Syringomyelia
Chiari Malformation | Medical Disclaimer
What is Syringomyelia?
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Syringomyelia 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.
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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.
What causes Syringomyelia?
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.
What are the different forms of Syringomyelia?
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.
How is Syringomyelia diagnosed?
Physicians now use magnetic resonance imaging (MRI) to diagnose Syringomyelia.
The MRI is 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.
How is Syringomyelia treated?
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
non-communicating 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.
Information reprinted from National
Institute of Neurological Disorders and Stroke(NINDS)
