Type 2 neurofibromatosis: the need for supraregional care?

Characteristics and Outcomes of Pediatric Vestibular Schwannomas

OBJECTIVE

To review the demographics, treatment modalities, and survival of children with vestibular schwannomas.

STUDY DESIGN

Analysis using the Surveillance, Epidemiology, and End Results (SEER) database.

SUBJECTS AND METHODS

Pediatric patients from birth to 18 years in the SEER database were included from 2004 to 2014 based on a diagnosis of vestibular schwannoma using the primary site International Classification of Diseases (ICD) O-3 code of C72.4: acoustic nerve and the ICD O-3 histology codes of 9540/1: neurofibromatosis, Not Otherwise Specified (NOS); 9560/0: neurilemoma, NOS; or 9570/0: neuroma, NOS.

RESULTS

One hundred forty-eight pediatric vestibular schwannomas (VSs) cases were identified. The mean age at diagnosis was 13.9 years (range, 4.0-18.0). Eighty-five (57.4%) patients were women. Seventy-seven (52.0%) patients had isolated unilateral VSs while 71 (48.0%) patients had either bilateral VSs or unilateral VSs with other brain, spinal cord, or cranial nerve tumors. Eighty two (55.4%) patients received surgical resection only, 45 (30.4%) received no treatment, 6 (4.1%) received radiation only, and 12 (8.1%) received surgery and radiation. The median tumor size for patients who received no treatment was 9.5 mm (interquartile range [IQR]: 8.0) compared with 33.5 mm (IQR: 23.0) for patients who received surgical care and 41.0 mm (IQR: 1.5) for patients who received both surgery and radiation (p < 0.001). The 5-year overall survival rate was 97%.

CONCLUSION

Pediatric VSs tend to be diagnosed in adolescence. No men or women predominance was appreciated. Treatment varied according to tumor size. Survival rates for children with vestibular schwannomas are excellent. These data may assist healthcare providers when counseling children with vestibular schwannomas and their families.

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.

Clinical and molecular predictors of mortality in neurofibromatosis 2: a UK national analysis of 1192 patients

BACKGROUND

Neurofibromatosis 2 (NF2) is an autosomal-dominant tumour predisposition syndrome characterised by bilateral vestibular schwannomas, considerable morbidity and reduced life expectancy. Although genotype-phenotype correlations are well established in NF2, little is known about effects of mutation type or location within the gene on mortality. Improvements in NF2 diagnosis and management have occurred, but their effect on patient survival is unknown.

METHODS

We evaluated clinical and molecular predictors of mortality in 1192 patients (771 with known causal mutations) identified through the UK National NF2 Registry. Kaplan-Meier survival and Cox regression analyses were used to evaluate predictors of mortality, with jackknife adjustment of parameter SEs to account for the strong intrafamilial phenotypic correlations that occur in NF2.

RESULTS

The study included 241 deaths during 10 995 patient-years of follow-up since diagnosis. Early age at diagnosis and the presence of intracranial meningiomas were associated with increased mortality, and having a mosaic, rather than non-mosaic, NF2 mutation was associated with reduced mortality. Patients with splice-site or missense mutations had lower mortality than patients with truncating mutations (OR 0.459, 95% CI 0.213 to 0.990, and OR 0.196, 95% CI 0.213 to 0.990, respectively). Patients with splice-site mutations in exons 6-15 had lower mortality than patients with splice-site mutations in exons 1-5 (OR 0.333, 95% CI 0.129 to 0.858). The mortality of patients with NF2 diagnosed in more recent decades was lower than that of patients diagnosed earlier.

CONCLUSIONS

Continuing advances in molecular diagnosis, imaging and treatment of NF2-associated tumours offer hope for even better survival in the future.

Neurofibromatosis type 2

Type 2 neurofibromatosis (NF2) is an autosomal dominant disorder caused by mutations in the NF2 tumor suppressor gene NF2 on chromosome 22. Around 1 in 33000 people are born with an NF2 mutation although more than one-third of the 60% of de novo cases are not conceived with the mutation but this develops later in embryogenesis (mosaics). NF2 has a substantial effect on life expectancy and individuals with a constitutional truncating mutation have the worst prognosis. The vast majority of people with NF2 will develop bilateral vestibular schwannomas with many developing schwannomas on other cranial, spinal and peripheral nerves. Cranial and spinal meningiomas and intraspinal low grade indolent ependymomas are the other major tumor features. Cutaneous features can be subtle with only 70% having evidence of intracutaneous plaque-like schwannomas or subcutaneous lesions on peripheral nerves. Café-au-lait patches are more frequent than in the general population but in only around 1% will meet NIH criteria for NF1.

[Neurofibromatoses]

Neurofibromatosis type 1 (NF1) and type 2 (NF2) are hereditary autosomal dominant neurocutaneous disorders, the phacomatoses, characterized by the development of tumors derived from the cells of the peripheral nerve sheath and also includes schwannomatosis. Regarding the clinical and genetic aspects they are, however, two distinct entities which are described separately in the following review. In addition to the typical clinical presentation and diagnostic criteria, characteristic imaging findings are presented especially in terms of the role of imaging in the diagnosis, follow-up and assessment of prognostic aspects in these multisystemic disorders.

Factors associated with symptom-specific psychological and functional impact among acoustic neuroma patients

INTRODUCTION

The main purpose of this study was to investigate the psychological and functional impact attributed to acoustic neuroma symptoms.

MATERIALS AND METHODS

A sample of 207 acoustic neuroma patients completed a study-specific questionnaire about the severity, frequency, and psychological and functional impact of 9 acoustic neuroma symptoms.

RESULTS

The survey response rate was 56.4 per cent. All symptoms had some degree of psychological impact for the majority of participants; hearing loss was the symptom most often reported to have a severe psychological impact. The majority of respondents reported functional impact attributed to hearing loss, balance disturbance, dizziness, eye problems, headache and fatigue; balance disturbance was the symptom most often reported to have a severe functional impact. For most symptoms, psychological and functional impact were related to severity and frequency.

CONCLUSION

Of the acoustic neuroma symptoms investigated, hearing loss and balance disturbance were the most likely to have a severe psychological and functional impact, respectively.

Prognostic value and management of spinal tumors in neurofibromatosis type 2 patients

PURPOSE

Neurofibromatosis type 2 (NF2) is a well-studied disease. Although spinal tumors are frequent, many issues concerning their prognosis and management still have to be clarified. The authors studied the clinical impact and radiological progression of spinal tumors in patients with NF2 to determine their prognostic value.

METHODS

A total of 80 NF2 patients were followed in the Lille University Hospital between 1987 and 2011. Clinical, radiological and genetic data were retrospectively recorded and analyzed. Patients underwent annual cranial and spinal MRI. Both the location and size of each tumor were reported. The diagnosis of NF2 was confirmed either because the patient met the Manchester criteria or by the presence of genetic mutation.

RESULTS

The mean follow-up period was 8.8 years (range 1 to 24 years; SD: ±0.8), and the mean age at diagnosis was 27.2 years (range 6 to 73 years; SD: ±1.7). Among all patients, 48 harbored spinal tumors. Twenty of them were symptomatic, and 21 were operated on. Patients with spinal tumors had a lower age at diagnosis (p = 0.02), a higher number of intracranial meningiomas (p = 0.028) and schwannomas (p = 0.03), and more nonsense and frameshift mutations (p = 0.04).

CONCLUSION

Spinal tumors are common in NF2, and all patients should be regularly monitored by spinal MRI. The presence of spinal tumors seems to be a factor indicating poor prognosis. Clinical and radiological monitoring of spinal tumors could lead to early treatment both when clinical symptoms are present and in case of proven radiological evolution, maintaining a favorable functional prognosis as long as possible.

Outcome of translabyrinthine surgery for vestibular schwannoma in neurofibromatosis type 2

OBJECTIVES

To analyse the long-term outcome of translabyrinthine surgery for vestibular schwannoma (VS) in neurofibromatosis type 2 (NF2). RESEARCH TYPE: Retrospective cohort study.

SETTING

Two tertiary referral NF2 units.

PATIENTS

One hundred and forty eight translabyrinthine operations for patients with VS were performed. Preoperative stereotactic radiotherapy had been performed on 12(9.4%) patients.

RESULTS

Mean tumour size was 3.1 cm. Total tumour excision was achieved in 66% of cases, capsular remnants were left in 24% of cases, and subtotal excision was achieved in 5% and partial removal was achieved in 5%. The radiological residual/recurrence rate was 13.9%. The perioperative mortality was 1.6%. At 2 years postoperatively, facial function was expressed in terms of House-Brackmann score (HB): HB 1 in 53.4%, HB 1/2 in 61.3%, HB 1-3 in 83.2% and HB 4-6 in 16.8%. All nine patients who underwent surgery following failed stereotactic radiotherapy had HB 3 function or better. Among 9.5% of the cases, 14 facial nerves were lost during surgery and repaired using direct anastomosis or grafting. There was no tinnitus present preoperatively in 27% of the cases, and 22% of patients developed tinnitus postoperatively. In patients with preoperative tinnitus, 61% remained the same, 17% got it resolved and only in 21% it worsened. The preoperative hydrocephalus rate was 26%, and among 15% of the cases five ventriculo-peritoneal (VP) shunts were performed. The cerebrospinal fluid leak rate was 2.5%. Fifty-six patients underwent auditory brainstem implantation (ABI) and two patients had cochlear implant (CI) sleepers inserted.

CONCLUSIONS

The management of patients with NF2 presents the clinician with a formidable challenge with many patients still presenting themselves late with the neurological compromise and a large tumour load. There is still an argument for the management by observation until the neurological compromise dictates interventional treatment particularly with the option of hearing rehabilitation with ABI or CI. The translabyrinthine approach provides a very satisfactory means of reducing the overall tumour volume.

Neurofibromatose Typ 2

Neurofibromatose Typ 2 (NF2) ist eine genetische Erkrankung, die autosomal-dominant vererbt wird und durch multiple Tumoren des Nervensystems gekennzeichnet ist. Bilaterale vestibuläre Schwannome, bekannt als Akustikusneurinome, sind das Hauptmerkmal der Erkrankung und treten bei etwa 90% der Betroffenen auf. Sie beeinträchtigen das Hörvermögen der Patienten und führen nicht selten zur Ertaubung. Ebenso häufig (>90%) treten bei NF2 spinale Tumoren (Schwannome, Meningiome und Ependymome) auf, die in etwa 1/3 der Fälle zu neurologischen Defiziten führen. Daneben finden sich zerebrale Schwannome und Meningiome als typische NF2-assoziierte Tumormanifestationen. Ferner kennzeichnen Polyneuropathie und okuläre Abnormalitäten das Krankheitsbild. Die genetische Ursache der NF2 ist eine heterozygote Inaktivierung des NF2-Tumorsuppressorgens, welches auf Chromosom 22q lokalisiert ist. Die Inzidenz der NF2 beträgt etwa 1:25.000 Geburten, wobei 50–80% der Patienten keine familiäre Belastung aufweisen. Bei Patienten mit Neumutationen (de novo) wurde eine Mosaikbildung mit überraschend hoher Frequenz (25–30%) nachgewiesen. Der vorliegende Beitrag beschreibt Klinik und Genetik der NF2 sowie aktuelle Entwicklungen in der medikamentösen Therapie.

Sporadic unilateral vestibular schwannoma in the pediatric population. Clinical article

OBJECT

Vestibular schwannomas (VSs) are rare in the pediatric population. Most often, these lesions manifest as a bilateral disease process in the setting of neurofibromatosis Type 2. Even in the absence of additional clinical diagnostic criteria, the presentation of a unilateral VS in a young patient may be a harbinger of future penetrance for this hereditary tumor syndrome.

METHODS

The authors retrospectively reviewed the charts of a cohort of 7 patients who presented with apparently sporadic, unilateral VSs. These patients had previously undergone surgery via translabyrinthine, retrosigmoid, or combined approaches. Clinical outcomes were reviewed with emphasis on facial nerve function and follow-up for signs and symptoms of a heritable disorder.

RESULTS

All patients underwent microsurgical resection in a multidisciplinary effort by the senior authors. The average tumor size was 4.57 cm, with an average duration of symptoms prior to definitive diagnosis of 31.2 months. The tumor size at the time of presentation followed a trend different from reports in adults, while the duration of symptoms did not. At a follow-up average of 6.3 years (range 1-12 years), 100% of patients demonstrated good facial function (House-Brackmann Grade I or II). No patient in this cohort demonstrated symptoms, objective signs, or genetic analysis indicating the presence of neurofibromatosis Type 2.

CONCLUSIONS

Diagnosis and management of sporadic, unilateral VSs in children is complicated by clinical presentations and surgical challenges unique from their adult counterparts. Careful consideration should be given to a heritable genetic basis for sporadic unilateral VS in the pediatric population. Results of genetic testing do not preclude the necessity for long-term follow-up and systemic investigation. In patients who present with large tumors, preliminary experience leads the authors to suggest that a combined retrosigmoid-translabyrinthine approach offers the greatest opportunity for preservation of facial nerve function.

Neurofibromatosis type 2 (NF2): a clinical and molecular review

Neurofibromatosis type 2 (NF2) is a tumour-prone disorder characterised by the development of multiple schwannomas and meningiomas. Prevalence (initially estimated at 1: 200,000) is around 1 in 60,000. Affected individuals inevitably develop schwannomas, typically affecting both vestibular nerves and leading to hearing loss and deafness. The majority of patients present with hearing loss, which is usually unilateral at onset and may be accompanied or preceded by tinnitus. Vestibular schwannomas may also cause dizziness or imbalance as a first symptom. Nausea, vomiting or true vertigo are rare symptoms, except in late-stage disease. The other main tumours are schwannomas of the other cranial, spinal and peripheral nerves; meningiomas both intracranial (including optic nerve meningiomas) and intraspinal, and some low-grade central nervous system malignancies (ependymomas). Ophthalmic features are also prominent and include reduced visual acuity and cataract. About 70% of NF2 patients have skin tumours (intracutaneous plaque-like lesions or more deep-seated subcutaneous nodular tumours). Neurofibromatosis type 2 is a dominantly inherited tumour predisposition syndrome caused by mutations in the NF2 gene on chromosome 22. More than 50% of patients represent new mutations and as many as one-third are mosaic for the underlying disease-causing mutation. Although truncating mutations (nonsense and frameshifts) are the most frequent germline event and cause the most severe disease, single and multiple exon deletions are common. A strategy for detection of the latter is vital for a sensitive analysis. Diagnosis is based on clinical and neuroimaging studies. Presymptomatic genetic testing is an integral part of the management of NF2 families. Prenatal diagnosis and pre-implantation genetic diagnosis is possible. The main differential diagnosis of NF2 is schwannomatosis. 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 with careful surveillance and occasionally radiation treatment have a role. Prognosis is adversely affected by early age at onset, a higher number of meningiomas and having a truncating mutation. In the future, the development of tailored drug therapies aimed at the genetic level are likely to provide huge improvements for this devastating condition.

Neurofibromatosis type 2 (NF2): a clinical and molecular review

Neurofibromatosis type 2 (NF2) is a tumour-prone disorder characterised by the development of multiple schwannomas and meningiomas. Prevalence (initially estimated at 1: 200,000) is around 1 in 60,000. Affected individuals inevitably develop schwannomas, typically affecting both vestibular nerves and leading to hearing loss and deafness. The majority of patients present with hearing loss, which is usually unilateral at onset and may be accompanied or preceded by tinnitus. Vestibular schwannomas may also cause dizziness or imbalance as a first symptom. Nausea, vomiting or true vertigo are rare symptoms, except in late-stage disease. The other main tumours are schwannomas of the other cranial, spinal and peripheral nerves; meningiomas both intracranial (including optic nerve meningiomas) and intraspinal, and some low-grade central nervous system malignancies (ependymomas). Ophthalmic features are also prominent and include reduced visual acuity and cataract. About 70% of NF2 patients have skin tumours (intracutaneous plaque-like lesions or more deep-seated subcutaneous nodular tumours). Neurofibromatosis type 2 is a dominantly inherited tumour predisposition syndrome caused by mutations in the NF2 gene on chromosome 22. More than 50% of patients represent new mutations and as many as one-third are mosaic for the underlying disease-causing mutation. Although truncating mutations (nonsense and frameshifts) are the most frequent germline event and cause the most severe disease, single and multiple exon deletions are common. A strategy for detection of the latter is vital for a sensitive analysis. Diagnosis is based on clinical and neuroimaging studies. Presymptomatic genetic testing is an integral part of the management of NF2 families. Prenatal diagnosis and pre-implantation genetic diagnosis is possible. The main differential diagnosis of NF2 is schwannomatosis. 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 with careful surveillance and occasionally radiation treatment have a role. Prognosis is adversely affected by early age at onset, a higher number of meningiomas and having a truncating mutation. In the future, the development of tailored drug therapies aimed at the genetic level are likely to provide huge improvements for this devastating condition.

Motor neuron regeneration through end-to-side repairs is a function of donor nerve axotomy

BACKGROUND

Over the past decade, a growing body of literature has emerged supporting the use of end-to-side (terminolateral) neurorrhaphy for the treatment of selected peripheral nerve injuries. It remains unclear, however, whether injury to the donor nerve is necessary to achieve significant regeneration through such repairs.

METHODS

End-to-side repair was studied in a rodent model in which the terminal limb of a transected peroneal nerve was sutured to the lateral aspect of the tibial nerve. Twenty-eight Lewis rats were randomized to four groups of seven animals each corresponding to incrementally greater donor nerve injuries as follows: group 1, conventional end-to-side neurorrhaphy; group 2, end-to-side neurorrhaphy with proximal crush injury; group 3, end-to-side neurorrhaphy with neurotomy; and group 4, end-to-end repair of transected peroneal nerve (positive control).

RESULTS

At 12 weeks, retrograde labeling of cell bodies of the ventral horn demonstrated significant differences between experimental groups, with mean counts in group 4 (1237 +/- 171) > group 3 (522 +/- 204) > group 2 (210 +/- 132) > or = group 1 (126 +/- 146). This association between nerve injury and motor neuron counts was closely mirrored in quantitative assessments of peripheral nerve regeneration and normalized wet muscle masses.

CONCLUSIONS

These data support the hypothesis that donor nerve injury is a prerequisite for significant motor neuronal regeneration across end-to-side repairs. Motor neuron regeneration through end-to-side repairs is optimized by deliberate transection of donor nerve axons.

A clinical, genetic and audiological study of patients and families with unilateral vestibular schwannomas. I. Clinical features of neurofibromatosis in patients with unilateral vestibular schwannomas

Ninety-three patients with unilateral vestibular schwannomas were examined in a clinical, genetic and audiological study, to determine whether they had features associated with neurofibromatosis Type 1 or neurofibromatosis Type 2. In 91 families, one patient only was found to be affected with a unilateral vestibular schwannoma. Patients did have a few café-au-lait macules, but fewer than six in number. None of the patients satisfied the cutaneous diagnostic criteria for neurofibromatosis Type 1. Neither Lisch nodules nor presenile posterior subcapsular lenticular opacities or cortical opacities were a feature. Five patients with unilateral vestibular schwannomas are described where the clinical findings raised the possibility of neurofibromatosis Type 2. It is suggested that certain individuals with unilateral vestibular schwannomas are at risk of developing neurofibromatosis Type 2. Furthermore, the possibility of neurofibromatosis Type 2 should be considered if more than one individual in a family is found to be affected with a unilateral vestibular schwannoma.

Spinal tumors in neurofibromatosis type 2. Is emerging knowledge of genotype predictive of natural history?

OBJECT

The authors conducted a study to examine the incidence, classification, and progression of spinal tumors in patients with neurofibromatosis Type 2 (NF2) treated at a single center, and to examine relationships with the known mutational subtypes of NF2.

METHODS

They performed a retrospective review of clinical records, neuroimaging studies, and genetic data obtained in 61 patients with NF2. Forty-one (67%) of 61 patients harbored one or more spinal tumors. Thirty-four patients had undergone serial spinal magnetic resonance imaging during a mean follow-up period of 52 months (range 10-103 months; median 53 months). In 16 patients there were multiple extramedullary tumors smaller than 5 mm, which did not progress. Fourteen patients harbored at least one extramedullary tumor that was greater than 5 mm; of these, radiological progression was demonstrated or spinal tumor excision was performed during the follow-up period in eight cases (57%). Eleven patients harbored intramedullary cord tumors in addition to small and large extramedullary tumors, three (27%) of which exhibited radiological progression. In cases in which genotypes were known, protein-truncating mutations were significantly more likely to be associated with the presence of spinal tumors than in other types (p = 0.03, Fisher exact test). No associations between clinical behavior of spinal tumors and genotype, however, could be demonstrated.

CONCLUSIONS

Spinal tumors in cases involving NF2 are heterogeneous in type, distribution, and behavior but larger-size tumors are more likely to progress significantly. Intramedullary tumors usually accompany multiple extramedullary tumors. In the authors' experience subtyping of the NF2 mutation has not yet influenced management. Protein-truncating mutations are associated with an increased prevalence of spinal tumors.

The phakomatoses

The phakomatoses are a diverse set of disorders related principally by a similar tendency to produce patchy manifestations that affect the nervous system and various other tissues. All of the disorders involve the occurrence of benign neoplasms or hamartomatous growths, and all involve the action of a distinct gene that functions as a tumor suppressor. At present, none of the phakomatoses is amenable to effective medical treatment, so management is limited to surveillance and treatment of progressive lesions. The radiologist plays a key role in this management, participating in diagnosis and follow-up of affected patients.

Surgical excision of acoustic neuroma: patient outcome and provider caseload

OBJECTIVES/HYPOTHESIS

For many complex surgical procedures, larger hospital or surgeon caseload is associated with better patient outcome. We examined the volume-outcome relationship for surgical excision of acoustic neuromas.

STUDY DESIGN

Retrospective cohort study.

METHODS

The Nationwide Inpatient Sample (1996 to 2000) was used. Multivariate regression analyses were adjusted for age, sex, race, payer, geographic region, procedure timing, admission type and source, medical comorbidities, and neurofibromatosis status.

RESULTS

At 265 hospitals, 2643 operations were performed by 352 identified primary surgeons. Outcome was measured on a four-level scale at hospital discharge: death (0.5%) and discharge to long-term care (1.2%), to short-term rehabilitation (4.4%), and directly to home (94%). Outcomes were significantly better after surgery at higher-volume hospitals (OR 0.47 for fivefold-larger caseload, P <.001) or by higher-volume surgeons (OR 0.46, P <.001). Of patients who had surgery at lowest-volume-quartile hospitals, 12.3% were not discharged directly home, compared with 4.1% at highest-volume-quartile hospitals. There was a trend toward lower mortality for higher-volume hospitals (P =.1) and surgeons (P =.06). Of patients who had surgery at lowest-caseload-quartile hospitals, 1.1% died, compared with 0.6% at highest-volume-quartile hospitals. Postoperative complications (including neurological complications, mechanical ventilation, facial palsy, and transfusion) were less likely with high-volume hospitals and surgeons. Length of stay was significantly shorter with high-volume hospitals (P =.01) and surgeons (P =.009). Hospital charges were lower for high-volume hospitals (by 6% [P =.006]) and surgeons (by 6% [P =.09]).

CONCLUSION

For acoustic neuroma excision, higher-volume hospitals and surgeons provided superior short-term outcomes with shorter lengths of stay and lower charges.

Predictors of the risk of mortality in neurofibromatosis 2

To evaluate clinical and molecular predictors of the risk of mortality in people with neurofibromatosis 2 (NF2), we analyzed the mortality experience of 368 patients from 261 families in the United Kingdom NF2 registry, using the Cox proportional-hazards model and the jackknife method. Age at diagnosis, intracranial meningiomas, and type of treatment center were informative predictors of the risk of mortality. In Cox models, the relative risk of mortality increased 1.13-fold per year decrease in age at diagnosis (95% confidence interval [CI] 1.08-1.18) and was 2.51-fold greater in people with meningiomas compared with those without meningiomas (95% CI 1.38-4.57). The relative risk of mortality in patients treated at specialty centers was 0.34 compared with those treated at nonspecialty centers (95% CI 0.12-0.98). In a separate model, the relative risk of mortality in people with constitutional NF2 missense mutations was very low compared with those with other types of mutations (nonsense or frameshift mutations, splice-site mutations, and large deletions), but the CI could not be well quantified because there was only one death among people with missense mutations. We conclude that age at diagnosis, the strongest single predictor of the risk of mortality, is a useful index for patient counseling and clinical management (as are intracranial meningiomas). To ensure optimal care, we recommend that people with NF2 be referred to specialty treatment centers.

Molecular genetic analysis of the NF2 gene in young patients with unilateral vestibular schwannomas

Neurofibromatosis type 2 (NF2) must be suspected in patients presenting with a unilateral vestibular schwannoma at a young age who are therefore at theoretical risk of developing bilateral disease. We identified 45 patients aged 30 years or less at the onset of symptoms of a unilateral vestibular schwannoma. Molecular genetic analysis of the NF2 gene was completed on peripheral blood samples in all 45 and on 28 tumour samples. No pathogenic NF2 mutations were identified in any of the blood samples. NF2 point mutations were identified in 21/28 (75%) tumour samples and loss of heterozygosity (LOH) in 21/28 (75%) tumour samples. Both mutational hits were identified in 18/28 (65%) tumour samples. In one multilobular tumour, one (presumably first hit) mutation was confirmed which was common to different foci of the tumour, while the second mutational event differed between foci. The molecular findings in this patient were consistent with somatic mosaicism for NF2 and the clinical diagnosis was confirmed with the presence of two meningiomas on a follow up MRI scan. A further patient developed a contralateral vestibular schwannoma on a follow up MRI scan in whom neither of the truncating mutations in the vestibular schwannoma were present in blood. It is important when counselling patients with unilateral vestibular schwannomas to identify (1) those at risk of bilateral disease, (2) those at risk of developing other tumours, and (3) other family members at risk of developing NF2. Comparing tumour and blood DNA cannot exclude mosaicism in the index case and cannot, therefore, be used to predict those at risk of developing further tumours. However, identification of both mutations or one mutation plus LOH in the tumour and exclusion of those mutations in the blood samples of the sibs or offspring of the affected case may be sufficient to render further screening unnecessary in these relatives.

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.

Neurofibromatosis type 2

Neurofibromatosis type 2 is an often devastating autosomal dominant disorder which, until relatively recently, was confused with its more common namesake neurofibromatosis type 1. Subjects who inherit a mutated allele of the NF2 gene inevitably develop schwannomas, affecting particularly the superior vestibular branch of the 8th cranial nerve, usually bilaterally. Meningiomas and other benign central nervous system tumours such as ependymomas are other common features. Much of the morbidity from these tumours results from their treatment. It is now possible to identify the NF2 mutation in most families, although about 20% of apparently sporadic cases are actually mosaic for their mutation. As a classical tumour suppressor, inactivation of the NF2 gene product, merlin/schwannomin, leads to the development of both NF2 associated and sporadic tumours. Merlin/schwannomin associates with proteins at the cell cytoskeleton near the plasma membrane and it inhibits cell proliferation, adhesion, and migration.

Paediatric presentation of type 2 neurofibromatosis

BACKGROUND

Neurofibromatosis type 2 (NF2) is a highly penetrant autosomal dominant condition predisposing affected individuals to schwannomas and meningiomas. The proportion of children presenting with meningioma or schwannoma who have NF2 is not well described, and neither is the mode of presentation in most children with the inherited disease.

AIMS

To determine the frequency of childhood meningioma and schwannoma cases caused by NF2 and the mode of presentation.

METHODS

The records of the Manchester Children's Tumour Registry from 1954 were searched for cases of meningioma and schwannoma. Paediatric presentation in a large UK series of NF2 was also studied.

RESULTS

18% (61/334) of patients with NF2 on the UK database presented in the paediatric age group (0-15 years), frequently with the symptoms of an isolated tumour. More than half had no family history to alert the clinician to their susceptibility. Three of 22 children presenting with a meningioma on the Manchester Children's Tumour Registry have gone on to develop classic features of NF2.

CONCLUSIONS

Clinicians should suspect NF2 in children presenting with meningioma, schwannoma, and skin features, such as neurofibromas/schwannomas, but fewer than 6 café au lait patches, who thus fall short of a diagnosis of neurofibromatosis type 1.

Probability of bilateral disease in people presenting with a unilateral vestibular schwannoma

BACKGROUND

Some 4%-5% of those who develop vestibular schwannomas have neurofibromatosis type 2 (NF2). Although about 10% of these patients present initially with a unilateral vestibular schwannoma, the risk for a patient with a truly sporadic vestibular schwannoma developing contralateral disease is unknown.

METHODS

A United Kingdom survey of 296 patients with NF2 was reviewed for laterality of vestibular schwannoma at presentation and the presence of other NF2 related features. The time to presentation of bilateral disease was calculated for patients presenting with a unilateral tumour. Mutation analysis of the NF2 gene was carried out on all available cases presenting initially with unilateral disease.

RESULTS

Of 240 patients with NF2 with vestibular schwannomas, 45 (18%; 32 sporadic, 13 familial) had either a unilateral tumour or delay in detection between the first and contralateral tumours. Among those tested for NF2 mutations, eight of 27 and nine of 13 were identified among sporadic and familial cases respectively. Sporadic cases showed a high female to male ratio and 19 of 32 have not as yet developed a contralateral tumour (mean 4.1 years after diagnosis of the first). Thirteen of 32 sporadic patients developed a contralateral tumour (mean 6.5 years after the first tumour diagnosis, range 0-22 years) compared with 11 of 13 familial patients (mean delay 5 years, range 0-16 years). Seven of the 45 patients had neither a family history of NF2 nor evidence of related tumours at initial presentation (six before the age of 35 years).

CONCLUSION

The risk of patients with sporadic unilateral vestibular schwannomata developing a contralateral tumour in the absence of family history or other features of NF2 is low, but those presenting with other neurogenic tumours in addition to vestibular schwannoma are at high risk of harbouring an NF2 mutation in at least a proportion of their somatic cells.

Management of Neurofibromatosis Type 2

Neurofibromatosis type 2 (NF2), an as-yet incurable disease that predisposes patients to multiple intracranial and spinal tumors, requires a team approach to treatment, because of its multisystem nature. Included on the team should be neuro-otologists, neurosurgeons, ophthalmologists, geneticists, audiologists, speech therapists and other rehabilitative personnel, including counselors, psychologists and, occasionally, psychiatrists.

The challenge is to arrive at a treatment strategy that preserves useful hearing and quality of life without increasing the risk of complications to the facial nerve or compromising neurologic status. Choosing the best treatment approach involves considering a complex set of competing factors that affect various aspects of the patient's outcome.

Differential diagnosis of type 2 neurofibromatosis: molecular discrimination of NF2 and sporadic vestibular schwannomas

Patients who present with unilateral vestibular schwannomas either at a young age or with additional features of type 2 neurofibromatosis (NF2) are at risk of developing bilateral disease and transmitting a risk of neurogenic tumours to their offspring. We have identified 15 patients from a series of 537 with unilateral vestibular schwannomas who also had one or more of the following: other tumours (10/15), features of NF2 (3/15), or a family history of neurogenic tumours (5/15). No germline NF2 mutations were detected and in 7/9 cases where tumour material was available for analysis a germline mutation in the NF2 gene has been excluded. Although a possibility of gonosomal mosaicism still exists, exclusion tests for the offspring are now possible. We suggest a general strategy, based on analysis of tumour DNA, for distinguishing sporadic and familial cases of tumours caused by two hit mechanisms. Application of this strategy suggests that most instances of unilateral vestibular schwannoma which do not fulfil criteria for NF2 represent chance occurrences.

Genotype/phenotype correlations in type 2 neurofibromatosis (NF2): evidence for more severe disease associated with truncating mutations

Blood samples from 125 unrelated families with classical type 2 neurofibromatosis (NF2) with bilateral vestibular schwannomas have been analysed for mutations in the NF2 gene. A further 17 families fulfilling modified criteria for NF2 have also been analysed. Causative mutations have been identified in 54 (43%) classical families and six (35%) of those fulfilling modified criteria. Forty-two cases from 38 families with truncating mutations had an average age at onset of symptoms of 19 years and diagnosis at 22.4 years. Fifty-one cases from 16 families with splice site mutations (15 from six), missense mutations (18 from six), and large deletions (18 from five) had an average age of onset of 27.8 years and at diagnosis of 33.4 years. Subjects with truncating mutations were significantly more likely to have symptoms before 20 years of age (p<0.001) and to develop at least two symptomatic CNS tumours in addition to vestibular schwannoma before 30 years (p<0.001). There were also significantly fewer multigenerational families with truncating mutations. Four further truncating mutations were in mosaic form and were associated with milder disease than other similar mutations. This large study has confirmed the previous impression that truncating mutations are associated with severe disease, but caution has to be exercised in using mutation type to predict disease course.

Neurofibromatosis 1 and 2

Neurofibromatosis (NF) 1 and 2 are multisystem disorders associated with a variety of neoplastic and non-neoplastic manifestations that typically progress in severity during the lifetime of the affected patient. The importance of appropriately diagnosing these disorders stems from the fact that the natural history of an associated neoplasm, such as a peripheral nerve tumor or an optic glioma, may be significantly different depending on whether or not the lesion arises in a person with NF. In addition, the indications for therapeutic intervention, hierarchy of treatment options and long-term management goals may differ substantially for patients with NF-related versus sporadic tumors. Finally, recognition of the diagnosis comprises an essential step for providing appropriate multidisciplinary evaluation and counseling to affected patients and their families. This article addresses the principal manifestations of these disorders and provides a contemporary review of the diagnostic and therapeutic issues that arise in children with NF1 and NF2.

An extensive vestibular schwannoma with both intracranial spread and lateral extension to the external auditory canal

An extensive schwannoma in a 54-year-old woman is described. There was extension intracranially to involve the brain stem, laterally to fill the middle ear and external meatus, and inferiorly into the infratemporal fossa. Initially the intracranial portion of the tumour was excised. Later a second operation was undertaken to remove the residual tumour from the temporal bone and infratemporal fossa.