An Overview of Spinal Synovial Cysts

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Spinal synovial cysts occur when the synovial fluid (the fluid that normally lubricates the inner lining of joints) pressure builds up and causes part of the joint capsule to bulge. This is usually a result of degenerative changes or trauma. These cysts are not uncommon, and they usually don't cause symptoms for most people.

Spinal synovial cysts typically develop in the facet joints, which are the junctions that keep the vertebrae (spinal bones) interlocked. They can occur anywhere in the spine, and most of them occur in the lumbar region (low back).

Vertebral column
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Symptoms

For most people, synovial cysts won't cause any symptoms. If a synovial cyst is compressing a nerve, it can cause back pain, weakness, or numbness.

Synovial cysts can affect one side of the spine or both, and they can occur at one spinal segment or at multiple levels. The severity of symptoms depends on the size and location of a cyst.

Most of the time cysts cause radiculopathy due to irritation of a spinal nerve.

Effects of a synovial cyst can include:

  • Radiculopathy symptoms can develop if the cyst or inflammation from the cyst comes into contact with a spinal nerve root. This can cause sciatica, weakness, numbness, or difficulty controlling specific muscles. 
  • Neurogenic claudication (impingement and inflammation of spinal nerves) causes cramping, pain, and/or tingling in the low back, legs, hips, and buttocks.
  • If the spinal cord is involved, it may cause myelopathy—problems with the spinal cord resulting in numbness and weakness, and issues with balance.
  • Rarely, symptoms related to cauda equina, including bowel and/or bladder problems, progressive leg weakness, and saddle anesthesia (loss of sensation in the inner thighs, buttocks, and perineum) can occur.

Synovial cysts in the mid-back and neck are rare. When they do occur, thoracic synovial cysts and cervical synovial cysts may cause a range of symptoms, such as numbness, tingling, pain, or weakness.

Causes

Spinal synovial cysts are generally caused by degenerative changes like osteoarthritis that may develop in a joint over time.

With wear and tear, facet joint cartilage (the springy material in a joint that provides protection and shock absorption) erodes. In the process, the synovium may form a cyst.

Traumas both large and small have degenerative and inflammatory effects on joints as well, which may result in the formation of a synovial cyst.

About a third of patients who have a spinal synovial cyst also have a condition known as spondylolisthesis, which is when a lower vertebra slips forward onto the bone underneath it. It's thought that spondylolisthesis causes synovial cysts to form due to decreased stability in the facet joint.

Instability can occur at any area of the spine, but L4-5 is the most common level. If instability occurs, a cyst can develop. However, it is important to note that cysts can form without instability.

Diagnosis

Cysts are generally diagnosed via magnetic resonance imaging (MRI). They can also sometimes be seen with ultrasound, X-ray, or computed tomography (CT) scan.

Treatment

Some cysts remain small and cause few, if any, symptoms. Cysts only need treatment if they are causing symptoms.

Lifestyle Changes

Your healthcare professionals may suggest that you avoid certain activities that aggravate your symptoms.

You might be advised to stretch and to begin exercises that do not exacerbate your condition. Physical therapy or occupational therapy may also be recommended.

Intermittent use of over-the-counter nonsteroidal anti-inflammatories (NSAIDs) like Advil (ibuprofen) and Aleve (naproxen) may help relieve occasional pain.

Outpatient Procedures

For cysts that cause significant pain, numbness, weakness, and other issues, an aspiration procedure to drain fluid from the cyst can be beneficial.

In one study, researchers found that the success rate for these procedures ranges from 0 percent to 50 percent. People who undergo aspiration often need repeat procedures if the fluid build-up returns.

Epidural corticosteroid injections can reduce inflammation and may be a suitable option to relieve significant pain. It's recommended that patients receive no more than three corticosteroid injections per year.

Surgical Options

For more severe or persistent cases, doctors may recommend decompression surgery to remove the cyst and surrounding bone, which should relieve pressure on the nerve root.

There are several surgical options that range from minimally invasive endoscopic procedures to larger, open surgeries. The best surgical option for each patient varies based on the severity of their situation and whether associated disorders are present.

Surgical options include:

  • Laminectomy: Surgical removal of the bony structure that protects and covers the spinal canal (lamina)
  • Hemilaminectomy: A modified laminectomy procedure where a smaller portion of the lamina is removed
  • Facetectomy: To accompany laminectomy or hemilaminectomy, removal of part of the affected facet joint where the synovial cyst is located
  • Fusion of the facet joints and vertebra: Decreases mobility in the area,

Most people experience immediate pain relief following a laminectomy or hemilaminectomy. Fusion can take six to nine months to fully heal.

If surgery is performed without fusion of the joints where the cyst originated, the pain may return and another cyst may form within two years.

These surgeries are not without risk. Complications may include infection, bleeding, and injury to the spinal cord or nerve root.

A Word from Verywell

If a spinal synovial cyst is causing symptoms, there are treatments that can help. If your cyst isn't causing symptoms, your doctor will follow up with you to monitor for signs of degenerative disc disease, spinal stenosis, or cauda equina syndrome.

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4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Wilby MJ, Fraser RD, Vernon-roberts B, Moore RJ. The prevalence and pathogenesis of synovial cysts within the ligamentum flavum in patients with lumbar spinal stenosis and radiculopathy. Spine. 2009;34(23):2518-24. doi:10.1097/BRS.0b013e3181b22bd0.

  2. Kim DS, Yang JS, Cho YJ, Kang SH. Acute myelopathy caused by a cervical synovial cyst. J Korean Neurosurg Soc. 2014;56(1):55-7. doi:10.3340/jkns.2014.56.1.55

  3. Epstein NE, Baisden J. The diagnosis and management of synovial cysts: Efficacy of surgery versus cyst aspiration. Surg Neurol Int. 2012;3(Suppl 3):S157-66. doi:10.4103/2152-7806.98576

  4. Epstein NE, Baisden J. The diagnosis and management of synovial cysts: Efficacy of surgery versus cyst aspirationSurg Neurol Int. 2012;3(Suppl 3):S157-66. doi:10.4103/2152-7806.98576

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