Trigger point injections (TPIs) are a common method used to treat myofascial pain, which is pain originating from the muscles and their surrounding fascia. A trigger point is defined as a hyperirritable spot, felt as a palpable nodule or “knot,” located within a taut band of skeletal muscle fibers. These spots can be spontaneously painful or sensitive only to compression, and often produce referred pain to other areas of the body. TPIs are a therapeutic approach designed to inactivate the trigger point, thereby relieving localized pain and increasing the muscle’s range of motion. The mechanical and chemical disruption helps to break the pain-tension cycle, allowing the muscle fibers to relax and improving blood flow.
Identifying the Target Area
The process begins with a careful physical examination to precisely locate the trigger point before any injection is administered. The healthcare provider must locate the taut band of muscle fibers, which feels harder than the surrounding tissue. By palpating along this band, the clinician identifies the point of maximum tenderness, which is the actual trigger point.
Applying firm pressure often elicits a “jump sign,” which is an involuntary flinching or withdrawal by the patient, and a local twitch response within the muscle. This characteristic twitch confirms the precise location of the hyperirritable spot and guides the practitioner to the correct injection site. Patient positioning is crucial, as the muscle must be relaxed for accurate palpation and comfort during the procedure. Once identified, the trigger point is stabilized by pinching it between the clinician’s fingers to prevent it from rolling away during needle insertion.
Steps of the Injection Procedure
With the patient positioned and the target area confirmed, the skin overlying the trigger point is thoroughly cleansed with an antiseptic solution to minimize the risk of infection. The clinician isolates the trigger point, often holding it between the index finger and thumb, and inserts a thin needle at an acute angle, typically around 30 degrees to the skin. Before injecting any substance, the practitioner must aspirate the syringe to confirm the needle is not inside a blood vessel, a standard safety precaution.
The goal is to physically disrupt the muscle fibers using a technique known as “pistoning” or multiple penetrations. The needle is rhythmically inserted and retracted, without completely withdrawing it from the muscle, and redirected into adjacent tender areas. This mechanical agitation continues until the muscle twitching subsides or the taut band feels relaxed, providing a physical method to inactivate the trigger point.
A small volume of solution, typically a local anesthetic like lidocaine or bupivacaine, is injected into the site, usually between 0.2 to 2 milliliters total, often using a fanning technique. The anesthetic helps interrupt the nerve signals and the pain-spasm cycle. Sometimes a small dose of corticosteroid is added to reduce local inflammation, though this is less common. After the needling and injection are complete, direct pressure is immediately applied over the site for a minute or two to prevent bruising and bleeding.
Immediate Post-Injection Care and Response
Immediately following the procedure, patients may experience mild soreness or tenderness at the injection site, which is normal and manageable with over-the-counter pain relievers. The local anesthetic provides immediate numbness and pain relief, lasting for a few hours, though the full therapeutic effect develops later. Applying a cold pack to the treated area can help reduce temporary swelling or bruising.
The practitioner encourages gentle, active stretching of the treated muscle immediately after the injection while the anesthetic is active. This window of numbness allows for pain-free movement, helping the muscle regain its full range of motion. Patients are advised to avoid strenuous activities or heavy lifting for the first 24 to 48 hours to allow the muscle to recover.
Follow-up and Expected Results
The initial pain relief from the local anesthetic is temporary, but the sustained therapeutic effects become noticeable within 24 to 72 hours as the muscle begins to fully relax. A successful outcome includes a sustained reduction in pain, increased muscle range of motion, and improved function. Full pain relief may take a few days to a week to manifest completely.
TPIs are most effective when integrated into a comprehensive pain management plan. Combining the injection with physical therapy, stretching exercises, and addressing underlying postural issues is necessary to achieve long-term relief and prevent recurrence. Pain relief typically lasts for several weeks. The need for repeat injections is determined by the patient’s ongoing symptoms. If pain returns, a provider may recommend additional injections, often spaced every four to six weeks, to continue breaking the cycle of chronic muscle tension.