Myofascial pain is a chronic pain disorder characterized by the presence of painful localized regions of stiff muscle and/or myofascial trigger points. Intramuscular myofascial trigger point injections are considered first-line treatments for myofascial pain. Common injectates include local anesthetics and botulinum toxin-A (BTX-A). The objective of this systematic review was to compare the effectiveness of local anesthetics and BTX-A on pain intensity in patients with myofascial pain.
A comprehensive systematic search of 3 databases, EMBASE, CENTRAL, and Medline was conducted. The search was comprised of words to describe “myofascial pain” and “injections.” We performed a meta-analysis comparing local anesthetic and BTX-A injections across these follow-up week periods: 0 (immediately following the injection), 1 to 2, 3 to 4, 5 to 6, 7 to 8, 9 to 10, 11 to 12, 16, 18, 24 weeks with local anesthetics and BTX-A as subgroups. We also performed subgroup analyses comparing the effectiveness of local anesthetic injections and BTX-A injections at various muscle locations and comparing the effectives of single versus multiple injection sessions.
In total, 33 studies were included. A qualitative analysis suggested that local anesthetics and BTX-A were inconsistently effective at mitigating pain across all follow-up periods. The meta-analyses revealed that local anesthetic injections were more effective than BTX-A at mitigating pain intensity. Multiple injection sessions of local anesthetics were more beneficial than a single session.
Additional studies are needed to determine sources of heterogeneity mediating the observed differences in effectiveness of local anesthetic and BTX-A injections among the studies. Additional replicative studies are also needed to delineate the relative efficacy and effectiveness of local anesthetic and BTX-A injection. The quantitative results of this study suggest that patients overall experience more pain relief with local anesthetic injections.
Departments of *Psychology
§Kinesiology, McMaster University, Hamilton
†Toronto Rehabilitation Institute, University Health Network
¶Department of Medicine, Division of Physical Medicine and Rehabilitation, University of Toronto, Toronto
‡Department of Science, University of Western Ontario, London, ON, Canada
∥Department of Medicine, Royal College of Physicians and Surgeons, Ireland
The authors declare no conflict of interest.
Reprints: Dinesh A. Kumbhare, MD, PhD, FRCPC, FAAPMR, Department of Medicine, Division of Physical Medicine and Rehabilitation, University of Toronto, Toronto Rehabilitation Institute, 550 University Avenue, Toronto, ON, Canada M5G 2A2 (e-mail: firstname.lastname@example.org).
Received August 29, 2018
Received in revised form November 30, 2018
Accepted December 6, 2018