This procedure is performed for treatment of chronic low back pain that has not responded to conservative measures such as prolonged physical therapy and activity modifications. A trial injection called facet nerve injection is performed 1st at another setting. Facet nerve injection anesthetizes those points between the junction of transverse process and the pedicle where tiny nerves that are known cause of low back pain reside.
If patient receives excellent response to the facet nerve injection then the more permanent radiofrequency facet block is performed. The procedure is performed with patient awake using x ray control called fluoroscopy. Stimulation is performed prior to actual coagulation and this makes the procedure quite safe in terms of nerve injury even though this can still occur. Nerve injury is quite rare. The tip of the radiofrequency needle gets hot coagulating or denaturing the tiny nerve fibers that are the known causes of chronic low back pain. Sometimes the tiny nerve fibers grow back causing recurrent low back pain and some patients require yearly facet blocks if they receive excellent response after each one. Other risks of the procedure includes infection and allergic reactions to medications used.
The overall clinical success rate of the procedure is about 50% in those who has excellent response to trial local anesthetic injection. The procedure takes approximately half an hour and patients are not allowed to drive home so that they need to bring a driver.
Mild analgesics are prescribed such as Vicodin for a few days afterwards as they will be in some pain from the procedure itself. Return to work without any restriction is possible usually in a few days after the procedure. Whether the procedure is successful or not is not determined until about a few weeks after the procedure when the pain from the procedure itself goes away.
Indications to use a facet joint injection
A facet joint injection is perhaps the best way to diagnose facet joint syndrome. Joints that may look abnormal on an X-ray may in fact be painless, and joints that look fine may indeed be the source of the pain; only the injection tells the true story. These injections may be used to treat low back pain and determine whether the facet joints are the true culprits. It is also a rather simple procedure with low risk.