Neurofibromatosis (NF) is a condition that causes tumors to grow
on nerve tissue, producing skin and bone abnormalities.
NF is often diagnosed in childhood, occasionally in infancy (in
children with severe cases), but usually around 3-16 years of age.
Effects of the disease vary widely - some children live almost
unaffected by the condition; rarely, others might be severely
disabled.
There's no specific cure for NF, but tumors usually can be
removed and related complications treated. Because learning
disabilities occur in about half the children with NF, some might
need extra help in the classroom.
About Neurofibromatosis
Neurofibromatosis is a
neurocutaneous syndrome
passed down through the parents' genes, and it affects the
brain, spinal cord, nerves, skin, and other systems in the
body.
Neurofibromatosis is defined by tumors, called neurofibromas,
that grow along nerves in the body, or on or under the skin. As the
tumors increase in size, they can press on vital areas of the body,
causing problems in the way the body functions.
Neurofibromas often first appear in childhood, especially during
puberty. The first noticeable sign is almost always the presence of
brown café au lait spots. These distinctive spots don't hurt or
itch and never progress to anything more serious than spots. They
can be found anywhere on the body, though not usually on the face.
Tiny ones - freckles - may be seen under the arms or in the groin
area.
Many neurofibromas can be removed. Although usually benign
(noncancerous), an estimated 3%-5% become cancerous.
Of the two types of neurofibromatosis - NF1 and NF2 - NF1 is
more common, occurring in 1 of every 4,000 births and affecting an
estimated 100,000 Americans. It is also known as von Recklinghausen
disease.
NF2 is characterized by the presence of bilateral acoustic
neurofibroma-like tumors and is rarer, seen in 1 in 50,000 births.
People with NF2 usually develop benign tumors on the nerves in
their ears, causing hearing loss, eventual deafness, and problems
with balance.
The severity of both types of neurofibromatosis varies greatly.
In families where more than one person has NF, it can present with
different physical signs and complications for each person. At
diagnosis, it isn't possible to know right away whether a case
will be mild or lead to severe complications.
Causes of NF
Both types of neurofibromatosis are autosomal dominant genetic
disorders, which means an affected person has 1 chance in 2 of
passing it on with each pregnancy. Neurofibromatosis also can be
the result of a spontaneous change (mutation) in the genetic
material of the sperm or egg at conception in families with no
previous history of NF. About half of cases are inherited, and the
other half are due to spontaneous genetic mutation.
NF 1 and NF 2 are each related to changes in separate genes. The
NF1 gene is located on chromosome 17, and NF2 has been traced to
chromosome 22. These findings are important because they may
eventually lead to the development of a blood test or other
genetic test
to find out if a relative has NF.
Signs and Symptoms
NF1 is sometimes diagnosed in younger children, especially those
with more severe forms of the disorder. One key to early diagnosis
of mild NF is the appearance of café-au-lait spots on the skin.
Many people who do not have NF have a few café-au-lait spots.
But if a young child has five or more, at least 1/2 inch in size
(roughly the size of a dime), a doctor will look for other clues
that may indicate NF, including neurofibromas - tumors on, under,
or hanging off the skin - and Lisch nodules, tiny, noncancerous
tumors on the iris (the colored part of the eye). Lisch nodules are
of no clinical significance except that they help confirm a
diagnosis of NF.
Neurofibromas often become evident on various parts of the body,
beginning at the arms, around 10 years of age. A child may also
develop freckling in the folds of the skin of the armpit or groin
or on other parts of the body where the skin creases.
Abnormalities of the skeleton, such as the thinning or
overgrowth of the bones in the arms or lower leg, curvature of the
spine (
scoliosis
), and other bone deformities also may be features of NF1.
NF2 is usually not diagnosed until a child is older. Hearing
loss in the late teens and early twenties is often among the first
symptoms of the disorder, and is caused by tumors growing on the
auditory nerves (which carry electrical impulses from the inner ear
to the brain, allowing us to hear) on one or both sides.
Other symptoms of NF2 include continuous ringing in the ears,
headache, facial pain or weakness, and feeling unsteady or off
balance.
Diagnosis and Treatment
Neurofibromatosis is usually diagnosed based on a combination of
findings. A child must have at least two of the following signs to
be diagnosed with NF1:
- café-au-lait spots of a certain number, size, and
location
- the appearance of two or more neurofibromas (often resembling
pea-sized bumps on the skin)
- Lisch nodules on the irises
- an optic glioma (tumor along the main nerve of the eye that
is responsible for sight)
- certain skeletal abnormalities
- a family member with NF1
- freckling under the arms or in the groin
Tests like magnetic resonance imaging (MRI) and X-rays may be
used to screen for tumors or evidence of skeletal problems. A
child's
head circumference
will be measured, as kids with symptoms of NF can have a
circumference that's larger than normal for their age. Blood
pressure will be monitored. Doctors also take a detailed personal
history, looking for signs of learning difficulties.
To diagnose NF2, doctors will check for any evidence of hearing
loss. They'll order audiometry (hearing tests) as well as
imaging tests to look for tumors in the nerves of the ears, spinal
cord, or brain. They'll also determine if there's a family
history of NF2.
Genetic testing is now available for people with a family
history of either NF1 or NF2, though such testing is still not 100%
sensitive. Amniocentesis or chorionic villus sampling can sometimes
determine if an unborn child has the condition.
Treatment for NF1 includes removal of the neurofibromas for
cosmetic purposes, treating the complications (see below), and
getting intervention for children with learning disabilities. Kids
will be referred to appropriate medical specialists to monitor and
treat complications, which may include:
- seizures (up to 40% of children with NF1 have them)
- high blood pressure
- scoliosis
- speech impairment
- optic nerve tumors (which can cause vision problems leading
to blindness)
- early or delayed onset of puberty
Rarely, neurofibromas can become cancerous (3%-5% of cases). In
these occurrences,
surgery
,
chemotherapy
, or
radiation
may be necessary.
With NF2, surgeons will likely need to remove the auditory nerve
tumors, which may cause deafness afterward. When parts of the
auditory nerve are removed, hearing aids won't work.
In 2000, the U.S. Food and Drug Administration (FDA) approved an
auditory brainstem implant for people with NF2 who have lost their
hearing. This device transmits sound signals directly to the brain,
enabling the person to hear certain sounds and speech.
Currently, researchers are conducting trials with medications in
the hopes they'll be able to offer more treatment options.
Caring for Your Child
The first noticeable sign of neurofibromatosis usually is the
presence of multiple café-au-lait spots. If your child has several
of these spots, ask your doctor to do a thorough examination; he or
she may need to screen your child for other signs of NF.
If your child has already been diagnosed with NF and you notice
that a growing tumor is beginning to cause a problem, tell your
doctor immediately.
One of the most important things you can do is get early
intervention if your child has learning disabilities. It also helps
to seek out support groups that can provide your family with
practical advice and encouragement.
Remember, most people (about 60%) diagnosed with NF1 have only
relatively mild signs of the disorder, like café-au-lait spots and
a few neurofibromas on the surface of the skin, which require
little or no treatment.
Kids diagnosed with mild NF who remain fairly healthy into early
adulthood are less likely to develop more serious complications
later in life. Kids diagnosed with more serious forms often have
correctable complications and with appropriate help and support can
lead happy and productive lives.
Reviewed by:
Louis E. Bartoshesky, MD, MPH
Date reviewed: October 2008
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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