Introduction
Neurofibromatosis is a group of genetic disorders with neurological manifestations that causes benign or noncancerous tumors. The tumors occur on the nerves and other parts of the body. In many people, neurological problems are barely noticeable. There are three types of neurofibromatosis which include neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis. NF1 disorder causes skin pigmentation and tumors in the nerves and deep layers of the skin. Schwannomatosis is a rare disorder that consists of multiple schwannomas (a nerve sheath tumor that consists of Schwann cells).
What Is Neurofibromatosis Type 2?
Neurofibromatosis type 2 (NF2) is a genetic disorder that leads to noncancerous tumors in the central nervous system (CNS). The tumors rapidly grow on the nerves of the spine and the brain. The growths develop along the nerves that transfer the information from the inner ear to the brain. Such tumors are called vestibular schwannomas or acoustic neuromas. Often the tumors grow on both the left and right sides of the auditory nerve and are known as bilateral vestibular schwannomas.
One in 33,000 people worldwide is affected by this condition, and both males and females are affected equally. 18 to 24 years of age is this condition's most common age group.
There are two forms of NF2:
Wishart-Phenotype - This type is characterized by multiple spinal and cerebral lesions that occur in people under 20 years of age.
Feiling-Gardner Phenotype - This type is associated with a single central tumor that occurs in people above 20 years of age.
What Causes Neurofibromatosis Type 2?
Mutation in the NF2 gene leads to this disorder.
NF2 Gene: The NF2 gene provides instruction for the production of a particular protein known as merlin or schwannomin. The merlin is made in the nervous system, mostly in specialized Schwann cells. These merlin cells help signal the cell growth, shape, and attachment of cells to each other. If a tumor tries to occur in the nervous system, these cells suppress them.
More than 400 mutations in the NF2 gene are seen in people with neurofibromatosis type 2. This gene mutation causes an abnormally short version of the merlin protein. The normal tumor-suppressing function is not possible in the cells, and the Schwann cell multiplies rapidly in the central nervous system.
Who Is Susceptible to Neurofibromatosis Type 2 (NF2)?
According to various estimates, one in 25,000 to one in 40,000 people worldwide are born with NF2. Equal numbers of men and women are affected. Every ethnic group is impacted. Although NF2 can be inherited, about 50 % of those who have it have no known relatives. Family history is the greatest risk factor because it can be inherited.
Children with NF2 frequently exhibit signs of brain and spinal cord malignancies. Adults diagnosed with NF2 are typically between the ages of 18 and 24. Due to tumors on the auditory nerves, they frequently experience issues.
What Are the Symptoms Of Neurofibromatosis Type 2?
Early signs and symptoms of NF2 include:
-
Difficulty in balancing.
-
Headache.
-
Ringing in the ear (tinnitus).
-
Hearing loss.
-
Vision impairment.
-
Numbness in arms and legs.
-
Fluid deposition in the brain.
How Is Neurofibromatosis Type 2 Diagnosed?
The diagnosis is done in early adulthood (20 to 30 years). The doctor may examine the patient clinically and note the patient’s medical and family history. To confirm that the symptoms are related to NF2, some tests are advised, which include:
Hearing Test: An audiometry test is done to examine the ability to hear sounds. Some simple tests are done to check the patient’s hearing ability. A tuning fork is tapped in the air at each side of the ear to check the level of air conduction. Additionally, some of the formal hearing tests can be performed to check the measure of hearing, such as speech audiometry (detect and repeat spoken words through a headset) and tympanometry (vibration measured of the eardrum and middle ear pressure).
Magnetic Resonance Imaging (MRI): An MRI scan of the brain is done to determine the size and location of the tumor. A healthcare professional will ask the patient to lie down on the bed of the machine. Once the patient is settled, the expert will operate the machine in a different chamber. The machine will take several scans, which take around half an hour to complete. The sound of the machine will be very loud and high-pitched. The expert will be able to communicate with the patient with an intercom connected to the chambers. A headphone can be placed to listen to music to calm the patient.
Genetic Testing - A genetic test is done to confirm the diagnosis by examining the DNA and changes in the genes that cause NF2. Depending on the condition, genetic testing can be done by various methods. One of the most common methods includes a blood test. A healthcare professional will take the blood sample from the arm’s vein. The sample is collected in a vial or test tube and sent to a laboratory for further testing.
How Is Neurofibromas Type 2 Managed?
Treatment options include:
Surgery - Different surgical methods are done to remove an acoustic neuroma. Depending upon the size and location, the tumors can be surgically removed. One additional method is radiosurgery, in which therapeutic radioactive waves are focused on the tumors and destroyed without harming any surrounding tissues or leaving any scars.
Medication - Bevacizumab has resulted in reducing the growth of tumors and hearing improvement.
Monitoring - Not many treatment options are available for NF2, so proper monitoring of the symptoms and regular visits to the doctor are recommended.
Additional Treatment Options - Cochlear implants (an electronic device to stimulate the cochlear nerve) and auditory brainstem implants or ABIs (an implant used when a cochleovestibular nerve is damaged and does not function properly) are given to regain hearing abilities.
Conclusion
Neurofibromatosis is a group of inherited disorders and is divided into three types one such type is neurofibromatosis type 2. NF2 is a genetic disorder that leads to tumors in the nerves of the central nervous system (CNS). It is caused due to genetic mutation, and symptoms are visible from early adulthood. It can be easily diagnosed by various methods such as magnetic resonance imaging (MRI), genetic, and hearing tests. Though there is no permanent cure to date, many different modalities, such as surgery and hearing implants, can help an individual live a healthy and confident life.
