Central type neurofibromatosis

Central Type Neurofibromatosis

Central Type Neurofibromatosis, also known as Neurofibromatosis Type II (NF2), is a genetic disorder characterized by the development of noncancerous tumors in the nervous system, particularly affecting the brain and spinal cord. This condition is distinct from Neurofibromatosis Type I (NF1) and is less common. NF2 is primarily associated with bilateral vestibular schwannomas, which are tumors that develop on the vestibulocochlear nerve, leading to hearing loss and balance issues.

Genetics

Central Type Neurofibromatosis is caused by mutations in the NF2 gene, which is located on chromosome 22. The NF2 gene encodes a protein called merlin or schwannomin, which acts as a tumor suppressor. Mutations in this gene lead to the loss of function of merlin, resulting in uncontrolled cell growth and tumor formation. NF2 is inherited in an autosomal dominant pattern, meaning that a single copy of the mutated gene is sufficient to cause the disorder.

Clinical Features

The hallmark of NF2 is the development of bilateral vestibular schwannomas, which typically present with:

• Hearing Loss: Progressive hearing loss is often the first symptom, due to the impact on the auditory nerve.
• Tinnitus: Ringing in the ears is a common symptom associated with vestibular schwannomas.
• Balance Problems: As the tumors affect the vestibular nerve, patients may experience issues with balance and coordination.

Other tumors associated with NF2 include:

• Meningiomas: Tumors that arise from the meninges, the protective layers surrounding the brain and spinal cord.
• Ependymomas: Tumors that develop from the ependymal cells lining the ventricles of the brain and the central canal of the spinal cord.
• Schwannomas: Tumors that can occur on other cranial and peripheral nerves.

Diagnosis

Diagnosis of NF2 is based on clinical criteria, genetic testing, and imaging studies. MRI is the preferred imaging modality to identify vestibular schwannomas and other associated tumors. Genetic testing can confirm the presence of mutations in the NF2 gene.

Management

Management of NF2 involves a multidisciplinary approach, including:

• Regular Monitoring: Routine MRI scans to monitor tumor growth.
• Hearing Aids and Cochlear Implants: To manage hearing loss.
• Surgical Intervention: To remove tumors that are causing significant symptoms or are life-threatening.
• Radiation Therapy: Stereotactic radiosurgery may be used for certain tumors.

Prognosis

The prognosis for individuals with NF2 varies depending on the size and location of the tumors and the effectiveness of treatment. Early diagnosis and intervention can improve quality of life and outcomes.

Also see

• Neurofibromatosis Type I
• Schwannoma
• Meningioma
• Ependymoma