Neurofibromatosis Type II
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Clinically Relevant Anatomy
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Mechanism of Injury / Pathological Process
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NF2 is an autosomal dominant genetic disorder caused by mutations on chromosome 22[1]. Patients usually have multiple Central Nervous System tumors, but the presence of bilateral vestibular schwannomas is generally considered to be the hallmark of the disease.
NF2 is caused by mutations of the "Merlin" gene[2] which influences the form and movement of cells. The principal treatments consist of neurosurgical removal of the tumors and surgical treatment of the eye lesions.
Histological findings in NF2 tumors have shown several important and distinct characteristics in this population as opposed to non-
NF2 Acoustic Neuromas. Depending on the severity of the underlying mutation, multiple other CNS tumors can also be found, notably meningiomas, schwannomas, and gliomas, some of them involving cranial nerves.
Clinical Presentation
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Presenting symptoms[edit | edit source]
These may include the following:
- Hearing loss, ringing in the ears, and balance problems associated with vestibular nerve lesions
- Visual deficits
- Cranial nerve palsies
NF2 is associated with significant morbidity and decreased life span. Furthermore, diagnosis in childhood is often difficult because of the absence of central nervous system (CNS) involvement at a young age[3].
Complications of NF2[edit | edit source]
The following complications frequently occur:
Unilateral or, frequently, bilateral vestibular schwannomas leading to tinnitus, hearing loss, and/or problems with balance
Meningiomas, gliomas, ependymomas, and other cerebral, cerebellar, or spinal cord lesions that may result in neurologic deficits, seizures, and/or hydrocephalus
Peripheral nerve schwannomas, mixed tumors, and, occasionally, neurofibromas
Peripheral neuropathies
Visually significant juvenile cataracts
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Diagnostic Procedures[edit | edit source]
Clinical diagnosis of NF2 requires that an individual present with at least 1 of the 3 following disease indications:
- Bilateral eighth nerve masses visualized on MRI scan, using thin cuts, with and without gadolinium and on axial and coronal views
- First-degree relative with documented NF2 for an individual with a unilateral eighth nerve mass, imaged as already described
- First-degree relative with documented NF2 for an individual with at least 2 of the following findings: meningioma, glioma, schwannoma, juvenile cataract
However, because approximately half of cases result from new mutations, family history is often negative.
Diagnosis of NF2 involves the following:
Genetic testing
Imaging studies
Auditory, ophthalmic, and histologic examinations
Outcome Measures[edit | edit source]
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Management / Interventions
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Medical care for patients with NF2 consists of routine examinations focusing on early detection of some of the potential complications related to CNS or spinal cord lesions[4].
Guidelines for the care of the patient with NF2:
Annual neurologic examination looking for subtle deficits or changes in neurologic status that might suggest disease progression
Annual hearing screening with BAER, with referral to an audiologist for amplification, augmentation, or speech therapy recommendations
Annual MRI to monitor existing lesions or look for presymptomatic lesions
Annual ophthalmologic evaluations to monitor visual acuity
Treatment of symptomatic tumors is as follows:
Surgical resection represents the most common approach to clinically significant lesions
Rarely, radiation and/or chemotherapy may be recommended
Differential Diagnosis
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Neurofibromatosis Type 1 (NF1) differs from NF2 in that NF1 patients have large numbers of skin lesions, whereas NF2 patients generally have fewer skin lesions.
Key Evidence[edit | edit source]
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Resources
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References[edit | edit source]
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- ↑ Evans DG, Huson SM, Donnai D, Neary W, Blair V, Teare D, et al. A genetic study of type 2 neurofibromatosis in the United Kingdom. I. Prevalence, mutation rate, fitness, and confirmation of maternal transmission effect on severity. J Med Genet 1992;29:841-6
- ↑ Striedinger K, VandenBerg SR, Baia GS, McDermott MW, Gutmann DH, Lal A (November 2008). "The neurofibromatosis 2 tumor suppressor gene product, merlin, regulates human meningioma cell growth by signaling through YAP". Neoplasia 10 (11): 1204–12
- ↑ Matsuo M, Ohno K, Ohtsuka F. Characterization of early onset neurofibromatosis type 2. Brain Dev. Feb 13 2013
- ↑ Aboukais R, Baroncini M, Zairi F, Bonne NX, Schapira S, Vincent C, et al. Prognostic value and management of spinal tumors in neurofibromatosis type 2 patients. Acta Neurochir (Wien). May 2013;155(5):771-7.
