Synovial Cysts in the Spine
For patients with degenerative spinal conditions, one cause of their back pain may be synovial cysts. Synovial cysts are benign, fluid-filled sacs that develop in the facet joints of the lumbar spine (low back) as a result of degeneration. If large enough, these sacs can cause spinal stenosis; a narrowing of the spinal canal that places pressure on spinal nerves and causes pain.
What causes synovial cysts?
The synovium is a thin film of tissue that produces fluid to help lubricate the joints. When facet joints in the lumbar spine begin to degenerate, this fluid may build up in an attempt to protect the joint. In some patients, small amounts of the fluid escape from the joint capsule but remain within the synovium, creating a sac-like protrusion. These cysts are not under tremendous pressure and, even if quite large, rarely cause neurological problems or cauda equina (loss of bowel or bladder function).
Many older patients have synovial cysts in their lumbar spines but have no symptoms. Occasionally, however these cysts can cause pain in the lower back that travels down the legs. The pain is relieved when sitting as this position widens the spinal canal and relieves pressure on the nerves.
How are synovial cysts diagnosed?
A synovial cyst can be seen on a MRI. X-rays should also be done to determine the extent of the degeneration of the facet joints and to assess any other spinal conditions that can cause instability such as spondylolisthesis (when one vertebra slips forward onto another).
How are these cysts treated?
If the cysts are not causing any symptoms, no treatment except observation is needed. If the patient is experiencing mild discomfort, it may be advisable to simply restrict those activities that are the most uncomfortable. Pain relief medications, injections, and other conservative pain relief options such as physical therapy or chiropractic may also be helpful in relieving pain. However, if the patient's pain is severe, chronic, and interferes with their daily living activities, surgery may be necessary.
Minimally invasive spine surgical techniques may be used to treat synovial cysts. These procedures can be done using minimally invasive techniques and have a relatively short recovery time. However, there is the possibility that the cysts can re-form. Another option is to remove the cyst and fuse the joint in order to assure the cysts will not return. This is a more invasive procedure with a longer recovery time. Since every patient is different, a consultation with an experienced spine specialist is essential.