Neurofibromatosis: Types, causes, and symptoms

Neurofibromatosis is an incurable genetic disorder of the nervous system. It mainly affects the development of nerve cell tissues. Tumors known as neurofibromas develop on the nerves, and these can lead to other problems.

The tumors may be harmless, or they may compress the nerves and other tissues, leading to serious damage.

Neurofibromatosis (Nf) is the most common genetic neurological disorder that is caused by a single gene. The mutation in the gene means that the nerve tissue is not properly controlled.

There are three types: Nf1, Nf2, and schwannomatosis. They are not related. This article will focus mainly on Nf1 and Nf2.

Treatment

[cochlear implant]
A cochlear implant can help people with hearing loss.

Although there is no cure for neurofibromatosis, its symptoms can be treated.

Neurofibromas are not generally painful, but if their location on the body means that they graze or catch on clothing, they can be removed. This reduces the risk of itching, infection, numbness, and general discomfort. However, they may grow back.

Hypertension can be treated with medications and lifestyle changes. Regular checks are advised.

If tumors growing on the optic nerve are affecting eyesight, they can be surgically removed.

Scoliosis, or curvature of the spine, can be corrected through surgery or by wearing a back brace.

Normally, the tumors are regularly monitored, and treatment is given as required.

Acoustic neuroma

Surgery for acoustic neuromas does not always improve hearing and may worsen it. The decision to remove an acoustic neuroma will depend on the size of the tumor and how rapidly it is growing, not only on hearing loss.

Sometimes a surgeon will insert an auditory brain stem implant (ABI) to help a person’s hearing. They may remove a vestibulocochlear nerve tumor at the same time.

The surgeon will make an incision in the skin of the side of the head and remove some of the bone behind the ear. This exposes the tumor for removal and gives access to the brain stem below.

People with an ABI wear an external receiver and speech processor. This converts sound into electrical signals, which are then sent to the implant.

A cochlear implant may be fitted after removing the tumor. This small, complex electronic device can help to provide a sense of sound for someone with profound or severe hearing problems.

An external portion is placed behind the ear, and a second portion is surgically placed under the skin. The implant consists of a microphone, a speech processor, and a transmitter and receiver or stimulator, to receive signals from the speech processor and convert them into electric impulses.

A group of electrodes collects the stimulator impulses and sends them to different parts of the auditory nerve.

The implant cannot restore normal hearing, but it can provide a useful representation of sounds, and this can help a person to understand speech.

An audiologist can advise on managing balance and tinnitus, or ringing in the ears. Some people with neurofibromatosis learn to lip read and use sign language.

Radiotherapy or chemotherapy may help to shrink a tumor, and work is under way to find a drug that could prevent or reduce the tumors.

Symptoms

The symptoms of neurofibromatosis depend on the type.

The disorder can spread throughout the whole body, leading to tumors and unusual skin pigmentation.

It can manifest as bumps under the skin, colored spots, bone problems, pressure on spinal nerve roots, and other neurological problems.

Learning disabilities, behavioral problems, and vision or hearing loss may arise.

Nf1

Some individuals with Nf1 have only a skin condition and no other related medical problems. Signs and symptoms generally appear during early childhood. They are not usually harmful to health.

[skin growths]
Skin growths may occur with both Nf1 and Nf2.

Birthmarks and freckles are common. Coffee-colored marks appear on the skin, usually at birth. If more than six marks appear by the age of 5 years, this may indicate Nf1. The number of spots can increase, and they may grow larger and darker with time.

Freckles may appear in an unusual location, such as the groin, under the breasts, or in the armpits.

Neurofibromas are tumors, generally non-cancerous, that grow on the nerves of the skin, and sometimes on nerves deeper inside the body. They look like lumps under the skin. In time, more may develop, and they may get bigger. Neurofibromas may be soft, or firm and round.

Lisch nodules can also occur. These are very small brown spots that may appear in the iris of the eye.

People with Nf1 also face a higher risk of hypertension, or high blood pressure.

Nf2

Nf2 is a more serious condition in which tumors grow on nerves deep inside the body.

An acoustic neuroma is a common type of brain tumor that develops on the nerve that goes from the brain to the inner ear.

Symptoms may include:

facial numbness, weakness and sometimes paralysis

gradual, or more rarely sudden, hearing loss

loss of balance, dizziness, and vertigo

tinnitus, or ringing in the affected ear

Symptoms may get worse as the tumor grows. The neuroma may compress the brainstem, which can be life-threatening. A small tumor may not cause any problems.

Sometimes, tumors develop on the skin, brain, and spinal cord, with potentially serious consequences. Some tumors develop rapidly, but most grow slowly, and the effect may not be noticeable for several years.

Regular monitoring can enable tumors to be removed before complications arise.

Spots of light brown pigmentation may occur, but they will be less common and fewer in number than in people with Nf1.

Cataracts may occur. If a child develops a cataract, this may be a sign of Nf2. These are easily removed, and not generally problematic if treated.

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Types

The three types of neurofibromatosis are Nf1, Nf2, and schwannomatosis.

Type 1 neurofibromatosis (Nf1)

Also known as von Recklinghausen’s disease, von Recklinghausen NF, or peripheral neurofibromatosis, NF1 is the most common type of neurofibromatosis. It mostly results from a mutation, rather than a deletion, of the Nf1 gene. It is thought to affect 1 in every 3,000 people.

Shortly after birth, birthmarks may appear in different parts of the body.

During late childhood, lesions, or tumors, may appear on or under the skin, numbering from a few to thousands. Occasionally, the tumors become cancerous.

Nf1 can be barely noticeable, it can be unsightly, or it can lead to potentially serious complications. Around 60 percent of cases are minor.

Did the ‘elephant man’ have Nf1?

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