A synovial cyst of the spine is a fluid-filled sac that develops along the spine. It’s the result of degeneration of a facet joint of the vertebrae of the spine. Most synovial cysts develop in the portion of the lower spine called the lumbar spine.
These cysts are uncommon and in many cases produce no symptoms. The cysts aren’t deadly or cancerous. They may, however, cause issues with your spine like spinal stenosis.
Spinal stenosis is narrowing or shrinking of the spinal column. Pressure can increase on the spinal cord and the nerves inside the column as the open space inside the spinal column decreases. Symptoms increase as pressure increases. Symptoms of spinal stenosis include pain and cramping in the back and legs. The discomfort is often worse if you stand for a long period of time.
As a facet joint in your spine breaks down it can produce more fluid than a healthy joint. The fluid is useful for the damaged joint. It provides extra lubrication and helps ease the joint’s movements, but a cyst may develop in response to the extra fluid. As the fluid builds it can get caught in the synovial lining of the joint. Eventually a cyst may form.
The fluid in the cyst is not dangerous. It’s not under any pressure and won’t cause any problems until it begins pushing on the spine. Even very large cysts are rarely problematic.
These cysts are most common in older people since they are the result of deterioration of the spine. It’s rare that someone under 50 will develop a synovial cyst.
A synovial cyst rarely causes noticeable or detectable symptoms until it becomes large enough to begin interrupting or interfering with the spine. At that point the cyst may start to cause symptoms of spinal stenosis.
Symptoms might include:
- pain in the lower back
- pain in one or both legs
- pain that radiates down the back of the leg and to the feet
- painful cramping in the legs
- numbness or tingling in one or both legs
- increased pain and symptoms when standing that relieves or eases when sitting
A synovial cyst is best seen with a magnetic resonance imaging (MRI) scan. This scan allows your doctor to see inside the spinal column and find any cysts or other explanations for your symptoms. Other imaging tests like an X-ray or ultrasound may also be able to detect the cyst.
If your doctor finds a cyst they may want to conduct additional scans to inspect the spine and spinal column for damage. It’s important for your doctor to assess if there is any damage to the spine. Also, your doctor will want to look for any instability issues and make a decision about surgery before removing the cyst.
Nonsurgical treatment options for a synovial cyst are described below.
Over-the-Counter Pain-Relief Treatments
Heat and cold therapy is one way you can reduce discomfort and pain caused by a cyst. Mild stretching and exercise may also be useful if done with doctor’s approval.
Mild pain medications like acetaminophen and ibuprofen can reduce pain caused by a cyst. Your doctor may prescribe a stronger medicine if your pain is particularly problematic or troubling.
Your doctor may suggest leaving the cyst alone if it isn’t causing any problems. The cyst might not grow large enough to cause problems or symptoms. If it does, you can revisit treatment options.
If you experience symptoms only with certain activities, like exercising or your job, your doctor can help you modify your activities and movements to reduce symptoms.
Two types of injections are used to treat synovial cysts. A facet injection can drain the fluid from the cyst through the facet joint. A steroid is inserted after the fluid is removed to help reduce swelling and inflammation. Another type of injection, an epidural steroid injection, may also be used to treat the pain caused by a synovial cyst. This common treatment doesn’t reduce or remove the cyst. Instead, this injection aims to reduce the pain caused by the cyst. This pain relief is temporary and you may need additional treatments to maintain the effect.
If these conservative nonsurgical treatments don’t work or are not an option for you, your doctor may recommend surgery to remove the cyst altogether. The surgery isn’t very difficult. It will require some recuperation time. But newer surgery techniques have limited the size of the incision that is needed to remove the cyst. That cuts down on pain and recovery time.
When to Be Concerned
Synovial cysts are rarely dangerous. In some cases, a condition called cauda equina syndrome may develop as a result of a synovial cyst. This syndrome is a very serious condition and requires emergency medical attention.
This syndrome affects the cauda equina (nerve roots) in the lumbar spine. You may lose sensation and the ability to move when these nerve roots become compressed. This condition may also impact other nerves, like those connected to the bowels and bladder. The damage may be permanent if this condition isn’t treated quickly. Recovering full function may be difficult if not impossible.
Ganglion vs. Synovial
Doctors can rarely tell the difference between a ganglion and synovial cyst with a naked eye. A ganglion cyst is a fluid-filled sac that often develops in the wrists and ankles.
It’s only when the cysts are removed and inspected that a difference can be detected. A synovial cyst has a thin film of tissue that encapsulates the cyst (synovium). A ganglion cyst doesn’t have this tissue.
Your doctor doesn’t need to distinguish between them since both are treated the same way. In fact, doctors rarely take the extra step to clinically diagnose the type of cyst you have once it’s removed.