Chronic back pain often severely limits daily activities and quality of life. When conservative treatments like physical therapy and oral medications fail, doctors may recommend a minimally invasive procedure known as a facet block. This procedure involves injecting medication near or directly into the spinal joints suspected of causing discomfort. This targeted approach helps both pinpoint the exact source of the pain and provide extended relief. Facet blocks are performed on an outpatient basis and are considered a relatively low-risk option for managing persistent neck or back pain.
Targeting the Facet Joints
The spine is composed of bony segments called vertebrae, and on the back of each vertebra are small, paired joints known as facet joints, or zygapophyseal joints. These joints act like hinges, providing stability to the spine while guiding and limiting movement. They are synovial joints, enclosed by a capsule and containing lubricating fluid, similar to the knee or hip joints.
Like other joints, facet joints can develop arthritis due to wear and tear, injury, or degenerative changes. When the cartilage breaks down or the capsule becomes inflamed, they become a significant source of pain. This inflammation irritates the tiny medial branch nerves that send pain signals from the joint to the brain. A facet block delivers a local anesthetic and a powerful anti-inflammatory steroid directly to the affected joint or the nerves that supply it, interrupting pain signals and reducing inflammation.
Diagnostic Tool Versus Pain Relief
Facet blocks serve two distinct purposes: diagnosis and treatment. The initial use is often diagnostic, intended to confirm whether the facet joint is the true source of the patient’s pain. For this purpose, the injection typically contains only a short-acting local anesthetic.
If the patient experiences immediate and substantial pain relief, it confirms the targeted facet joint is the source of the pain. This diagnostic information is crucial for planning subsequent, longer-term treatment. Once the diagnosis is confirmed, the block is used therapeutically, aiming for long-lasting pain reduction. A therapeutic block includes both the anesthetic for immediate numbing and a corticosteroid, a potent anti-inflammatory medication, to calm inflammation and provide sustained relief.
The Injection Procedure Explained
The facet block is a minimally invasive procedure typically performed in a clinic or outpatient setting, lasting approximately 15 to 30 minutes. The patient is positioned on the table, often lying on their stomach, and connected to monitoring equipment to track vital signs. The skin over the injection site is thoroughly cleaned with an antiseptic solution.
The physician first injects a small amount of local anesthetic to numb the skin and underlying tissue, which may feel like a brief sting. Next, a specialized imaging technique, such as fluoroscopy (real-time X-ray guidance) or CT, is used to ensure precise needle placement. This guidance allows the doctor to direct the thin needle to the exact facet joint or medial branch nerve being treated. Contrast dye is often injected to confirm the needle is correctly positioned before the final medication is delivered.
What to Expect After the Block
Following the procedure, patients are monitored briefly before discharge, and driving is not permitted for the rest of the day due to the local anesthetic. Immediate, significant relief from the anesthetic is common, but this effect is temporary and typically wears off within a few hours. Mild soreness or tenderness at the injection site is a normal side effect for a day or two.
The therapeutic effect of the corticosteroid is not immediate; it can take two to seven days to become noticeable as inflammation subsides. During this waiting period, some patients may temporarily feel an increase in their original pain. Relief from a successful therapeutic block can vary significantly, ranging from several weeks to many months. A follow-up appointment assesses the injection’s effectiveness, and if relief is substantial but short-lived, the physician may recommend additional treatments like physical therapy or radiofrequency ablation.