A syrinx is a fluid-filled cyst that is characteristic of syringomyelia and syringobulbia. Syringomyelia is a disorder in which a syrinx forms within the spinal cord. Syringobulbia occurs when the cyst extends to involve the brainstem. Syringomyelia usually presents first, but isolated cases of syringobulbia have been documented.
A syrinx forms when cerebrospinal fluid—the fluid that surrounds and cushions the brain and spinal cord—accumulates within the spinal cord itself. A number of medical conditions can obstruct the normal flow of cerebrospinal fluid, causing the redirection of excess fluid into the spinal cord. As a syrinx expands and elongates over time, it can cause various symptoms and irreversible damage to the spinal cord.
How common is syrinx?
Estimates of the number of Americans with syringomyelia vary widely, but a conservative estimate is that about 40,000 people in the United States are affected. Improved diagnostic imaging has significantly increased the number of cases detected in the early stages of the disorder.
Who gets syrinx?
Symptoms caused by a syrinx usually present in early adulthood. In most cases, a syrinx is related to Arnold Chiari I malformation—a condition in which brain tissue extends into the spinal canal. Congenital malformations, which are present from birth, are much more common than acquired malformations.
Other risk factors for developing a syrinx include spinal cord trauma, a spinal cord tumor, meningitis, hemorrhage, and arachnoiditis.
How is syrinx diagnosed?
A syrinx can be detected with diagnostic imaging, such as magnetic resonance imaging (MRI) and computed tomography (CT).
Symptoms caused by a syrinx may vary depending on where in the spinal cord the cyst forms and how far it extends. Symptoms usually progress slowly, although coughing or straining may trigger sudden onset.
Symptoms of syringomyelia may include:
- Progressive weakness in the arms and legs
- Stiffness in the back, shoulders, arms, or legs
- Loss of reflexes
- Loss of sensitivity to pain and temperature
- Bowel and bladder dysfunction
Symptoms of syringobulbia may include:
- Dizziness (vertigo)
- Involuntary rapid movement of the eyeballs (nystagmus)
- Loss of sensitivity to pain and temperature on one or both sides of the face
- Speech problems
- Unsteady walk (gait instability)
- Ringing in the ears (tinnitus)
These symptoms are shared with other medical conditions. Contact a medical professional if you are having symptoms.
If a syrinx is not causing problems, monitoring the cyst may be all that is necessary. However, surgery may be recommended if you are having symptoms. The goal of surgery is to remove the pressure the syrinx is placing on the spinal cord and restore the normal flow of cerebrospinal fluid. This may help alleviate symptoms and improve neurological function. The type of surgery performed depends on the underlying cause and the location of the syrinx.
If the cyst is associated with Chiari malformation, a neurosurgeon may perform a suboccipital craniectomy. This procedure involves enlarging the opening at the base of the skull and expanding the outermost covering of the brain, which is called the dura mater.
In other cases, a shunt may be used to drain fluid from the syrinx. One end of a flexible tube is placed in the cyst and the other is placed in a cavity, usually the abdomen, where the fluid can be drained.
If the syrinx is caused by a tumor, surgically removing the tumor may restore the normal flow of cerebrospinal fluid and allow fluid to drain from the syrinx.
In trauma-related cases, the preferred surgical approach is to operate at the level of the initial injury to expand space around the spinal cord and decrease fluid volume. This operation is performed outside of the spinal cord.
- Date of last review: January 24, 2017