Syringomyelia

Syringomyelia (pronounced suh-rin-go-my-EE-lee-uh) is a medical condition in which a fluid-filled cyst forms inside the spinal cord. Syringomyelia occurs when the flow of cerebrospinal fluid around the brain and spinal cord becomes blocked. A few congenital disorders are risk factors for developing syringomyelia, although spinal injuries and certain illnesses may also cause it. Doctors typically use magnetic resonance imaging (MRI) or computerized tomography (CT) scans to diagnose syringomyelia. Treatments vary depending on symptoms and underlying cause.

Background

Syringomyelia is a rare condition in which a fluid-filled cavity or cyst, called a syrinx, forms within the spinal cord. The syrinx may grow and lengthen over time, causing damage to the center of the spinal cord. Other names for syringomyelia are hydromyelia, syringohydromyelia, or spinal cord cyst. Syringomyelia may result from a congenital birth defect, a spinal cord injury, and even certain illnesses. The condition most often presents in adults between the ages of twenty and forty, but it can develop in young children and older adults.

The word syringomyelia is derived from the Greek words syrinx, meaning "tube" or "fistula," and muelos, meaning "marrow." French doctor Charles Estienne first described syringomyelia in the sixteenth century, although he did not call it by its modern name at that time. Another French doctor, Charles Prosper Ollivier d'Angers, gave syringomyelia its name in 1824. Two American doctors, Robert Abbe and William Bradley Coley, receive credit for conducting the first surgery to drain a syrinx within the spinal cord in 1892.

Overview

Syringomyelia results from the blocked flow of cerebrospinal fluid. Cerebrospinal fluid is a clear liquid that typically flows around the brain and spinal cord. In surrounding the brain and spinal cord, cerebrospinal fluid helps cushion and protect them. When something blocks the flow of cerebrospinal fluid, some of the fluid may enter the spinal cord and form a syrinx. Left unchecked, the syrinx can expand over time and cause a variety of symptoms.

Some patients with syringomyelia develop pain and muscle weakness, especially in the back, shoulders, arms, and legs. Sometimes atrophy, or muscle deterioration, can occur. Patients who have muscle weakness or atrophy may have trouble walking. They may experience sudden muscle contractions or twitches. Patients may develop numbness or tingling in their limbs, and they may become less sensitive to pain and temperature. Facial pain and numbness are associated with syringomyelia in some cases. Other common symptoms include scoliosis, or a curvature of the spine, and incontinence, or difficulty controlling bowel and bladder movements. Some people with syringomyelia experience no symptoms at all. Severe cases, however, can lead to paralysis.

People with Chiari malformation are at increased risk of developing syringomyelia. Chiari malformation is a congenital birth defect that occurs at the point where the brain and spinal cord meet. Normally the cerebellum, a part of the brain located near the base of the skull, and the brain stem are situated above an opening in the base of the skull called the foramen magnum. In people with Chiari malformation, the cerebellum and brain stem get pushed downward into the foramen magnum. This puts pressure on the cerebellum and brain stem that can block the flow of cerebrospinal fluid and lead to the development of syringomyelia. At least 50 percent of syringomyelia cases are associated with Chiari malformation.

People with spina bifida also are at increased risk of developing syringomyelia. Spina bifida is a congenital birth defect that results when a developing fetus's spinal cord fails to develop properly. Some people with spina bifida have tethered spinal cord syndrome, which is caused when tissues connected to the spinal cord restrict movement. Tethered spinal cord syndrome increases the risk of developing syringomyelia.

Non-congenital risk factors for syringomyelia include spinal cord injuries, hemorrhage, arachnoiditis, meningitis, and tumor. A spinal cord injury is any trauma to the spinal cord. A hemorrhage is bleeding in the spinal cord. Arachnoiditis is swelling of the arachnoid. The arachnoid is the middle membrane of the three membranes that surround the brain and spinal cord. Meningitis is an infection in one of the membranes surrounding the brain and spinal cord. The bacterial form of meningitis is more serious than the viral form and can be fatal. A tumor is an abnormal growth of tissue. A tumor may be benign (not cancerous) or malignant (cancerous). All of these can restrict the flow of cerebrospinal fluid and lead to the formation of a syrinx in the spinal cord.

Doctors usually use MRI scans to diagnose syringomyelia. MRI scans use radio waves and a magnetic field to create detailed pictures of structures inside the body. If a doctor suspects syringomyelia, he or she may conduct an MRI scan of the spine and spinal cord. Doctors also may use CT scans. Like an MRI scan, a CT scan creates a detailed picture of structures inside the body. However, it involves taking a series of X-rays from different angles rather than radio waves and a magnetic field.

Once a doctor has diagnosed a patient with syringomyelia, he or she may recommend a number of treatment options that depend on the patient's symptoms. Patients who are experiencing no symptoms may not require any treatment. For people with Chiari malformation, doctors may perform surgery to enlarge the opening at the base of the skull. This relieves the pressure on the cerebellum and the brain steam, and returns the flow of cerebrospinal fluid to normal. If a tumor is blocking the flow of cerebrospinal fluid, the doctor may remove the tumor. For a person with tethered spinal cord syndrome, the doctor may perform surgery to release the tethered spinal cord. In rare cases, doctors may insert a tube called a shunt to drain fluid from the syrinx into a body cavity outside the spinal column (such as the abdomen). However, shunts can cause some dangerous side effects, such as hemorrhage and infection. In addition, they can move out of place or become blocked.

Patients who undergo surgery usually must take a course of antibiotics to prevent infection in the spinal cord after the surgery. People who experienced muscle weakening or atrophy may enter physical therapy to regain muscle strength. Because syringomyelia can recur after treatment, doctors typically monitor patients, using periodic MRI and CT scans to evaluate and track the size of the syrinx.

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