INTRODUCTION

Syringomyelia is a disorder in which a cyst forms within the spinal cord. This cyst, called a syrinx, expands and elongates over time, destroying a portion of the spinal cord from its center and expanding outward. When a syrinx widens enough to affect nerve fibers that carry information from the brain to 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 depending on where in the spinal cord the syrinx forms and how far it expands.

Other, more common disorders share the early symptoms of syringomyelia. In the past, this has made diagnosis difficult. But the widespread availability of an outpatient imaging procedure called magnetic resonance imaging (MRI) has significantly increased the number of syringomyelia cases diagnosed as an incidental finding or as the consequence of regional spine imaging.

There are many causes of syrinx formation in the spinal cord.  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. Symptoms usually begin between the ages of 25 and 40 and may worsen with straining or any activity that causes CSF 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 CSF accumulates in the skull, or a condition called arachnoiditis, in which a covering of the spinal cord--the arachnoid membrane--is inflamed.

Other causes of syringomyelia result from 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 non-communicating 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 occur on one or both sides of the body. Syringomyelia can also adversely affect sweating, sexual function, and, later, bladder and bowel control.