Trigger Point Injection for Trapezius Muscle
Trigger point injections (TPIs) in the trapezius muscle are recommended only for temporary, symptomatic relief in selected patients with myofascial pain, as long-lasting benefit has not been demonstrated (Level II evidence). 1
Recommended Treatment Approach
Injection Technique
- Lidocaine (0.5%) is the preferred agent for TPIs in the trapezius muscle as it reduces the intensity and duration of post-injection soreness compared to dry needling 2
- It is essential to elicit local twitch responses (LTRs) during injection to obtain an immediate desirable effect 2
- Injections should be performed in the intramuscular innervation zone (IZ) of the trapezius muscle rather than just at the trigger points for better long-term pain relief 3
- Combined lidocaine injection therapy in both the mid-upper trapezius and lower trapezius is more effective than single-site injection 3
Frequency and Duration
- Once therapeutic effect is achieved, TPIs should not be repeated more frequently than once every 2 months 4
- Up to 4 sets of injections may be considered to diagnose pain origin and achieve therapeutic effect 4
- Additional sets of TPIs are not medically necessary if no clinical response is achieved from previous injections 4
Augmentation Techniques
- Adding ischemic compression (30 seconds) after TPI shows better effects than TPI alone 5
- Longer duration of ischemic compression (60 vs. 30 seconds) does not provide additional benefit 5
Expected Outcomes and Monitoring
Short-term Effects
- Immediate pain relief is expected in most patients without fibromyalgia 6
- Post-injection soreness (different from the original myofascial pain) may develop within 2-8 hours after injection 2
- Patients with concurrent fibromyalgia may experience delayed and attenuated pain relief compared to those with myofascial pain alone 6
Long-term Effects
- TPIs provide only short-term relief and are not recommended for long-term management of chronic pain 1
- Documentation of quantifiable improvement in pain scores, function, and duration of relief is necessary to establish medical necessity for any additional interventions 7
Safety Considerations
Precautions
- The lowest effective dose of lidocaine should be used to avoid high plasma levels and serious adverse effects 8
- Resuscitative equipment, oxygen, and other resuscitative drugs should be available for immediate use 8
- Careful monitoring of cardiovascular and respiratory vital signs is necessary after each injection 8
- Use with caution in debilitated, elderly patients, acutely ill patients, and those with hepatic or cardiovascular disease 8
Potential Adverse Effects
- Common: Post-injection soreness, subcutaneous hemorrhage 9
- Rare but serious: Methemoglobinemia, systemic toxicity, infection 8
Alternative and Adjunctive Treatments
When TPIs Are Ineffective
- Dry needling may be as effective as injections containing medications for myofascial pain 4
- Intramuscular stimulation techniques may provide more significant improvements in pain intensity and cervical range of motion than lidocaine injection 9
- Physical therapy focusing on stretching and strengthening exercises should be implemented as a first-line approach after failed TPI 7
Adjunctive Therapies
- Conservative measures (medication, therapeutic exercise, physical therapy) should be tried before receiving injections 4
- If conservative measures and injection therapies fail to provide adequate relief after 2-3 months, surgical evaluation may be considered 7
Common Pitfalls to Avoid
- Performing repeated injections without documenting quantifiable improvement in pain scores, function, and duration of relief 4
- Continuing the same intervention despite lack of documented significant improvement 4
- Not eliciting local twitch responses during injection, which is essential for immediate effectiveness 2
- Injecting only at the trigger points rather than in the intramuscular innervation zone, which may reduce long-term effectiveness 3