Neurofibromatosis: Causes, Symptoms and Treatment

Neurofibromatosis causes tumor to grow on nerves and gives rise to many other abnormalities like skin changes and bone deformities. The tumor begins in the cells that make up the myelin sheath, which is a thin membrane that envelops and protects nerve fibers. The type of the tumor depends on its position in the body and the kind of cells involved. Neurofibromas is one of the most common tumor that develops in the tissue surrounding the peripheral nerves. The tumor is non-cancerous, but can become cancerous over time. This genetic disorder occurs in both sexes and in all races and ethnic groups.

Neurofibromatosis first appears in childhood, especially during puberty. The first observable sign is the presence of brown cafe-au-lait spots. These spots don't hurt or itch and can be found anywhere on the body, especially under the arms and groin areas. Scientists have categorized this disorder into two types: neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2).

Causes of Neurofibromatosis

Neurofibromatosis is an autosomal dominant genetic disorder, that is, an affected person has 50% chance of passing it on with each pregnancy. It can be the result of a mutation in the genetic material of the sperm or egg at conception in families having no previous history of neurofibromatosis. Nearly 50% of the cases are inherited and rest are due to spontaneous genetic mutation. NF1 and NF2 are linked to mutations in separate genes. The NF1 gene has been traced to chromosome 17 and the NF2 gene is located on chromosome 22. These findings are important, as it may help during a blood test or other genetic tests to know if a relative has NF.

Neurofibromatosis Type 1 (NF1)

NF1 is the most common type of the neurofibromatosis that occurs normally during adolescence. Earlier, NF1 was known as peripheral neurofibromatosis or von Recklinghausen's neurofibromatosis, as some of its symptoms like skin spots and tumors seemed to be restricted only to the outer nerves or peripheral nervous system of the affected person. But later the name was changed, as central nervous system tumors are known to occur in NF1. The benign tumor may originate on the skin (cutaneous), under the skin (subcutaneous) and in the connective nerve tissue (neurofibromas). It can be painful and in about 3-5% of cases, it becomes malignant.

Signs and Symptoms of NF1

• Curvature of the spine (scoliosis)
• More than five light brown skin spots about 5 millimeters in diameter in patients under the age of puberty or more than 15 millimeters in adults
• Freckling in the armpit and groin areas
• Benign growths on the iris of the eye known as lisch nodules or iris hamartomas
• Tumor on the optic nerve called as optic glioma
• Enlargement and deformity of the bones that may cause chronic pain
• Hearing loss and learning disabilities

Neurofibromatosis Type 2 (NF2)

NF2 is less common type of neurofibromatoses which is characterized by bilateral tumors on the eighth cranial nerve. The tumor mainly occurs on the vestibular nerve (another branch of the eighth cranial nerve near the auditory nerve). It causes damage to the neighboring nerves and vital structures such as cranial nerves and the brainstem which can be life-threatening. It is also known as bilateral acoustic neurofibromatosis or central neurofibromatosis and is diagnosed during late teens and early twenties.

Signs and Symptoms of NF2

• Hearing loss
• Ringing in the ears
• Headache
• Facial pain or weakness
• Feeling unsteady and off balance
• Cataract at an early age
• Glioma and meningioma

Diagnosis and Treatment for Neurofibromatosis

Diagnosis for neurofibromatosis involves several baseline studies like hearing and vision screening tests, psychologic testing to evaluate possible learning disorders, electroencephalogram (EEG), X-rays of the bones and head CT (computed tomography) or MRI (magnetic resonance imaging).

The treatment for NF1 includes removal of the neurofibromas for cosmetic purposes, getting intervention for children with learning disabilities and treating the complications like seizures, scoliosis, speech impairment, high blood pressure, optic nerve tumors and early or delayed onset of puberty. It's rare that neurofibromas become cancerous, but for such occurrences, surgery, chemotherapy or radiation treatment can be done. In 2000, the US Food and Drug Administration (FDA) approved an auditory brainstem implant which transmits sound signals directly to the brain for people with NF2 who have lost their hearing, and enables them to hear certain sounds and speech.

There is no specific treatment for NF, but genetic counseling and early detection of treatable conditions or complications can benefit people. The asymptomatic patient needs to be re-examined yearly and a symptomatic patient can be benefited from surgical treatment of tumors.