What are the other Names for this Condition? (Also known as/Synonyms)

• Acoustic Neurofibromatosis (due to Neurofibromatosis Type 2)
• Bilateral Acoustic Neurofibromatosis (due to Neurofibromatosis Type 2)
• NF2 (Neurofibromatosis Type 2)

What is Neurofibromatosis Type 2? (Definition/Background Information)

• Neurofibromatosis is a multisystem genetic disorder affecting the nervous system, skin, and skeletal muscles
• Neurofibromatosis Type 2 (NF2) is a genetic disorder characterized by bilateral non-cancerous tumors in the vestibular nerve. The vestibular nerve is responsible for hearing
• Neurofibromatosis Type 2 is caused by autosomal dominant mutation in the neurofibromin (NF) gene on chromosome 22. The NF 2 gene encodes a protein called merlin. Merlin protein acts as a tumor suppressor, and the absence of it leads to the development of various nervous system tumors
• Hearing loss is the most common manifestation. It may start as unilateral hearing loss (affecting one ear) and progress to bilateral hearing loss (affecting both the ears) over a period of time
• Many vestibular nerve tumors are closely followed and if causing significant signs and symptoms, they may be surgically removed. Currently, there are no effective ways  to prevent Neurofibromatosis Type 2
• The prognosis is variable from one individual to another. Individuals with signs and symptoms at an early age or with a high number of tumors have a poor prognosis

Who gets Neurofibromatosis Type 2? (Age and Sex Distribution)

• Neurofibromatosis Type 2 is a congenital condition that is present at birth. Even though the mutation in the NF2 gene is present during conception, the clinical manifestations usually appear in the late teens and 20s
• Both men and women are affected by this condition

What are the Risk Factors for Neurofibromatosis Type 2? (Predisposing Factors)

• A family history of neurofibromatosis is the main risk factor associated with Neurofibromatosis Type 2
• About half of the affected individuals diagnosed with NF2 do not have a family history of the condition. These individuals acquire the genetic mutations in a sporadic fashion (random event)

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Neurofibromatosis Type 2? (Etiology)

• In Neurofibromatosis Type 2, there is autosomal dominant mutation in the NF 2 gene on the chromosome 22 leading to defect in a tumor suppressor protein called merlin
• It has been observed that 50% of the affected individuals get this mutation by hereditary transmission and the other 50% develop the condition by spontaneous mutation
• Individuals, who have acquired a random mutation, can transmit the condition to subsequent generations

What are the Signs and Symptoms of Neurofibromatosis Type 2?

Signs and symptoms associated with Neurofibromatosis Type 2 include:

• The most common sign is hearing loss, which affects one ear (unilateral hearing loss) initially and then progress to affect both ears (bilateral hearing loss)
• It may be associated with impaired balance and ringing in the ear
• Presence of other brain tumors such as meningiomas and ependymomas
• Sub-cutaneous neurofibromas can develop similar to Neurofibromatosis Type 1
• Clouding of the lens due cataracts which occur at a young age

How is Neurofibromatosis Type 2 Diagnosed?

The diagnosis of Neurofibromatosis Type 2 may involve:

• Complete evaluation of medical history and a thorough physical exam
• MRI of the brain to localize the tumor of the vestibular nerve (and other tumors)
• Genetic testing to identify the mutation on chromosome 22 is helpful in diagnosing the disorder in those with a negative family history
• Audiometric evaluation to assess hearing. The size of the tumor is not related to the severity of the hearing loss
• Eye (ophthalmologic) evaluation to look for the development of cataract

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Neurofibromatosis Type 2?

Complications associated with Neurofibromatosis Type 2 include:

• Unilateral or, frequently, bilateral vestibular schwannomas leading to tinnitus (ringing in the ear), hearing loss, and/or problems with balance
• Vision impairment or vision loss due to cataract
• Development of other brain tumors such as meningiomas and ependymomas
• Seizures
• Hydrocephalus - fluid buildup in the brain
• Numbness or weakness in the arms or legs

How is Neurofibromatosis Type 2 Treated?

Treatment measures for Neurofibromatosis Type 2 include:

• Annual surveillance with MRI brain, eye, and auditory examination to monitor progression of the disorder and development of complications
• Surgical resection of the vestibular tumors. Hearing can be preserved in some cases after surgery
• For unresectable tumors, chemotherapy with Erlotinib, Bevacizumab has shown some improvement in hearing
• Auditory brainstem implants: This procedure does not provide high level of speech recognition, but helps to perceive environmental sounds that may help in communication

How can Neurofibromatosis Type 2 be Prevented?

• Currently, there are no specific methods or guidelines to prevent Neurofibromatosis Type 2, since it is a genetic condition
• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

What is the Prognosis of Neurofibromatosis Type 2? (Outcomes/Resolutions)

• Most of the morbidity in Neurofibromatosis Type 2 is caused by the vestibular nerve tumor (schwannoma) and invariably it is bilateral causing bilateral deafness
• The prognosis is variable from one individual to another
• Individuals with signs and symptoms at an early age have a worse prognosis. Also, individuals with a higher number of tumors have a poorer prognosis than those with lesser number of tumors

Additional and Relevant Useful Information for Neurofibromatosis Type 2:

Neurofibromatosis type 1 (NF1) manifests as benign tumors developing from the layer covering the cutaneous (skin) and optic (eye) nerves .This results in disfiguring outgrowths from the skin.