What is Neurofibromatosis 2?
This less common of the neurofibromatoses affects about 1 in 25,000 persons. NF2 is characterized by bilateral (occurring on both sides of the body) tumors on the eighth cranial nerve. It was formerly called bilateral acoustic neurofibromatosis or central neurofibromatosis because the tumors, which cause progressive hearing loss, were thought to grow primarily on the auditory nerve, a branch of the eighth cranial nerve responsible for hearing. Scientists now know that the tumors typically occur on the vestibular nerve, another branch of the eighth cranial nerve near the auditory nerve. The tumors, called vestibular schwannomas for their location and for the type of cells in them, cause pressure damage to neighbouring nerves. In some cases, the damage to nearby vital structures, such as other cranial nerves and the brainstem, can be life-threatening.
What are the signs and symptoms of NF2?
- Bilateral eighth nerve tumors,
- A parent, sibling, or child with NF2 and a unilateral eighth nerve tumor, or
- A parent, sibling, or child with NF2 and any two of the following;
- Or cataract at an early age
When do symptoms appear?
Affected individuals may notice hearing loss as early as the teen years. In addition to changes in hearing that may occur in one or both ears, other early symptoms may include tinnitus (ringing noise in the ear) and poor balance. Headache, facial pain, or facial numbness, caused by pressure from the tumors, may also occur.
How is NF2 treated?
Treatments for NF2 are aimed at controlling the symptoms. Improved diagnostic technologies, such as MRI (magnetic resonance imaging), can reveal tumors as small as a few millimeters in diameter, thus allowing early treatment. Surgery to remove tumors completely is one option, but may result in hearing loss. Other options include partial removal of tumors, radiation, and, if the tumors are not progressing rapidly, the conservative approach of watchful waiting.
Are there prenatal tests for the neurofibromatoses?
Genetic testing is available for families with documented cases of NF1 and NF2. Genetic analysis can be used to confirm clinical diagnosis if the disease is a result of familial inheritance. New (spontaneous) mutations cannot be confirmed genetically. Prenatal diagnosis of familial NF1 or NF2 is also possible utilizing amniocentesis or chorionic villus sampling procedures. Genetic counselors can provide information about these procedures and offer guidance in coping with the neurofibromatoses.