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Syringomyelia
(sear-IN-go-my-EEL-ya) is a disorder in which a cyst forms within
the spinal cord. This cyst, called a syrinx, expands and elongates
over time, destroying the center of the spinal cord. Since the
spinal cord connects the brain to nerves in the extremities, this
damage results in pain, weakness, and stiffness in the back,
shoulders, arms, or legs. Other symptoms may include headaches and a
loss of the ability to feel extremes of hot or cold, especially in
the hands. Each patient experiences a different combination of
symptoms.
Other, more common disorders
share the early symptoms of syringomyelia. In the past, this has
made diagnosis difficult. The advent of one outpatient test,
however, called magnetic resonance imaging (MRI), has significantly
increased the number of syringomyelia cases diagnosed in the
beginning stages of the disorder.
About 21,000 American men and
women have syringomyelia, with symptoms usually beginning in young
adulthood. Signs of the disorder tend to develop slowly, although
sudden onset may occur with coughing or straining. If not treated
surgically, syringomyelia often leads to progressive weakness in the
arms and legs, loss of hand sensation, and chronic, severe pain.
A watery, protective
substance known as cerebrospinal fluid normally flows around the
spinal cord and brain, transporting nutrients and waste products. It
also serves to cushion the brain.
A number of medical
conditions can cause an obstruction in the normal flow of
cerebrospinal fluid, redirecting it into the spinal cord itself. For
reasons that are only now becoming clear, this results in syrinx
formation. Cerebrospinal fluid fills the syrinx. Pressure
differences along the spine cause the fluid to move within the cyst.
Physicians believe that it is this continual movement of fluid that
results in cyst growth and further damage to the spinal cord.
Generally, there are two
forms of syringomyelia. In most cases, the disorder is related to an
abnormality of the brain called a Chiari I malformation, named after
the physician who first characterized it. This anatomic abnormality
causes the lower part of the cerebellum to protrude from its normal
location in the back of the head into the cervical or neck portion
of the spinal canal. A syrinx may then develop in the cervical
region of the spinal cord. Because of the relationship that was once
thought to exist between the brain and spinal cord in this type of
syringomyelia, physicians sometimes refer to it as communicating
syringomyelia. Here, symptoms usually begin between the ages of 25
and 40 and may worsen with straining or any activity that causes
cerebrospinal fluid pressure to fluctuate suddenly. Some patients,
however, may have long periods of stability. Some patients with this
form of the disorder also have hydrocephalus, in which cerebrospinal
fluid accumulates in the skull, or a condition called arachnoiditis,
in which a covering of the spinal cord--the arachnoid membrane--is
inflamed.
The second major form of
syringomyelia occurs as a complication of trauma, meningitis,
hemorrhage, a tumor, or arachnoiditis. Here, the syrinx or cyst
develops in a segment of the spinal cord damaged by one of these
conditions. The syrinx then starts to expand. This is sometimes
referred to as noncommunicating syringomyelia. Symptoms may appear
months or even years after the initial injury, starting with pain,
weakness, and sensory impairment originating at the site of trauma.
The primary symptom of
post-traumatic syringomyelia is pain, which may spread upward from
the site of injury. Symptoms, such as pain, numbness, weakness, and
disruption in temperature sensation, may be limited to one side of
the body. Syringomyelia can also adversely affect sweating, sexual
function, and, later, bladder and bowel control.
Some cases of syringomyelia
are familial, although this is rare. In addition, one form of the
disorder involves a part of the brain called the brainstem. The
brainstem controls many of our vital functions, such as respiration
and heartbeat. When syrinxes affect the brainstem, the condition is
called syringobulbia.
Physicians now use magnetic
resonance imaging (MRI) to diagnose syringomyelia. The MR imager
takes pictures of body structures, such as the brain and spinal
cord, in vivid detail. This test will show the syrinx in the spine
or any other conditions, such as the presence of a tumor. MRI is
safe, painless, and informative and has greatly improved the
diagnosis of syringomyelia.
The physician may order
additional tests to help confirm the diagnosis. One of these is
called electromyography (EMG), which measures muscle weakness. The
doctor may also wish to test cerebrospinal fluid pressure levels and
to analyze the cerebrospinal fluid by performing a lumbar puncture.
In addition, computed tomography (CT) scans of a patient's head may
reveal the presence of tumors and other abnormalities such as
hydrocephalus.
Like MRI and CT scans,
another test, called a myelogram, takes x-ray-like pictures and
requires a contrast medium or dye to do so. Since the introduction
of MRI this test is rarely necessary to diagnose syringomyelia.
Surgery is usually
recommended for syringomyelia patients. The main goal of surgery is
to provide more space for the cerebellum (Chiari malformation) at
the base of the skull and upper neck, without entering the brain or
spinal cord. This results in flattening or disappearance of the
primary cavity. If a tumor is causing syringomyelia, removal of the
tumor is the treatment of choice and almost always eliminates the
syrinx.
Surgery results in
stabilization or modest improvement in symptoms for most patients.
Delay in treatment may result in irreversible spinal cord injury.
Recurrence of syringomyelia after surgery may make additional
operations necessary; these may not be completely successful over
the long term.
In some patients it may be
necessary to drain the syrinx, which can be accomplished using a
catheter, drainage tubes, and valves. This system is also known as a
shunt. Shunts are used in both the communicating and
noncommunicating forms of the disorder. First, the surgeon must
locate the syrinx. Then, the shunt is placed into it with the other
end draining cerebrospinal fluid into a cavity, usually the abdomen.
This type of shunt is called a ventriculoperitoneal shunt and is
used in cases involving hydrocephalus. By draining syrinx fluid, a
shunt can arrest the progression of symptoms and relieve pain,
headache, and tightness. Without correction, symptoms generally
continue.
The decision to use a shunt
requires extensive discussion between doctor and patient, as this
procedure carries with it the risk of injury to the spinal cord,
infection, blockage, or hemorrhage and may not necessarily work for
all patients.
In the case of trauma-related
syringomyelia, the surgeon operates at the level of the initial
injury. The cyst collapses at surgery but a tube or shunt is usually
necessary to prevent re-expansion.
Drugs have no curative value
as a treatment for syringomyelia. Radiation is used rarely and is of
little benefit except in the presence of a tumor. In these cases, it
can halt the extension of a cavity and may help to alleviate pain.
In the absence of symptoms,
syringomyelia is usually not treated. In addition, a physician may
recommend not treating the condition in patients of advanced age or
in cases where there is no progression of symptoms. Whether treated
or not, many patients will be told to avoid activities that involve
straining.
The precise causes of
syringomyelia are still unknown. Scientists at the National
Institute of Neurological Disorders and Stroke in Bethesda,
Maryland, and at grantee institutions across the country continue to
explore the mechanisms that lead to the formation of syrinxes in the
spinal cord. For instance, Institute investigators have found that
as the heart beats, the syrinx fluid is abruptly forced downward.
They have also demonstrated the presence of a block to the free flow
of cerebrospinal fluid that normally occurs in and out of the head
during each heartbeat.
Surgical techniques are also
being refined by the neurosurgical research community. In one
treatment approach currently being evaluated, neurosurgeons perform
a decompressive procedure where the dura mater, a tough membrane
covering the cerebellum and spinal cord, is enlarged with a graft.
Like altering a suit of clothing, this procedure expands the area
around the cerebellum and spinal cord, thus improving the flow of
cerebrospinal fluid and eliminating the syrinx.
It is also important to
understand the role of birth defects in the development of hindbrain
malformations that can lead to syringomyelia. Learning when these
defects occur during the development of the fetus can help us
understand this and similar disorders, and may lead to preventive
treatment that can stop the formation of many birth abnormalities.
Dietary supplements of folic acid during pregnancy have already been
found to reduce the number of cases of certain birth defects.
Diagnostic technology is
another area for continued research. Already, MRI has enabled
scientists to see conditions in the spine, including syringomyelia,
even before symptoms appear. A new technology, known as dynamic MRI,
allows investigators to view spinal fluid pulsating within the
syrinx. CT scans allow physicians to see abnormalities in the brain,
and other diagnostic tests have also improved greatly with the
availability of new, non-toxic, contrast dyes. Patients can expect
even better techniques to become available in the future from the
research efforts of scientists today.
The National Institute of
Neurological Disorders and Stroke conducts and supports a wide range
of research on neurological disorders, including pain and painful
disorders such as syringomyelia. For more information on this and
other neurological disorders, or on the Institute and its research
programs, contact the Institute's Brain Resources and Information
Network (BRAIN) at:
BRAIN
P.O. Box 5801
Bethesda, Maryland 20824
(301) 496-5751
(800) 352-9424
www.ninds.nih.gov
*The organization listed
below provides printed information and assistance to syringomyelia
patients and other interested individuals.
American Syringomyelia
Alliance Project, Inc.
P.O. Box 1586
Longview, Texas 75606-1586
(903) 236-7079
1-800-ASAP-282
www.asap4sm.com/
Syringomyelia
