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.

Magnetic Resonance Imaging (MRI) has significantly increased the number of syringomyelia cases diagnosed in the beginning stages of the disorder. 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. In most cases, the disorder is related to a congenital abnormality of the brain called a Chiari I malformation. This malformation occurs during the development of the fetus and 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.

Syringomyelia may occur as a complication of trauma, meningitis, hemorrhage, a tumor, or arachnoiditis. Symptoms may appear months or even years after the initial injury, starting with pain, weakness, and sensory impairment originating at the site of trauma. Some cases of syringomyelia are familial, although this is rare.