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$Title{Acoustic Neuroma}
$Subject{Acoustic Neuroma Acoustic Neurilemoma Neurinoma Schwannoma Bilateral
Acoustic Neuroma Neurofibroma Fibroblastoma, Perineural Cerebellopontine Angle
Tumor Neurofibromatosis Type 2 Bell's Palsy Tinnitus}
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Copyright (C) 1985, 1988, 1992, 1993 National Organization for Rare
Disorders, Inc.

45:
Acoustic Neuroma

** IMPORTANT **
It is possible that the main title of the article (Acoustic Neuroma) is
not the name you expected.  Please check the SYNONYMS listing to find the
alternate name and disorder subdivisions covered by this article.

Synonyms

     Acoustic Neurilemoma
     Neurinoma
     Schwannoma
     Bilateral Acoustic Neuroma
     Neurofibroma
     Fibroblastoma, Perineural
     Cerebellopontine Angle Tumor

Information on the following diseases can be found in the Related
Disorders section of this report:

     Neurofibromatosis Type 2
     Bell's Palsy
     Tinnitus

General Discussion

** REMINDER **
The Information contained in the Rare Disease Database is provided for
educational purposes only.  It should not be used for diagnostic or treatment
purposes.  If you wish to obtain more information about this disorder, please
contact your personal physician and/or the agencies listed in the "Resources"
section of this report.


Acoustic Neuroma is a benign (noncancerous) tumor of the 8th cranial
nerve.  This nerve lies within the ear (auditory) canal, and is associated
with hearing loss and sending balance information from the inner ear to the
brain.

Symptoms

The early symptoms of an Acoustic Neuroma include a ringing sound in the ear
(tinnitus) and/or a hearing loss.  These symptoms occur due to pressure from
the tumor on the 8th cranial nerve.

An Acoustic Neuroma may press or squeeze (compress) the facial nerve (7th
cranial nerve) resulting in facial muscle weakness.  The trigeminal nerve
(5th cranial nerve) is responsible for sensation on the skin of the face and
the surface of the eye; if the 5th cranial nerve becomes involved it may lead
to facial numbness.

An Acoustic Neuroma may also grow in the direction of the brain stem and
press on the rear portion of the brain (cerebellum).  This may result in an
impaired ability to coordinate muscle movement (ataxia) of the arms and legs.
Downward expansion of the tumor may produce numbness in the mouth, impaired
speech (dysphagia), and/or hoarseness.

The growth of an Acoustic Neuroma may increase pressure within the skull
(intracranial pressure) resulting in personality changes and an impaired
ability to think and reason.  Pressure may increase on the facial nerve
resulting in facial twitching and a lack of balance (asymmetry) to the face.
Sudden expansion of the tumor may be caused by excessive bleeding
(hemorrhage) and/or swelling due to an abnormal accumulation of fluid
(edema).

Causes

The exact cause of an Acoustic Neuroma is not known.  There appears to be an
hereditary predisposition in a small group of people who have Acoustic
Neuromas that grow on both sides of the head.

A genetic predisposition means that a person may carry a gene for a
disease but it may not be expressed unless something in the environment
triggers the disease.

Acoustic Neuromas can also occur as a symptom of Neurofibromatosis Type
II, which is a hereditary disorder characterized by multiple benign tumors.
(See related disorders section of this report.)

Affected Population

Small Acoustic Neuromas that produce no symptoms have been found on autopsy
in 2.4 percent of people in the United States.  It is estimated that the
occurrence of Acoustic Neuromas with symptoms ranges from 1 in 3,500 to 5 in
1,000,000 Americans.  More women are affected by an Acoustic Neuroma than
men.  An unusually large number of cases have been found in Humboldt County,
California.

Related Disorders

Symptoms of the following disorders can be similar to those of Acoustic
Neuroma.  Comparisons may be useful for a differential diagnosis:

Bell's palsy is a nonprogressive facial nerve disorder characterized by
sudden onset of facial paralysis.  The paralysis results from compression and
the excessive accumulation of blood around the 7th cranial (facial) nerve.
Early symptoms of Bell's Palsy may include a slight fever, pain behind the
ear, a stiff neck, and facial muscle weakness on one side of the face,
and/or facial stiffness.  Symptoms may begin very suddenly or over the course
of several hours and sometimes follows exposure to cold or a draft.  Part or
all of the face may be affected.  (For more information on this disorder,
choose "Bell's Palsy" as your search term in the Rare Disease Database).

Neurofibromatosis Type 2 is a rare inherited disorder characterized by
bilateral (both sides) Acoustic Neuromas, the appearance of brown spots
(cafe-au-lait macules) on the side and fibrous tumors (neurofibromas) on the
skin.  This disorder may also be associated with tumors in the brain, spinal
cord and other areas of the body.  Major symptoms may include a buzzing or
ringing sound in the ears (tinnitus) and eventual loss of hearing.  (For more
information on this disorder, choose "Neurofibromatosis" as your search term
in the Rare Disease Database).

Tinnitus is a person's subjective experience of sound that does not exist
in the environment.  The sounds of Tinnitus have been described as clicking,
buzzing, whistling, ringing and/or roaring.  These sounds may always be
present, or they may come and go.  Tinnitus is frequently associated with a
loss of hearing.  (For more information on this disorder, choose "Tinnitus"
as your search term in the Rare Disease Database.)

Therapies:  Standard

At the present time, the only curative treatment for Acoustic Neuroma is
surgical removal of the tumor.  The location and size of the tumor determine
the direction that the surgeon uses to enter the skull and remove the tumor
(suboccipital or translabyrinthine).   Postoperative problems may include:
headache, obstruction or leakage of fluid that surrounds the brain and spinal
cord (cerebrospinal fluid), inflammation of the membranes that surround the
brain (meningitis), and/or decreased mental alertness due to development of a
blood clot or obstruction of flow of cerebrospinal fluid.  Large Acoustic
Neuromas may have to be operated on and removed in stages requiring more than
one operation.

The removal of an Acoustic Neuroma is a complex and delicate process.  In
general, the smaller the tumor at the time of surgery, the less chance of
complications.  As the tumor enlarges, the incidence of complications becomes
greater.  Therefore, there may be problems after surgery related to the
cranial nerves that may or may not have been present before the tumor was
removed.  In general, surgery for Acoustic Neuromas is performed on people
between 30 and 60 years of age.

People with an Acoustic Neuroma may have a complete or partial loss of
hearing generally caused by a medium or large tumor, particularly if the
tumor extends into the brain.  It may be possible to preserve hearing,
however, if the tumor is smaller than 0.6 inches.  Close monitoring of
hearing function during surgery may reduce the possibility of hearing loss.

A ringing sound in the ear (tinnitus) may continue after surgery for the
removal of an Acoustic Neuroma.  Occasionally tinnitus may remain the same as
before surgery.  In a few cases tinnitus begins only after the removal of the
tumor.

The facial nerve may be damaged by the Acoustic Neuroma or as a result of
surgery.  In some cases it may be necessary for the surgeon to remove
portions of the facial nerve, resulting in temporary or permanent facial
paralysis.  The regrowth of the nerve (regeneration) and restoration of
function to the muscles of the face may take up to a year.  If the facial
paralysis persists, a second surgery may be performed to connect the healthy
portion of the facial nerve to the hypoglossal nerve in the neck.  This may
bring some improvement in function to the muscles of the face.  There are
also other surgical procedures to aid in reanimating the sagging face.
Continued facial paralysis may cause food to "get lost" in the mouth on the
affected side which may eventually cause dental problems.

Eye problems may develop in approximately 50 percent of patients
following surgical removal of an Acoustic Neuroma.  Double vision (diplopia)
may occur if there is pressure on the 6th cranial nerve and there may be
impairment of the muscles of the eyelids.  Artificial tears or eye lubricants
may be needed.

A portion of the 8th cranial nerve that is associated with balance is
often removed during surgery for Acoustic Neuroma resulting in unsteadiness
and dizziness.  However, balance may gradually improve with time if the
normal ear compensates for the loss.

Therapies:  Investigational

Surgical techniques for the removal of Acoustic Neuroma are improving
dramatically and research is continuing on the development of safer and more
effective procedures and rehabilitation after surgery.

Another treatment for Acoustic Neuroma, being developed in Sweden, is the
use of a special form of radiation therapy.  At the present time, the long
term benefits and the risks of side effects from radiation are not known.

The Epidemiology Branch of The National Institute of Deafness and other
Communication Disorders (NIDCD) is conducting research on inherited bilateral
Acoustic Neuromas.

This disease entry is based upon medical information available through
January 1993.  Since NORD's resources are limited, it is not possible to keep
every entry in the Rare Disease Database completely current and accurate.
Please check with the agencies listed in the Resources section for the most
current information about this disorder.

Resources

For more information on Acoustic Neuroma, please contact:

     National Organization for Rare Disorders (NORD)
     P.O. Box 8923
     New Fairfield, CT  06812-1783
     [phone]

     Acousitic Neuroma Association
     P.O. Box 12402
     Atlanta, GA 30355
     [phone]

For Acoustic Neuroma associated with Neurofibromatosis contact:

     National Neurofibromatosis Foundation, Inc.
     141 Fifth Ave.
     New York, NY  10010
     [phone]

     and

     Neurofibromatosis Inc.
     3401 Woodridge Ct.
     Mitchellville, MD  20716
     [phone]

     American Tinnitus Foundation
     P.O. Box 5
     Portland, OR  97207
     [phone]

     Alexander Graham Bell Association for the Deaf
     3417 Volta Place, N.W.
     Washington, DC  20007
     [phone]

     Deafness Research Foundation
     55 East 34th Street
     New York, NY  10016
     [phone]

     NIH/National Institute of Deafness & Other Communication Disorders
     (NIDCD)
     9000 Rockville Pike
     Bethesda, MD  20892
     [phone]

References

THE MERCK MANUAL 15th ed.:  R. Berkow, et al:  eds; Merck, Sharp & Dohme
Research Laboratories, 1987.  P. 2190.

MENDELIAN INHERITANCE IN MAN, 8th ed.:  Victor A. McKusick; Johns Hopkins
University Press, 1986.  P. 9.

CECIL TEXTBOOK OF MEDICINE, 19th Ed.:  James B. Wyngaarden, and Lloyd H.
Smith, Jr., Editors; W.B. Saunders Co., 1990.  Pp. 2108, 2112, 2219.

PRINCIPLES OF NEUROLOGY, 4th Ed.; Raymond D. Adams, M.D. and Maurice
Victor, M.D., Editors; McGraw-Hill Information Services Company, 1989.  Pp.
538-539.

CONSERVATIVE MANAGEMENT OF ACOUSTIC NEUROMAS:  J.M. Nedzelski; Otolaryngol
Clin North Am (Jun 1992; 25(3)).  Pp. 691-705.