There are three main treatment choices for synovial cysts in the lumbar spine:
Observation and activity modifications
Injections
Surgery
If the synovial cyst is not creating a lot of dysfunction or pain in the patient’s daily life, no medical treatments may be necessary. Since the pain is usually caused by certain positions, changing positions is a reasonable way to deal with the pain as long as a patient can still function adequately.
For exercise, it may be preferable for the patient to try stationary biking instead of walking, because in the seated position the patient should be fairly comfortable.
There are two types of injections that can be helpful to alleviate the pain: facet injections or epidural injections.
Facet injection. The facet joint can be entered with a small needle and occasionally the cyst can be drained by aspirating it through the joint. Afterwards, the joint is then injected with steroid to decrease inflammation.
Epidural steroid injection. The more common injection technique is to inject around the cyst with steroid in the epidural space (an epidural injection). It does not reduce the cyst but can reduce the pain.
Although the mechanism of the pain reduction is not well understood it is thought to be due to a reduction in inflammation. It works well about 50% of the time and not so well 50% of the time, and unfortunately, the pain relief tends to be temporary.
Still, even though either injection is not all that reliable in the long run it is reasonable to try since the only other alternative is surgery. Generally, no more than three injections within a year are recommended.
The most common kinds of spine surgery for synovial cysts can be either a decompression alone or a decompression with a spine fusion.
Microdecompression spine surgery
If there is no associated instability with the cyst (e.g. no degenerative spondylolisthesis as seen on flexion/extension x-rays) then a microdecompression of the nerve root with removal of the cyst is reasonable. Basically, this is the same approach as would be used for a microdiscectomy, and is a minimally invasive surgery with a relatively quick recovery. (See also Microdisectomy).
However, since the joint pathology (which caused the original synovial cyst) is still present the cyst can re-form at a later date.
Decompression with spine fusion surgery
The most reliable treatment method for a synovial cyst is to remove the cyst and then fuse the joint. Fusing the joint stops all the motion at that level, and without any motion the cyst should not regenerate.
This is the most reliable treatment, but it is also the most to go through. It changes the biomechanics in the back because one of the joints will no longer function. The L4-L5 level has the most motion, and fusing it creates more stress on the other non-fused levels of the lower spine. Also, the surgery is more to go through since this is an open procedure, and it takes about six to nine months or more for the fusion to heal. (See also Decompression surgery and Spine fusion surgery).
When deciding which treatment to pursue, patients need to base their decisions on three primary factors:
The amount of pain they are having
The length of time of their symptoms
The amount of dysfunction it causes in their life.
If the pain is relatively acute and tolerable, it is probably reasonable for the patient to modify his or her activities. If the pain is severe, then an injection might be more reasonable. If the pain is severe and has been going on for a while (e.g. years) or if the injections have not worked then surgery is more reasonable.
For younger more active patients, a trial of a microdecompression is probably a reasonable consideration (as long as there is no gross instability of the joints), with the knowledge that a fusion may be necessary in the future. For more elderly or less active patients, it may be more reasonable to jump to the definitive procedure of a fusion, since the stress transfer the fusion creates to the other joints is not as great in these patients and only one procedure would then be necessary.
Synovial cysts are an uncommon cause of lumbar stenosis, and the treatment is largely the same as for spinal stenosis with the exception that there is often accompanying spinal instability at the same joint that needs to be considered if surgery becomes necessary.
Surgery is only necessary for those patients that would like to do more activity with less pain. The surgery is very effective for treatment of this condition. The most successful surgery tends to be a decompression with a fusion (approximately a 90-95% success rate should be expected, which means a significant reduction in pain, not necessarily pain free), but this is also the treatment that is the hardest to go through and changes the biomechanics of the spine. It should be considered for people with moderate to severe activity limitations that have joint instability along with the cyst, and who have failed conservative treatments such as injections.
