Currentadvancesinthetreatmentofmyofascialpainsyndromewithtriggerpointinjections:Areview

Myofascial pain syndrome (MPS) is one of the most common causes of chronic musculoskeletal pain, yet it remains challenging to treat effectively. First defined by Travell and Simons in 1983, MPS arises from myofascial trigger points—highly irritable, palpable nodules within skeletal muscle or fascia that produce localized and referred pain when compressed. The condition affects a substantial portion of patients seeking pain care, with studies indicating that 85% of back pain and 54.6% of chronic head and neck pain may be attributable to MPS. Despite its prevalence, there is no universally accepted "gold standard" for diagnosis, and treatment approaches vary widely.

Among invasive options, trigger point injection (TPI) has emerged as one of the most popular and widely used clinical methods because it is relatively low-cost, minimally invasive, and can be targeted directly at the source of pain. This narrative review addresses the need for clinicians to understand the current evidence supporting different injectable agents and advances in delivery techniques for TPI.

The authors conducted a comprehensive narrative review of the literature on trigger point injection therapy for myofascial pain syndrome. They searched key databases including PubMed, Cochrane Library, and Google Scholar to gather peer-reviewed articles, systematic reviews, and meta-analyses. The review covered several major domains: objective diagnostic tools for identifying trigger points (surface electromyography, sonoelastography/shear-wave elastography, and infrared thermography); noninvasive treatment modalities as context (exercise therapy, dry needling, heat/cold therapy, ultrasound, TENS); and the core focus on TPI techniques and injectable agents. The review examined multiple injectable substances including glucose/prolotherapy solutions, normal saline, local anesthetics (particularly lidocaine), botulinum toxin type A, platelet-rich plasma, platelet-poor plasma, and corticosteroids.

For each agent, the authors summarized mechanism of action, key clinical studies, and comparative effectiveness data where available. They also evaluated ultrasound-guided injection techniques and compared TPI to alternative treatments such as dry needling.

The review identified several important findings across different injectable agents. For glucose injections (prolotherapy), concentrations ranging from 12.5% to 25% showed promising results: in one study of 45 patients, 80.0% reported more than 50% improvement in symptoms and the mean VAS score decreased from 7.0 to 2.44 (P < .001), representing a 65.0% reduction in symptom severity. Another study of 177 patients with 20% glucose injections showed significant relief with more than 80% of patients returning to daily activities. Normal saline emerged as a safe, cost-effective option with studies showing comparable efficacy to active medications in some trials; one emergency department study of 48 patients found saline TPI as effective as conventional active drug mixtures with fewer side effects.

Local anesthetics, particularly lidocaine, are the most commonly used agents, though evidence suggests they may not be superior to saline or other alternatives in all studies. Botulinum toxin type A showed mixed results: Göbel et al's 2006 multicenter trial of 145 patients demonstrated statistically significant pain relief, yet Ferrante et al's 2005 study found no significant difference versus placebo, highlighting the substantial placebo effect in injection studies. Platelet-rich plasma showed potential in small studies, with one report of 78% complete symptom relief in plantar MPS at 1 year, though the authors noted this study lacked randomization and control groups. Platelet-poor plasma, previously considered a waste product, demonstrated similar biological responses to PRP in some musculoskeletal applications, with one trial showing both PRP and PPP produced significant improvement in chronic plantar fasciitis at 6-month follow-up.

Corticosteroids showed inconsistent results: Garvey et al's study of 63 patients found no significant difference versus placebo at 2 weeks, while Sonne et al's study of 30 patients found significantly higher pain improvement in the corticosteroid group after 2 weeks. The authors also noted that ultrasound guidance improves injection accuracy and reduces needle misplacement.

For clinicians, this review suggests that trigger point injection remains a valuable first-line invasive treatment for myofascial pain syndrome, with multiple viable pharmacological options. The choice of injectate may be less critical than proper technique and accurate localization of trigger points. Normal saline offers an attractive option for cost-conscious settings or patients concerned about medication side effects. Glucose prolotherapy shows particular promise for longer-term relief, though optimal concentrations need further study.

The mixed evidence for botulinum toxin and corticosteroids suggests these should be considered second-line or adjunctive options rather than primary treatments. Ultrasound guidance is increasingly supported as the preferred delivery method to enhance precision and safety. For patients, the review indicates that TPI is generally safe, affordable, and can provide meaningful short-term pain relief, though long-term efficacy remains uncertain and may require repeated treatments or combination with exercise and other modalities. The authors emphasize that more high-quality randomized controlled trials with larger sample sizes, standardized protocols, and longer follow-up periods are urgently needed to establish definitive treatment guidelines.

Future research should also focus on developing standardized preparation methods for blood-derived products like PRP and PPP, and on minimizing placebo effects in injection studies to clarify true therapeutic benefits.