A synovial cyst is a rare growth that occurs as a result of degeneration in the spine. Because these fluid filled sacs develop in areas where spinal degeneration has occurred, they often don’t appear in patients under the age of 40. The cysts can expand and put pressure on different spinal structures, leading to pain and discomfort. Today, we take a closer look at the causes, symptoms and treatment options of synovial cysts.

Causes and Symptoms of Spinal Synovial Cysts

As we mentioned above, synovial cysts form as the result of spinal degeneration, but they typically only form in the lumbar portion of the spine. Oftentimes the cysts form at the L4-L5 level, but once in a while they occur at the L3-L4 level. This is how the cysts are thought to develop:

1. The facet joints in the lumbar spine are comprised of two separate surfaces covered with cartilage.
2. This cartilage facilitates movement, but as degeneration occurs, the area loses its frictionless surface.
3. Also inside the joint is the synovium membrane, which is a thin film of tissue that helps to further lubricate the joint.
4. When the joint degenerates, the synovium produces more fluid to help compensate, and cysts can form due to this extra fluid in the joint.

Symptoms of synovial cysts vary depending on their size and relation to surrounding structures, but the most common symptoms include:

• Low back pain or discomfort
• Leg weakness
• Pain when walking that subsides when seated or lying down
• Numbness
• Cramping in the legs
• Cauda equina syndrome

Diagnosis and Treatment of Synovial Cysts

Synovial cysts are best diagnosed with the assistance of an MRI scan. This type of scan can reveal the presence fluid filled sacs. An MRI scan may also be combined with an X-ray to determine if the stability of the spine has been affected. Determining the extent of spinal instability is crucial during the diagnosis stage as failing to understand the extent of the damage can lead to the need for a revision surgery.

There are a number of surgical and non-surgical options available to treat a synovial cyst.

• Observation/Activity Modification – If the cyst is present but not causing any or much pain, doctors may recommend a period of rest, observation, activity modification and exercise.
• Pain Medications – NSAIDs and pain medications can help manage minor discomfort caused by synovial cysts.
• Injections – Facet joint injections and epidural steroid injections can drain the cyst and keep pain at bay.
• Surgery – If conservative treatment fails, surgery may be necessary. The most common surgical operations include microdecompression spine surgery and a decompressive spinal fusion operation.’

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