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Study Summary
Background
Myofascial pain affects up to 85% of pain clinic patients and is characterized by painful trigger points in muscle. Two common injection treatments are used: local anesthetics (like lidocaine) and botulinum toxin-A (BTX-A). While both are widely used clinically, there has been no comprehensive comparison of their effectiveness. This creates uncertainty for doctors and patients about which injection type works better for myofascial pain.
What They Did
The researchers conducted a comprehensive systematic review and meta-analysis, searching three major medical databases for studies comparing local anesthetic and BTX-A injections for myofascial pain. They included 33 studies with various follow-up periods from immediately after injection up to 24 weeks later. The team analyzed pain intensity scores and compared effectiveness between the two injection types across different time periods, muscle locations, and treatment protocols.
What They Found
Local anesthetic injections consistently outperformed BTX-A injections for reducing pain intensity. Local anesthetics showed large effect sizes favoring treatment at 1-2 weeks, 3-4 weeks, 7-8 weeks, and 16 weeks after injection. BTX-A injections showed negligible or small effect sizes throughout most follow-up periods, only showing modest benefits at 18 and 24 weeks. Multiple sessions of local anesthetics were more effective than single sessions.
Local anesthetics worked particularly well in temporomandibular muscles and when used for widespread muscle pain. The analysis included over 1,000 patients across all studies.
What This Means
For patients with myofascial trigger points, local anesthetic injections appear to provide better and more consistent pain relief compared to botulinum toxin injections. The benefits of local anesthetics are seen quickly and last for several months. Multiple injection sessions may provide even better results. This evidence can help doctors make more informed treatment decisions and may lead to updated clinical guidelines.
However, the location of injection and individual patient factors may influence which treatment works best for each person.
- Studies Included
- 33
- Overall Effect Size at 3-4 weeks
- -0.37
- Statistical Significance
- p=0.02
1056
n=18
Various local anesthetic injections
n=16
Botulinum toxin-A injections
Local Anesthetic Studies
Various local anesthetic injections
BTX-A Studies
Botulinum toxin-A injections
Results Comparison
Effect Size at 3-4 Weeks
SMDKey Findings
| Finding | Detail | Impact |
|---|---|---|
| Local anesthetics showed large effect sizes for pain reduction at multiple time points | Significant benefits at 1-2 weeks (SMD -0.96), 3-4 weeks (SMD -1.01), and 16 weeks (SMD -1.33) | High |
| BTX-A injections showed minimal effectiveness throughout most follow-up periods | Negligible effect sizes until 18-24 weeks, with only modest benefits emerging later | High |
| Multiple local anesthetic sessions more effective than single sessions | Single session SMD -0.51 vs multiple sessions SMD -0.86, both favoring treatment | Medium |
| Location of injection influences effectiveness | Local anesthetics most effective in temporomandibular muscles (SMD -1.01) and widespread locations (SMD -1.41) | Medium |
| High heterogeneity between studies suggests variable treatment protocols | I² values >50% for most analyses, indicating significant differences in study methods and patient populations | Medium |
Strengths
- Comprehensive search of multiple databases with broad inclusion criteria
- Large number of included studies (33) with over 1,000 participants
- Rigorous methodology following PRISMA guidelines
- Multiple subgroup analyses examining different variables
- Long follow-up periods up to 24 weeks
Limitations
- High heterogeneity between studies limits generalizability
- Varied comparison groups including non-injection controls
- Limited to English language studies only
- Different local anesthetic types and concentrations used across studies
- Most BTX-A studies used single injection sessions only
Key Takeaways for Patients
What This Means for You
Local anesthetic injections appear more effective than botulinum toxin for trigger point pain
Pain relief from local anesthetics can be seen quickly and may last several months
Multiple injection sessions may provide better results than single treatments
The location of your trigger points may influence which treatment works best
Both injection types have been shown to be generally safe with temporary side effects
Read the Full Paper
Access the complete peer-reviewed study from Clinical Journal of Pain