), and subtotal tumor resection (STR) was achieved in 39 patients (29.8%). Postoperative facial nerve outcomes at 1-year follow-up were good (HB Grade I-III) in 116 (88.5%) of 131 CVS patients. Twenty-three patients developed nonfacial nerve-related complications (17.6%). For SVS, GTR was achieved in 102 patients (77.9%), and STR was achieved in 29 patients (22.1%). Postoperative facial nerve outcomes at 1-year follow-up were good (HB Grade I-III) in 118 (90.1%) of 131 SVS patients. Nonfacial nerve related complications occurred in 14 patients (10.7%). None of the differences in outcome between the 2 groups were statistically significant. CONCLUSION: The difference in surgical outcomes is minimal between patients with CVS and those with SVS, not reaching statistical significance. We think, with judicious surgical management, similar outcomes can be achieved in cystic tumors and solid tumors.

Cochlear implantation in children with syndromic deafness.

OBJECTIVE: To examine the outcome of cochlear implantation in children with syndromic deafness, who are increasingly being considered for cochlear implants and who represent a unique challenge to the cochlear implant team. METHOD: In this retrospective case series in a tertiary referral cochlear implant centre, we describe a series of 38 children with a clinical syndrome causing deafness who have undergone cochlear implantation. The outcome measures are Bench-Kowal-Bamford (BKB) speech reception score (range 0-100%) and speech perception ability using the Geers and Moog Speech Reception Score (SRS) (range from 0; no speech perception, to 6; open set recognition of words). RESULTS: The syndromes identified were Waardenburg syndrome (n = 10), Usher syndrome (n = 9), Pendred syndrome (n = 7), Jervell and Lange-Nielsen syndrome (n = 5), CHARGE syndrome (n = 2), and 1 each of Stickler, CINCA (Chronic Infantile Neurological Cutaneous and Articular), Bartter, Down, and Donnai-Barrow syndromes. After a minimum of 19 months following implantation, BKB was measurable in 20 of 38 patients, and ranged from 46 to 100% in quiet (median 87%, mean 81%). Eighteen children (55%) achieved a SRS at level six, and a further 8 (24%) achieved level five. There was significant variation of outcome between and within syndrome groups. CONCLUSIONS: Additional disabilities are frequently encountered when considering children for cochlear implantation, and may be part of a recognised syndrome. Outcome is often excellent but can be variable even within the same syndrome group, and such children are therefore assessed on an individual basis to ensure a realistic expectation.

History of cochlear implantation.

The evolution of cochlear implantation from early experimentation with electrical stimulation of the ear in the 18th century to the sophisticated multichannel device that we now routinely implant has been remarkable. It is a tribute to the perseverance of a number of dedicated scientists in many disciplines who, in the face of serious, but ultimately unfounded, theoretical objections and ethical challenges, were eventually able to restore useful hearing to that large group of profoundly deaf adults and children, who were hitherto untreatable. The transformation in the lives of prelingually deaf children, who are now able to acquire speech and language and fulfil their full educational potential has been particularly spectacular. Cochlear implantation is the greatest advance in the field of otolaryngology in the last hundred years, and in medicine in general is one of the landmark achievements of the 20th century.

Cochlear implantation in children with Jervell and Lange-Nielsen syndrome - a cautionary tale.

OBJECTIVE AND IMPORTANCE: Jervell and Lange-Nielsen (JLN) syndrome is a rare cause of congenital profound hearing loss associated with a prolonged QT interval on the electrocardiogram. Children presenting for cochlear implantation with this condition may be asymptomatic but are at risk of sudden death. SCREENING AND SUBSEQUENT: careful management is therefore required to ensure a successful outcome. We present our experience of cochlear implantation in children with JLN syndrome, including two who died unexpectedly, and suggest a protocol for management of such cases. Clinical presentation Four cases of cochlear implantation in JLN syndrome are described. None had any previous cardiological family history. Two were diagnosed pre-operatively but, despite appropriate management under a cardiologist, died from cardiac arrest; the first in the perioperative period following reimplantation for infection, and the second unrelated to his cochlear implant surgery. The other two patients were diagnosed only subsequent to their implantation and continue to use their implants successfully. CONCLUSION: These cases highlight the variation in presentation of JLN syndrome, and the spectrum of disease severity that exists. Our protocol stresses the importance of careful assessment and counselling of parents by an experienced implant team.

Vestibular schwannomas occur in schwannomatosis and should not be considered an exclusion criterion for clinical diagnosis.

Schwannomatosis is a recently delineated inherited condition that has clinical overlap with neurofibromatosis type 2 (NF2). Diagnostic criteria have been developed to distinguish schwannomatosis from NF2, but the existence of mosaic NF2, which may closely mimic schwannomatosis, makes even these criteria problematic. In particular, it is not clear why there is a relative sparing of the cranial nerves from schwannomas in schwannomatosis. We have identified two individuals with schwannomatosis and a unilateral vestibular schwannoma (VS), where a diagnosis of NF2 has been excluded. A third case with an identified SMARCB1 mutation was reported by two radiologists to have a VS, but this was later confirmed as a jugular schwannoma. These cases question whether the current exclusion of a VS from the clinical diagnosis of schwannomatosis is justified.

Cochlear implantation in children with cerebral palsy.

OBJECTIVE: Few studies have looked at the outcomes of children with complex needs following cochlear implantation. Increasing evidence supports the case for implantation in these children. To date there is very little evidence available evaluating the role of cochlear implantation in children with cerebral palsy. In this paper we look at the Manchester Cochlear Implant Programme's experience of implantation in 36 children with cerebral palsy. METHODS: A retrospective review of prospectively collected data for all children with cerebral palsy was undertaken. Cognitive and physical disability was scored by members of the cochlear implant team. A modified version of Geers and Moogs 1987 Speech Reception Score was used to assess outcome. Data was analysed looking at the relationship between cognitive and physical impairment, age at implantation and the SRS outcomes. RESULTS: This study demonstrated that children with cerebral palsy and a mild cognitive impairment do significantly better following implantation than those with a severe impairment (p=0.008). Children with mild physical impairment did not appear to do significantly better than those with moderate or severe impairments (mild versus severe p=0.13). Age at implantation was not a significant prognostic factor in this study group. CONCLUSIONS: Children with complex needs are increasingly being referred for consideration of cochlear implantation. Further research is required to help guide candidacy, but each case must be considered individually. Higher functioning does appear to be the most important prognostic indicator regarding outcome but the effect of modest improvement in sound perception should not be underestimated.

Cochlear implantation in Donnai-Barrow syndrome.

OBJECTIVE AND IMPORTANCE: Donnai-Barrow syndrome is a rare autosomal recessive disorder associated with severe sensorineural hearing loss (SNHL). Several ocular abnormalities have also been described in this syndrome, including hypertelorism, down-slanting palpebral fissures, myopia and retinal detachment. The condition is also associated with diaphragmatic hernia, exomphalos, absent corpus callosum and developmental delay. We describe the first recorded case of cochlear implantation in this rare disorder. CLINICAL PRESENTATION: This case of Donnai-Barrow syndrome was identified from our paediatric cochlear implant database. A case-note review was performed identifying patient demographics, operative findings and surgical outcome. In addition, pre- and post-operative auditory and communication performance was analysed. INTERVENTION: The child initially received a right cochlear implant at 39 months of age, but unfortunately the device failed 4 years post-operatively. Subsequently, bilateral simultaneous cochlear implantation was performed. BKB scores were 98% for bilateral implant use when tested 2 years post-operatively. Individual testing revealed a score of 94% for the right ear alone, and 80% for the left. The child achieved a 100% score on sound localisation testing using 3 speakers. CONCLUSIONS: Donnai-Barrow syndrome is a rare cause of SNHL compounded by the potential for visual impairment. To our knowledge this is the first report of cochlear implantation to rehabilitate hearing loss in this condition.

Outcome of cochlear implantation in asymptomatic congenital cytomegalovirus deafened children.

OBJECTIVES/HYPOTHESIS: Congenital cytomegalovirus (cCMV) infection is a common cause of sensorineural hearing loss (SNHL). The incidence of SNHL is higher in symptomatic cCMV infants and is usually identified early. By contrast, the incidence of SNHL is lower in children with asymptomatic cCMV, and the hearing loss can be delayed in onset and progressive. The objective was to compare the outcome of cochlear implantation in children deafened by cCMV with a control group of children with implants who do not have the condition. STUDY DESIGN: Retrospective review of case notes and data base. METHODS: Retrospective review of 14 children with asymptomatic cCMV who underwent cochlear implantation. Their outcome measures were compared with those of a matched population by using standard assessment tools. RESULTS: In the study group, the Modified Categories of Auditory Performance (M-CAP) score (range, 1-7) ranged from 2 to 7 (mean, 4.2). In the control group, the M-CAP ranged from 5 to 7 (mean, 6.0). In the study group, the Manchester Spoken Language Development Scale (MSLDS) score (range, 1-10) ranged from 1 to 9 (mean, 5.4). In the control group, the MSLDS ranged from 3 to 10 (mean, 8.1). CONCLUSIONS: Children with asymptomatic deafness caused by cCMV benefit from cochlear implantation but perform less well than a comparable group of children with implants who do not have cCMV. There is a range of performance in the cCMV group that may relate to the degree of motor or cognitive disabilities.

Empirical development of improved diagnostic criteria for neurofibromatosis 2.

PURPOSE: Four sets of clinical diagnostic criteria have been proposed for neurofibromatosis 2, but all have low sensitivity at the time of initial clinical assessment for the disease among patients with a negative family history who do not present with bilateral vestibular schwannomas. We have empirically developed and tested an improved set of diagnostic criteria that uses current understanding of the natural history and genetic characteristics of neurofibromatosis 2 to increase sensitivity while maintaining very high specificity. METHODS: We used data from the UK Neurofibromatosis 2 Registry and Kaplan-Meier curves to estimate frequencies of clinical features at various ages among patients with or without unequivocal neurofibromatosis 2. On the basis of this analysis, we developed the Baser criteria, a new diagnostic system that incorporates genetic testing and gives more weight to the most characteristic features and to those that occur before 30 years of age. RESULTS: In an independent validation subset of patients with unequivocal neurofibromatosis 2, the Baser criteria increased diagnostic sensitivity to 79% (9-15% greater than previous sets of criteria) while maintaining 100% specificity at the age at onset of the first characteristic sign of neurofibromatosis 2. CONCLUSION: The Baser criteria permit early diagnosis in a greater proportion of patients with neurofibromatosis 2 than previous sets of diagnostic criteria.

Neurofibromatosis type 2.

Neurofibromatosis type 2 (NF2) is an autosomal-dominant inherited tumour predisposition syndrome caused by mutations in the NF2 gene on chromosome 22. Affected individuals develop schwannomas characteristically affecting both vestibular nerves leading to hearing loss and eventual deafness. Rehabilitation with brain stem implants and in some cases cochlear implants is improving this outcome. Schwannomas also occur on other cranial nerves, on spinal nerve roots and peripheral nerves. Meningiomas and ependymomas are other tumour features. In excess of 50% of patients represent de novo mutations and as many as 33% are mosaic for the underlying disease causing mutation. Truncating mutations (nonsense, frameshift insertions/deletions) are the most frequent germline events and cause the most severe disease, whilst single and multiple exon deletions are common and are usually associated with milder NF2. A strategy for detection of the latter is vital for a sensitive genetic analysis. NF2 represents a difficult management problem with most patients facing substantial morbidity and reduced life expectancy. Surgery remains the focus of current management although watchful waiting and occasionally radiation treatment have a role. We are seeing the advent of tailored drug therapies aimed at the genetic level and these are likely to provide huge improvements for this devastating, life limiting condition.

Cranial meningiomas in 411 neurofibromatosis type 2 (NF2) patients with proven gene mutations: clear positional effect of mutations, but absence of female severity effect on age at onset.

BACKGROUND: Meningiomas have been reported to occur in approximately 50% of neurofibromatosis type 2 (NF2) patients. The NF2 gene is commonly biallelically inactivated in both schwannomas and meningiomas. The spectrum of NF2 mutations consists mainly of truncating (nonsense and frameshift) mutations. A smaller number of patients have missense mutations, which are associated with a milder disease phenotype. METHODS: This study analysed the cumulative incidence and gender effects as well as the genotype-phenotype correlation between the position of the NF2 mutation and the occurrence of cranial meningiomas in a cohort of 411 NF2 patients with proven NF2 mutations. RESULTS AND CONCLUSION: Patients with mutations in exon 14 or 15 were least likely to develop meningiomas. Cumulative risk of cranial meningioma to age 50 years was 70% for exons 1-3, 81% for exons 4-6, 49% for exons 7-9, 56% for exons 10-13, and 28% for exons 14-15. In the cohort of 411 patients, no overall gender bias was found for occurrence of meningioma in NF2 disease. Cumulative incidence of meningioma was close to 80% by 70 years of age for both males and females, but incidence by age 20 years was slightly increased in males (male 25%, female 18%; p=0.023). Conversely, an increased risk of meningiomas in women with mosaic NF2 disease was also found.

Brain stem responses evoked by stimulation of the mature cochlear nucleus with an auditory brain stem implant.

OBJECTIVES: The Nucleus auditory brain stem implant (ABI) has been used in the hearing rehabilitation of totally deaf individuals for whom a cochlear implant is not an option such as in the case of neurofibromatosis type 2 (NF2). Intraoperative electrically evoked auditory brain stem responses (EABRs) are recorded to assist in the placement of the electrode array over the dorsal and ventral cochlear nuclei in the lateral recess of the IVth ventricle of the brain stem. This study had four objectives: (1) to characterize EABRs evoked by stimulation with an ABI in adolescents and adults with NF2, (2) to evaluate how the EABR morphology relates to auditory sensations elicited from stimulation by an ABI, (3) to establish whether there is evidence of morphology changes in the EABR with site of stimulation by the ABI, and (4) to investigate how the threshold of the EABR relates to behavioral threshold and comfortably loud sensations measured at initial device activation. DESIGN: Intraoperative EABRs were recorded from 34 subjects with ABIs: 19 male and 15 female, mean age 27 yrs (range 12 to 52 yrs). ABI stimulation was applied at seven different sites using either wide bipolar stimulation across the array or in subsections of the array from medial to lateral and inferior to superior. The EABRs were analyzed with respect to morphology, peak latency, and changes in these characteristics with the site of stimulation. In a subset of eight subjects, additional narrow bipolar sites were stimulated to compare the intraoperative EABR threshold levels with the behavioral threshold (T) and comfortably loud (C) levels of stimulation required at initial device activation. RESULTS: EABRs were elicited from 91% of subjects. Morphology varied from one to four vertex-positive peaks with mean latencies of 0.76, 1.53, 2.51, and 3.64 msecs, respectively. The presence of an EABR from stimulation by electrodes across the whole array had a high predictive value for the presence of auditory electrodes at initial device activation. When examining subsections of the array, the absence of an EABR was a poor predictor for the absence of auditory electrodes. The morphology of the EABRs varied with site of stimulation in 16 cases, but there was no consistent pattern of change with stimulation site. There was a trend for more auditory electrodes to be present in stimulation sites that evoked EABRs with a higher number of peaks in the waveform. The EABR threshold was closer to the behavioral C level than the T level, but there was no overall correlation between the intraoperative EABR threshold level and the behavioral T and C levels. CONCLUSIONS: The presence of an intraoperative EABR corresponded well to the presence of auditory electrodes. The absence of an EABR from stimulating subsections of the array was not; however, a good indicator for the absence of auditory electrodes and the EABR from such stimulation would not be of assistance in identifying the nonauditory sections of the array to exclude in behavioral fitting of the device. The morphology of the EABR did not relate to site of stimulation. More peaks in the EABR was associated with a greater number of electrodes with auditory sensations, suggesting that correct positioning of the ABI activated more auditory subsystems within the cochlear nucleus. The intraoperative EABR thresholds did not correlate with the behavioral T and C levels and could not be used to assist in device fitting.

Brain stem responses evoked by stimulation with an auditory brain stem implant in children with cochlear nerve aplasia or hypoplasia.

OBJECTIVES: The inclusion criteria for an auditory brain stem implant (ABI) have been extended beyond the traditional, postlingually deafened adult with Neurofibromatosis type 2, to include children who are born deaf due to cochlear nerve aplasia or hypoplasia and for whom a cochlear implant is not an option. Fitting the ABI for these new candidates presents a challenge, and intraoperative electrically evoked auditory brain stem responses (EABRs) may assist in the surgical placement of the electrode array over the dorsal and ventral cochlear nucleus in the brain stem and in the postoperative programming of the device. This study had four objectives: (1) to characterize the EABR by stimulation of the cochlear nucleus in children, (2) to establish whether there are any changes between the EABR recorded intraoperatively and again just before initial behavioral testing with the device, (3) to establish whether there is evidence of morphology changes in the EABR depending on the site of stimulation with the ABI, and (4) to investigate how the EABR relates to behavioral measurements and the presence of auditory and nonauditory sensations perceived with the ABI at initial device activation. DESIGN: Intra- and postoperative EABRs were recorded from six congenitally deaf children with ABIs, four boys and two girls, mean age 4.2 yrs (range 3.2 to 5.0 yrs). The ABI was stimulated at nine different bipolar sites on the array, and the EABRs recorded were analyzed with respect to the morphology and peak latency with site of stimulation for each recording session. The relationship between the EABR waveforms and the presence or absence of auditory electrodes at initial device activation was investigated. The EABR threshold levels were compared with the behavioral threshold (T) and comfortably loud (C) levels of stimulation required at initial device activation. RESULTS: EABRs were elicited from all children on both test occasions. Responses contained a possible combination of one to three peaks from a total of four identifiable peaks with mean latencies of 1.04, 1.81, 2.61, and 3.58 msecs, respectively. The presence of an EABR was a good predictor of an auditory response; however, the absence of the EABR was poor at predicting a site with no auditory response. The morphology of EABRs often varied with site of stimulation and between EABR test occasions. Postoperatively, there was a trend for P1, P3, and P4 to be present at the lateral end of the array and P2 at the medial end of the array. Behavioral T and C levels showed a good correlation with postoperative EABR thresholds but a poor correlation with intraoperative EABR thresholds. CONCLUSIONS: The presence of an intraoperative EABR was a good indicator for the location of electrodes on the ABI array that provided auditory sensations. The morphology of the EABR was often variable within and between test sessions. The postoperative EABR thresholds did correlate with the behavioral T and C levels and could be used to assist with initial device fitting.

Outcome from surgery for vestibular schwannomas in children.

OBJECT: A review of sporadic and NF2-related vestibular schwannoma surgery in children (under 18 years of age) with a specific interest in resection rates, recurrence, facial nerve outcomes, hearing preservation, hearing rehabilitation and genetic analysis. METHODS: A retrospective analysis of prospectively collected data of 35 consecutively operated vestibular schwannomas in 29 paediatric patients that underwent 38 operations between 1992 and 2007. Pre- and post-operative radiology, facial nerve function, pure tone audiogram and speech discrimination tests were performed with a mean follow-up of 4.5 years. Tumour and blood mutations were analysed in 86% of patients. RESULTS: Total resection was achieved in all sporadic cases and 68% of NF2 cases. Near total resection led to tumour recurrence in 5 out of 10 cases. The facial nerve was anatomically preserved in 92%. Facial nerve function was excellent to good (Grades 1-3) in 88% with outcome related to tumour size. Hearing preservation was successful in 3 of 11 cases. CONCLUSIONS: Surgery with complete resection results in excellent tumour control, but it is more difficult to attain total resection in NF2 with a relatively high recurrence rate of persistently growing tumours. A better facial outcome is associated with smaller tumours, near-total resection and first time surgery. Hearing preservation is possible in a minority. Hearing rehabilitation can be successful by utilising cochlear implants and auditory brain stem implants (ABI) as appropriate. Overall there is a low complication rate and results are comparable with adult series.

Neural plasticity in blind cochlear implant users.

This study, using positron emission tomography, investigates the cortical activation generated by auditory stimulation in two congenitally blind cochlear implant users. In the patient with a relatively short history of deafness, activity increased in both auditory cortices and fell in the visual cortices. The patient with a longer period of deafness had greater activation of the visual cortices than the auditory cortices. A similar pattern of activity was seen when this patient subsequently had a second cochlear implant inserted into the opposite ear. The neural pathways formed after the restoration of auditory input in the congenitally blind can activate either the auditory or visual cortices. We suggest that the visual cortical activation demonstrated is of functional significance.

What are the implications in individuals with unilateral vestibular schwannoma and other neurogenic tumors?

OBJECTIVES: Individuals who develop a unilateral vestibular schwannoma (VS) and other neurogenic tumors are at high risk of having the inherited condition neurofibromatosis Type 2 (NF2). The risk of bilateral disease and transmission risk to offspring are important in surgical planning and counseling. The authors have attempted to resolve these risks. METHODS: A large NF2 dataset was interrogated for individuals who had initially presented with a unilateral VS and other tumors before developing bilateral disease, to assess the contralateral and offspring risks. RESULTS: Ninety-six patients with a unilateral VS and additional neurogenic tumors had a bilaterality rate of 48% at 20 years in those initially diagnosed when > 18 years of age and 82% if presenting earlier. Constitutional NF2 mutations were found in blood in 25 (27%) of 92, but 13 (76%) of 17 patients presenting with unilateral VS at < or = 18 years of age. Tumor analysis suggests that the vast majority of the remainder are mosaic for an NF2 mutation. CONCLUSIONS: Patients with unilateral VS and other NF2-related tumors who fulfill Manchester criteria have a high risk of developing a contralateral tumor, especially if presenting in childhood. Transmission risks are reduced for offspring, particularly in the older patients who are likely to be mosaic.