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The Expert Advisor
Post-Traumatic Syringomyelia
By James W. Little, MD, PhD, Associate Professor
in the Department of Rehabilitation Medicine at the University of
Washington, and Assistant Chief of the Spinal Cord Injury Service at
the VA Puget Sound Health Care System
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Originally published in the Fall 1998 issue of Spinal
Cord Injury Update.
Syringomyelia is an uncommon but disabling
complication of SCI. Although more than half of all people with
SCI develop a cyst in the spinal cord at the injury site, only
about 4% develop syringomyelia, in which the cyst fills with fluid
and expands. This enlarged cyst, or syrinx, can damage the spinal
cord and cause pain, loss of sensation, or weakness. Other
symptoms may include low blood pressure with light-headedness,
sweating, increased or decreased spasms, and impaired bladder
emptying. In some cases, syringomyelia results in major loss of
function.
Syrinxes (the dark area in the center of the spinal cord, which
is a lighter grey, shown at right) form when the normal flow of
cerebrospinal fluid is obstructed by either a bony narrowing of
the spinal canal or the presence of scar tissue at the injury
site. Coughing, sneezing, bearing down, or lifting a heavy weight
may contribute to syrinx development because these activities
increase pressure in the veins, forcing fluid into the cyst.
Spinal fluid is thought to flow through channels that act as
one-way valves: fluid flows in but little flows out. Pressure
builds in the syrinx until it enlarges and ruptures, damaging
normal spinal cord tissue and injuring nerve cells.
Syrinxes are diagnosed by magnetic resonance imaging (MRI),
but patients can often detect the presence of a syrinx by
testing themselves for loss of pin-prick and temperature
sensation, which are early signs of syringomyelia.
Quantitative strength tests and nerve conduction tests are
useful for monitoring syrinx status and assessing the
effectiveness of treatments. Nerve conduction tests can also
help detect other causes of neurologic decline that may mask
or occur simultaneously with a syrinx, such as carpal tunnel
syndrome, other peripheral nerve entrapment, or spinal cord
impingement.
Surgery is often used to prevent syrinxes from expanding. A
shunt tube can be placed in the syrinx to drain fluid into the
abdominal cavity. In a dural graft procedure, the space around
the spinal cord is enlarged to allow free flow of fluid and
reduce pressure. A cordectomy involves cutting across the
spinal cord and opening up the syrinx to release fluid. All of
these surgical procedures have risks and limitations, and none
is ideal in patients with incomplete injuries and preserved
motor function below the syrinx because of the risk that the
surgery may result in the loss of some or all of this
function. Although shunts are standard treatment in patients
with complete injuries, there is a risk that the shunt tube
will occlude (close up) and the syrinx will reaccumulate
fluid, resulting in further neurologic decline. In some
patients who receive dural grafts, symptoms worsen despite the
surgery. Patients should continue to be closely monitored
after surgery for signs of further neurological decline.
Non-operative treatments for syringomyelia usually result
in only modest and temporary improvements. Water pills and
vasoconstrictor medications may help reduce fluid formation
around the spinal cord. Avoiding activities that increase
venous pressure - high force and breath-holding exercises, a
head-down position, and bending the trunk so the chest rests
on the thighs - may reduce the risk of syrinx expansion. Quad
coughing, in which a care giver compresses the abdomen during
an attempted cough to improve its effectiveness, may cause
pressure in the inferior vena cava (a large vein in the
abdomen) that can be transmitted to the syrinx. To avoid
direct pressure on this vein, compressions can be performed to
one side of the center of the abdomen. Draining the syrinx
with a needle can also yield temporary benefits, but fluid
tends to reaccumulate. Treatments currently available are most
useful for preventing further neurologic decline but may also
improve strength and decrease pain.
Syrinxes and their symptoms vary a great deal from patient
to patient. Weakness and pain may or may not be present, and
weakness can develop rapidly or gradually. Patients with
syringomyelia often need a wide range of rehabilitation
services to help them manage pain and adjust to new weakness
or loss of function. Regular follow-up with a rehabilitation
practitioner experienced in the long-term management of
syrinxes is essential in order to monitor symptoms, guide
treatments, and prevent neurologic decline.
Reprinted with permission from Spinal Cord Injury Update,
the newsletter of the Northwest
Regional Spinal Cord Injury System (University of
Washington Department of Rehabilitation Medicine, Box 356490,
Seattle, WA 98195-6490; 206/685-3999).
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