Causes of Syringomyelia
Chiari Malformation Type 1
The most common condition associated with syringomyelia is the Chiari malformation type I. It is believed that crowding of tissue from the cerebellum located at the opening of the base of the skull can cause spinal fluid blockage. As a result, fluid builds up within the spinal cord. When Chiari malformation is associated with syringomyelia, surgery usually is recommended to create more space at the base of the skull and upper neck.

Spinal Tumor
In some cases, a tumor within the spinal cord can physically block the flow of fluid in the central canal. This type of syrinx generally is treated by surgical removal of the tumor.

In rare circumstances, physicians are unable to pinpoint the specific cause of syringomyelia. In this situation, neurosurgeons insert a small drainage tube into the syrinx cavity to allow the fluid to drain directly to a space outside of the spinal cord. While this treatment does not address the underlying cause of the condition, it usually relieves symptoms.

Spinal Cord Trauma
Trauma to the spinal cord is the third most common cause of syringomyelia. When the trauma is low level (e.g., the mass of a bulging disk creating compression of the spinal cord which reacts by forming a syrinx), treatment involves surgery to remove the compressing mass. In the case of severe spinal cord injury leading to paralysis of the legs or arms and legs, there currently is no standard treatment specifically for the syrinx.

Spina Bifida
The second most common cause of a syrinx in the spinal cord is Spina Bifida (myelodysplasia). Tension related to tethering of the bottom or the middle of the spinal cord leads to a stretch injury that can then obstruct the flow of fluid within the central canal of the spinal cord. This produces the fluid backup seen in syringomyelia. This type of syrinx is best treated with surgery to untether the spinal cord.