Musculoskeletal pain is a common ED presentation and emergency providers can often manage it with NSAIDs alone.1 On the other hand, when patients present with small localized areas of intense muscle spasm called trigger points, NSAIDs won’t cut it. A trigger point injection (TPI), however, is a safe and easy way to treat the underlying cause of trigger point pain, and requires only basic equipment already available in most the EDs.
Trigger Points and Myofascial Pain Syndrome
Trigger points are the hallmark of Myofascial Pain Syndrome (MPS), an under-recognized condition that is characterized by musculoskeletal pain that is worse with movement, has a component of referred or regional pain, and involves palpable trigger points.2,3 These focal areas of hyper-irritable muscle spasm can feel like taut bands, nodules, or “knots” within skeletal muscle. Trigger points are exquisitely tender and palpation should fully reproduce a patient’s pain. Common etiologies include repetitive micro-trauma, chronic musculoskeletal disorders, and acute myofascial injury.4
A thorough history and physical exam is paramount in diagnosis, as there is no validated imaging modality or diagnostic testing that reliably detects the presence of trigger points.5,6 Identifying a discrete trigger point requires clear communication with patients during the exam. Although an injured muscle group may have global spasm and pain, a discrete trigger point will be significantly more tender in a small localized area when compared to the surrounding tissue.
Evidence for Trigger Point Injections
A TPI is the ideal management strategy when attempting to treat focal, hyper-irritated muscle spasm like trigger points. Most systemic analgesics including NSAIDs, muscle relaxants, and opioids provide only suboptimal pain relief.3 Non-pharmacological interventions such as physical therapy, nerve stimulation, acupuncture, and osteopathic manipulative therapy may provide short term analgesia, but these interventions are difficult to perform in the ED and lack long-term efficacy studies.6–8
In the acute care setting, dry needling or a TPI is a more practical approach to managing MPS and trigger points, and within the scope of emergency physicians to perform. The intervention involves the injection of local anesthetic, and treats the root cause of pain via mechanical inactivation of spasm. The local anesthetic serves only to block the discomfort of muscular manipulation with a needle; compared to TPIs, patients who receive dry needling alone have shown greater intensity and longer duration of post-injection soreness.9 Other injected substances have been studied, including lidocaine with steroids, botulinum toxin, and normal saline, however these have shown no significant analgesic benefit over local anesthetic alone.9–18
Drawing by Dr. Anisha Malhotra
Materials and Technique
TPIs require the following equipment:
- 22 or 25- gauge needle with syringe
- 1-2 mL local anesthetic (lidocaine 1-2% or bupivacaine 0.25-0.5%)
- Alcohol swab
It is important to ensure that the needle is long enough to penetrate the trigger point. A length of 1.5 inches or more will usually suffice, however a longer needle (~2.5 inches) may be required if the trigger point is located deep within a muscle.7,19,20
- Clean the area around the trigger point with alcohol.
- “Pinch” or immobilize the trigger point with your non-dominant hand.
- Insert the needle at a 30 degree angle, deep enough to engage the trigger point. Patients may experience a twitch response when the needle enters the trigger point. This is pathognomonic for the presence of a trigger point, but not required for identification.
- Slowly remove the needle almost all the way out of the skin before re-directing it into another quadrant. Move the needle in a NORTH, SOUTH, EAST, and WEST direction 1-2 times to ensure all areas of spasm have been inactivated.
- Prior to removing the needle, gently aspirate then infiltrate 1-2 mL of local anesthetic into the center of the spasm.
- Apply band-aid.
The patient should have significant improvement in pain upon re-evaluation. If there is no improvement, a second injection is not recommended. Discharged patients should be instructed to stretch the affected muscle and remain active, but avoid excessive use of the injected muscle group for approximately 72 hours.19
Contraindications, Complications, & Documentation
The contraindications to TPIs include overlying cellulitis at the desired injection site and allergy to local anesthetic.
Caution should be taken when injecting over the apices of the lungs or around the intercostal spaces. Additionally, it is imperative to remove the needle almost all the way out of the tissue before redirecting to avoid hematoma or breaking the needle.19
Lastly, a TPI is a billable procedure, with specific CPT codes, and can be performed by any licensed provider. Reimbursement requires documentation of:
- Dry needling
- Infiltration of local anesthetic
- The presence of a “trigger point” or “local muscle spasm” on physical exam
The Bottom Line
Trigger point injections are a safe and effective way to treat myofascial pain and its associated trigger points in the ED. In most cases, pain resolves or significantly improves with little to no additional analgesics. There procedure is quick and easy to perform, requires minimal equipment, and should be part of an opioid-sparing strategy for focal musculoskeletal pain.