Continuous pain in the neck or the back may have several factors together. The facet joint is one source of pain along the axis, but degeneration in imaging is met often even in people who have no symptoms. The history, the physical examination, or an image alone therefore cannot confirm which joint is the root cause of the pain.
Facet joint and medial branch nerve procedures is a collective term for several kinds of procedure that have different purposes. It should not be explained as a single injection that diagnoses the root cause, reduces inflammation, releases fascia, reduces compression of the nerves, and guarantees long-term recovery all at once.
Pain from the facet is a clinical hypothesis, not a diagnosis from an image
Symptoms suspected of coming from the facet are usually in the neck or the back and may radiate to the neighbouring area. Arching or twisting the body may trigger the symptoms, but these characteristics are not specific. If the pain radiates down the arm or the leg together with weakness, numbness, or a change in reflexes, compression of a nerve root or another cause should be assessed.
An urgent assessment should be received when there is a severe accident, fever or illness throughout the body, a history of cancer together with new pain, unintended weight loss, night pain that is deteriorating quickly, neurological abnormality increasing, numbness in the area of the buttocks or the genitals, or a change in the control of continence. Injection should not delay the examination for a fracture, infection, cancer, compression of the spinal cord, or cauda equina syndrome.
Back pain that has no dangerous features does not need imaging as a routine. Imaging suits cases where a severe state or another cause is suspected, or where the result will change the plan of treatment. Finding a degenerated facet joint in an image does not prove that that joint is the root cause of the pain.
Each kind of procedure is different
The medial branch nerve block
A block for diagnosis or for predicting the result is the injection of a small amount of local anaesthetic near the medial branch nerves that supply the selected facet joints. If the pain decreases temporarily while doing activities that used to trigger the symptoms, it may increase the confidence that these nerves are sending the pain signal, and help select patients for nerve ablation. This procedure is not an injection of medicine into the joint, and a positive result is not a complete diagnosis, because there are both false positives and false negatives.
The injection of medicine into the facet joint
The intra-articular injection is the delivery of medicine into the inside of the facet joint. Local anaesthetic, corticosteroid, or both may be used according to the indications and the guidelines of practice. The evidence for injection to treat non-specific lower back pain as a routine gives inconsistent results. NICE does not recommend spinal injection to manage lower back pain, while the recommendations and the criteria for reimbursement differ according to the country and according to the position, neck or waist.
Nerve ablation with radiofrequency
Nerve ablation uses thermal energy on the selected medial branch nerves in order to reduce the sending of the pain signal for a period. NICE recommends considering it in selected people who have chronic localised lower back pain, for whom non-surgical care has not yet worked, and who respond positively to a diagnostic block. The result and the length of time of improvement differ, and the symptoms may return when the nerves recover.
Guidance by imaging and precision
Facet procedures should use suitable image guidance. Fluoroscopy is usually used in nerve blocks and in ablation, because the bony targets can be seen and the spread of the contrast medium can be checked. CT is used in some situations. Ultrasound has no ionising radiation and may suit targets in some positions when done by someone with experience, but it cannot always show the spread of the contrast medium or injection into a blood vessel.
A systematic review of 2022 from 7 studies found a pooled risk difference of 11% for incorrect needle placement in ultrasound-guided medial branch nerve blocks in the lumbar area, when verified with fluoroscopy or CT. Image guidance should therefore be chosen according to the position in the spine, the shape of the patient, the target, the equipment, and the expertise. It should not be said that they can be used interchangeably in every case.
The benefits, the limitations, and the risks
A diagnostic block has the goal of giving information in the short term, not of being a permanent treatment. An injection for treatment or nerve ablation may reduce pain in selected patients, but does not repair the degeneration of the spine, put right posture or "muscle imbalance", release fascia, or prevent recurrence. Pain and the ability to do activities should be recorded with the same indicators before and after the procedure.
Adverse symptoms may include temporary pain, bruising, numbness, weakness, dizziness, fainting, bleeding, infection, an allergic reaction, and effects from the medicine. Complications that are met infrequently but are severe are unintended injection into a blood vessel or into the cerebrospinal fluid space, toxicity from the local anaesthetic, injury to a nerve, puncture of the dura, or infection of the spine. Those using anticoagulants or antiplatelet medicines, those who have allergies, are pregnant, have diabetes, have low immunity, have an infection, or have had a procedure before, must receive an assessment specific to the individual, and should not stop their medicines by themselves.
If after the procedure there is new severe weakness, being unable to control continence, fever, increasing redness or swelling, a severe headache related to posture, difficulty breathing, or pain increasing rapidly, urgent medical advice should be received.
Rehabilitation is still the important heart of it
Before the procedure, most patients should receive suitable information, support to keep moving, and exercise that increases in level according to their capability and goals. Sleep, the burden of work, medicines, mood, fear of movement, and other factors may also need to be cared for. A block or ablation may open a period that helps in taking part in rehabilitation more, but does not take the place of rehabilitation.
The decision should cover the purpose of the procedure, the alternatives, the length of time expected, the uncertainties, the medicines used, the method of guidance, the follow-up plan, and what kind of result would change the next step.