Facet Joint Diagnostic Blocks help the physician confirm where a pain generator is located. The fluoroscope (X-Ray) machine enables the physician to place the needle precisely into the facet joint. Once the needle is in place local anesthetic and a small amount of steroid medication are injected into each facet joint. This procedure takes about 20-30 minutes. The patient’s report regarding the effectiveness of the block (e.g. decrease of pain; ability to increase activity in the first few hours after the procedure) is important information. The physician will ask questions about the patient’s pain immediately after the procedure has been completed and again at the post-procedure visit. Generally, diagnostic blocks only provide pain relief for up to 6 hours after the procedure. Note: this procedure is diagnostic, not therapeutic, so the pain relief is temporary. However, even if the patient receives only a few hours of pain relief it confirms that the procedure was successful in blocking a pain generator. Diagnostic blocks are designed to help the physician determine what the next step will be in the treatment decision.
This procedure may create mild soreness at the injection site, but patients, generally, report no significant discomfort after this procedure. Patients rarely, if ever, need pain medication after this procedure. If the patient is taking pain medication, we would prefer that intake be decreased or stopped 24 hours prior to the procedure and limit the use for 24 hours after the procedure.
Facet joints are small joints located in pairs at the back of the spine. They provide stability and guide motion in the mid back. If the joints become painful they may cause pain in the mid back, ribs, chest or abdomen. The lumbar facet joints are paired synovial joints that are a potential source of chronic low back pain. As obvious as this seems to most pain specialists it is not a uniformly accepted statement. Facet joints, also called zygapophysial joints, apophyseal joints, or posterior intervertebral joints, are synovial joints that allow for motion of the spine. In the lumbar spine, they allow for flexion and extension (bending forward and backward.) Facet joints are present at every level of the spine from the neck down. The configuration of the joints is different at different levels of the spine reflecting their different functions at each level.
While facet joints as a source of back pain are somewhat controversial what is clear is that these joints have a rich nerve supply and are certainly capable of producing pain when injured or when inflamed. It is interesting that few physicians will contest the potential of synovial joints elsewhere in the body (such as a knee joint) as being capable of hurting, but some physicians still argue against facet joints in the spine as being sources of chronic back pain. Part of the controversy surrounds the difficulty in diagnosing facet joint pain. Imaging studies such as x-ray and MRI often do not correlate with clinical symptoms reported by the patient. It is commonly observed that patients with x-ray changes suggestive of advanced arthritis in the facet joints do not always report pain, and patients with no apparent arthritic changes on x-ray sometimes do report pain with no obvious cause.
Because of the inadequacy of diagnostic imaging studies to predict whether facet joints may be a source of pain it is felt by most pain specialists that the only true way to diagnose facet joint pain is to perform controlled anesthetic blocks to the facet joints or to the nerves supplying the facet joints. If these joints are determined to be a source of pain for the patient as indicated by relief of pain with anesthetizing the joint then prolonged pain relief can often be achieved with the radiofrequency destruction of the nerves to these joints.
Facet joint pain can be suspected in patients with complaints of low back pain with vague referral patterns into the hips, buttocks, upper thighs and groin. The pain is often described as aching and is associated with stiffness, restricted range of motion, and possibly muscle spasms in the low back. Patients may have discomfort with both leaning backward and bending forward. They are commonly tender to palpation over the lower back just to the side of the midline.
Facet joints can be directly injected with local anesthetic agents (numbing medication) or with steroids for an anti-inflammatory effect. The concept of facet joint injection with steroid is identical to the concept of injecting an inflamed, arthritic, and painful knee joint with steroids. Diagnostic injections of local anesthetics directly onto the facet joint nerves can be done to see if this relieves pain. When injecting the nerves with local anesthetic drugs pain relief will be of short duration, on the order of hours. The purpose of doing diagnostic facet nerve blocks is to see if destruction of these nerves might result in prolonged pain relief. Once it has been established that pain relief is reliably attained by anesthetizing the facet nerves a destructive procedure to the nerve is carried out by using radiofrequency needles. Radiofrequency is a method of destroying nerves with a specialized needle that heats the nerve tissue.
A facet joint injection serves several purposes. First, by placing numbing medicine into the joint, the amount of immediate pain relief experienced will help confirm or deny the joint as a source of pain. Additionally, the temporary relief of the numbing medicine may better allow a chiropractor or physical therapist to treat that joint. Also, time-release cortisone (steroid) will help to reduce any inflammation that may exist within the joint(s).
When is a facet joint nerve block indicated?
Patients with chronic back pain that is primarily axial back pain and that have not responded to simple treatment interventions with anti-inflammatory medication and physical therapy. The physical examination may reveal tenderness to palpation in the lower back and pain with bending forward and back. There should not be any unexplained neurological deficit.
Before the Procedure
If a patient is an insulin-dependent diabetic, they must not change their normal eating pattern prior to the procedure. Patients may take their routine medications. (i.e. high blood pressure and diabetic medications). Patients should not take pain medications or anti-inflammatory medications the day of their procedure. Patients have to be hurting prior to this procedure. They may not take medications that may give pain relief or lessen their usual pain. These medicines can be restarted after the procedure if they are needed.
During the Procedure
Relaxation medication is given through an IV. The patient is placed on the fluoroscopy table; face down so that the doctor can best visualize these joints in the back using fluoroscopic guidance. The skin is scrubbed using two types of sterile scrub (soap). Next, the physician numbs a small area of skin with numbing medicine. This medicine stings for several seconds. After the numbing medicine has been given time to be effective, doctor directs a very small needle using fluoroscopic guidance into the joint space. Then, a small mixture of numbing medicine (anesthetic) and anti-inflammatory (cortisone/steroid) is injected. One or several joints may be injected depending on the location of the patient’s usual pain.
After the Procedure
Immediately after the procedure, the patient can move around and may try to imitate something that would normally bring about his or her usual pain. The patient then reports the degree of pain relief (using our usual 0-to-10 scale) and records the relief the patient experiences during the next week on a post-injection evaluation sheet (“pain diary”). The diary is given to the patient when the patient is released to go home. The patient is asked to bring or mail this completed “pain diary” to SPS.
The patient will not be able to drive the day of the procedure. The patient’s chest or mid-back may feel weak or numb for a few hours.
The patients will be in recovery at SPS’s in-office facility approximately 2 – 3 hours for their procedure. Patients need to bring a driver with them. Patients may return to their normal activities the day after the procedure, including returning to work.
Potential complications of facet joint injections
The following are potential complications following a facet joint injection: Infection, injury to nerve roots, accidental spinal injection, allergic or adverse reaction to the injected drugs, and bleeding.