If not treated surgically, syringomyelia often leads to progressive weakness in the arms and legs, loss of hand sensation, and chronic, severe pain. 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. 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.