Neurofibromatosis 2 (previously called
bilateral acoustic neurofibromatosis or central neurofibromatosis
and abbreviated as NF2, NFII or BAN) affects about 1 in 40,000 people
without regard to sex or race. Patients with NF2 develop tumors
throughout the body and must cope with a variety of neurological
problems. The following sections outline what is currently known
about this disorder. We hope that if you or your family is dealing
with NF2, you will use this introduction to asked more informed
questions of your own healthcare providor.
Figure 1. Bilateral Vestibular Schwannomas. These MRI
scans show the typical appearance of bilateral vestibular schwannomas.
In part A, a 14 year old boy has tiny tumors (arrows) on his
eighth cranial nerves. The tumors lie within the bones of the
skull and do not touch the base of the brain. Tumors of this
size are often asymptomatic; sometimes a person will notice
only that they have difficulty using a telephone in one ear.
In part B, the 50 year old uncle of the teenager in part A has
huge tumors at the junction of the pons and the lobes of the
cerebellum. These tumors are pressing on the base of the brain,
and could only be removed with damage to the eighth cranial
nerve with resulting deafness. The goal of current NF2 management
is to detect tumors while they are the size seen in part A and
amenable to treatment.
Almost all individuals with NF2 develop
tumors on both nerves to the ears (also called the eighth cranial
nerve). The eight cranial nerve has two portions: the acoustic (hearing)
nerve which carries information about sound to the brain and the
vestibular nerve which carries balance information the brain. The
early symptoms of NF2 are usually symptoms of dysfunction of these
nerves: hearing loss, ringing in the ears (called tinnitus) and
problems with balance.
Although tumors on the eighth cranial
nerve are most common, most persons with NF2 develop tumors on other
nerves also. These tumors are called schwannomas because they arise
from the Schwann cells. Schwann cells support and protect nerve
cells and provide nerves with the insulation they need to conduct
information. The symptoms of a schwannoma will depend on its location.
Those that arise on cranial nerves (like the eight cranial nerve
tumors) affect the head and neck unless they grow large enough to
push on the base of the brain (called the brainstem) and affect
the body also. Those which grow on nerves as they exit the spinal
cord may cause numbness of a part of the body; some tumors may grow
large enough to press on the spinal cord and cause weakness and
numbness in the legs.
Figure 2. Spinal Schwannoma. A dumbbell shaped tumor is
outlined as it begins on a spinal root and extends both out
of and into the spinal canal (C).
Those that grow in the bundles of nerves
gathered in the armpits and groin area may cause weakness in one
arm or leg. Schwannomas may even grow in tiny nerves in the skin
where one can see them.
These peripheral schwannomas rarely
cause neurological symptoms, but they may rub on clothing or be
In addition to schwannomas, persons
with NF2 frequently develop other sorts of tumors which grow on
the coverings of the brain and spinal cord. The most frequent such
tumor is called a meningioma; more rarely ependymomas or astrocytomas
These tumors may cause many different
kinds of neurological symptoms depending on their location. As with
schwannomas, a physician may detect signs of a tumor on a detailed
neurological examination before a patient can detect symptoms in
every day life, making an annual neurological examination important
for every NF2 patient. Finally, some persons with NF2 develop a
special sort of cataract, known as a juvenile posterior sublenticular
opacity, or have other problems with the eyes. Since all individuals
with NF2 are at risk for losing hearing, it is very important to
have a detailed eye examination by a specialist familiar with NF2
to prevent loss of sight also.
|Deafness on one side--35%
Deafness on both sides--9%
Ringing in one or both ears--10%
Trouble with balance--8%
Weakness in one arm or leg--12%
Numbness or tingling in an arm or leg--6%
No symptom, but detected on screening because a parent was affected--11%
Table 1. The first symptoms
of NF2. These are the first symptoms of 120 patients with
NF2 studied by Dr. Gareth Evans in Great Britain. This study
did not include skin tumors or cataracts as a first symptom.
The time course of NF2 varies from
individual to individual. Most individuals with NF2 get their first
neurological symptoms during late teenage years or in their early
20s. Skin tumors and cataracts may be apparent on examination
even earlier in a child with NF2. A few people develop deafness
and neurological symptoms in childhood and some do not have problems
until their 40s or 50s. Unfortunately, studies have
shown that a person will often have symptoms for many years before
the true nature of the problem is realized. Since the tumors of
NF2 grow slowly, it is likely that they are present in an individual
form many years before they cause symptoms.
The diagnosis of NF2 depends on the
recognition of the signs and symptoms, coupled with a comprehensive
examination and imaging studies of the brain and spine. Children
of an affected individuals may often be diagnosed by a blood
test before any symptoms are apparent. Rarely, individuals
have some of the problems with NF2 without the development of bilateral
vestibular schwannoma. Researchers are still trying to determine
what causes these unusual cases and such persons may wish to contact
center to learn more about such studies. Adults with a single
schwannoma (including a single vestibular
schwannoma), meningioma or ependymoma who do not have an
affected relative do not have NF2.
Presently, the only treatments available
for the tumors of NF2 are surgery
and radiation therapy. Most persons with NF2 require at least
one operation during their lifetime. Since the tumors of NF2 lie
on nerves and/or near the brain and spinal cord, their surgical
removal is not without risk.
Figure 3. Skin tumors in a patient with NF2. Photo courtesy
of Dr. Dilys Parry of the National Institutes of Health. Although
people with NF1 often get large numbers of skin tumors, people
with NF2 usually have less then 10.
Surgery in these small and delicate areas may cause further injury
to nerves--and further neurological problems. For these reasons
the potential benefits and risks of every contemplated surgical
procedure should be carefully considered and discussed with a health
care providor familiar with the disease. When surgery is no longer
an option for a particular person because of their medical problems
or the size or location of a tumor, radiation therapy may be considered.
As with surgery, radiation therapy has both risks and benefits which
must be carefully considered. Recently, a device has been developed
by the House Ear Institute
in conjunction with the Cochlear
Corporation that allows some individuals deafened by NF2
to perceive sound. This device (known as an auditory brainstem implant
or ABI) is now undergoing investigational trials at a number of
centers world wide.
Once someone has been found to have
NF2, a number of tests may be helpful to define its nature and progression.
Magnetic resonance imaging (MRI) scans are used to visualize the
anatomy of the body. They are most commonly taken of the brain,
but may also be used to "see" the spine or nerves in the
arms and legs.
Figure 4. Multiple meningiomas (arrows) in a patient with NF2.
Older patients with NF2 may develop tumors throughout the
brain. These tumors are very slow growing, and their resection
should be carefully considered. If a tumor is not causing severe
symptoms, removing it may cause more damage then merely watching
To undergo an MRI scan a patient is
asked to lie very still on a small bed which slides into a donut-shaped
machine. Magnets are activated around the patient and produce a
banging sound. At some point, the patient may be injected with a
dye that enhances the appearance of some parts of the brain. No
X-irradiation is used. Repeated MRI scans over time will define
if a tumor is static or growing. This is important information since
a large static tumor may cause fewer problems than a small but growing
Although MRI scans can show very detailed
structural information (what your body looks like), they cannot
show functional information (how well your body is working). Audiometry
and brainstem auditory response (BAER) testing show how well the
hearing portion of the eighth cranial nerve is working. Information
from audiometry and BAER augment the structural information from
an MRI. Repeated testing will determine if the functional aspects
of a tumor are changing and help a patient and physician to determine
the best possible time for surgical intervention.
NF2 is a genetic disease that is passed
from parent to child at the time of conception. About one half of
persons with NF2 do not have a parent with the disorder and represent
new genetic changes. All persons with NF2--those with affected parents
and those without--have a 50-50 risk that each one of their children
will be affected. Disorders such as NF2 which affect both sexes
equally and are passed from an affected person to 50% of their children
are termed autosomal dominant disorders. Recently the
exact piece of genetic material which causes NF2 was identified
on chromosome 22. This identification has made it possible to find,
by a blood test , if a relative of a person with NF2 also
has NF2. Just like surgery, genetic testinghas both risks
and benefits and should be discussed thoroughly with your health
Many individuals and families with
NF2 have found it helpful to seek the advice of a multi-disaplanary
NF clinic. Peer support groups may provide practical advice
and support to augment professional providers skills . Finally,
several other web sties and resources
may provide helpful information.
Figure 5. Spinal cord tumor. Patients with NF2 often develop
tumors within their spinal cord (ependymomas and astrocytomas)
especially in the neck region (labeled with a * in this figure).
In patients without NF2, such tumors are always removed immediately,
but if a patient has NF2 it may be more prudent to watch such
tumors closely and only intervene when neurological symptoms
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