A synovial cyst is most commonly found in patients who are older than 65 years old. This type of cyst is benign (non-malignant), and the symptoms may remain stable and not progress for long periods of time.
Synovial Cyst Symptoms
The patient's symptoms will depend largely on the cyst's size, position, and how it is impacting the surrounding neural structures.
Typical symptoms will usually include one or a combination of the following:
- Lower back pain may or may not be present
- Lumbar radiculopathy, or leg pain (also called sciatica). The leg pain may occur in one or both legs, and may radiate down the back of the leg and into the foot.
- Typically, there is minimal or no pain if the patient is seated, because in the seated position the spinal canal opens up and there is not as much pressure on the spinal nerves. When standing up straight or walking, however, the spinal canal closes down and creates more pressure on the nerves.
- Neurological deficits, which may include numbness or tingling, or muscle weakness, in one or both legs. Weakness may include foot drop.
- Neurogenic claudication, which usually presents as a painful, cramping feeling in the legs
Rarely, cauda equina syndrome can develop as a result of a synovial cyst, which is a serious condition that requires immediate medical attention.
Synovial Cyst Diagnosis
The synovial cyst is best visualized on an MRI scan of the spine. It shows up as a hyperintense lesion that has the same signal intensity as water.
X-rays, including flexion/extension motion x-rays, are also important to rule out any spinal instability. It is important to check for spinal instability because the joint is undergoing degeneration, and there is often an accompanying degenerative spondylolisthesis (vertebral body that slips forward), which indicates that the joint is unstable and incompetent.
It is very important to identify any instability before surgery for the synovial cyst, because if the instability is not addressed at the time of surgery, a revision surgery will often be required at a later date.