A variety of conditions can lead to damage to the facet joints, such as spinal stenosis or osteoarthritis, or from a trauma to the back, such as a car accident.
Studies have demonstrated that facet joint injury is responsible for the chronic neck pain of whiplash in 60% of those with persisting pain, and for chronic low back pain in 5 to 40% (depending on the study) of those with post-injury low back pain.
The nerves to the facet joints are termed the medial branch nerves and they transmit pain signals to the brain. It stands to reason that interrupting the nerves will stop the pain from facet joint injury or disease, even if the facet joints themselves cannot be healed.
Facet joint injection procedure
The facet joint injection procedure begins with the patient lying face down on the X-ray table.
The physician injects a local anesthetic, which numbs the skin and the tissue around the facet joint. Next, the physician uses X-ray guidance, called fluoroscopy, to direct a small needle over the medial branch nerves.
The needle tip position is usually checked in two different views (front to back and side to side) to confirm appropriate placement. Following this confirmation, a numbing medicine called a local anesthetic, is slowly injected onto each targeted nerve.
Typically two nerves carry pain sensations from each facet joint to the brain. Therefore two adjacent nerves must be frozen for each joint, and so if four joints are due to be anesthetized, eight nerves must be frozen.
Directly after the procedure, the patient records his/her pain score on a “pain scoring sheet” that will be given.
Every 15 minutes after the procedure the patient scores his/her pain score until two sheets are completed, about 4 hours.
If the facet joints on both sides were frozen, the patient may record the pain score for the left and right sides as different numbers. Also on these sheets, the patient may record medication usage and any other events that may occur within the 4-hour period such as a slip and fall.
For lumbar (low back) injections it is requested that the patient walk for 1 -2 minutes before recording a pain score every fifteen minutes after the injections.
If it takes more than 15 minutes to reach home please ask the driver to stop the car at a parking lot to allow the patient to walk 1 – 2 minutes before each pain score recording.
The patient will then return the completed sheets to the referring physician but should keep a copy for reference. These sheets contain the result of the test and it is important to retain these.
One cannot rely on one’s memory at a later date to determine if the test was positive or negative.
If the patient experiences significant pain relief immediately after the injection, the test is often repeated for confirmation.
A different local anesthetic may be used for the second test. Two positive tests indicate that the facet joint is the cause of the patient’s pain. The patient may then be referred for any of a number of facet joint treatments which are long-acting, although no known treatment will provide a cure.
The patient may be a candidate for a follow-up procedure called a facet joint nerve radiofrequency neurotomy (also termed rhyzotomy or denervation) that may provide longer pain relief.