Botulinum toxin for chronic pain: What's on the horizon?
Botulinum toxin has proven safe and effective when used correctly. This review examines the evidence that could support its expanded use.
PRACTICE RECOMMENDATIONS
› Consider botulinum toxin (BoNT) for patients with headache, spasticity, or cervical dystonia, as the FDA has approved BoNT for pain relief in these conditions. A
Strength of recommendation (SOR)
A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series
Plantar fasciitis
BoNT has been used for treatment of plantar fasciitis. Small randomized controlled studies have compared BoNT to both placebo and corticosteroids, showing that BoNT has better long-term outcomes at 3, 6, and 12 months.28,29 BoNT is currently being used when standard treatments have failed; however, larger randomized controlled studies are still needed prior to BoNT being accepted as standard treatment.29
Lateral epicondylitis
A systematic review and meta-analysis done in 2017 showed that BoNT is superior to placebo at 16 weeks. No significant difference was noted between BoNT and corticosteroids at 8 weeks, although corticosteroids did demonstrate better improvement at the short-term interval of 2 to 4 weeks.30 As expected, BoNT was associated with grip-strength weakness compared to placebo and corticosteroids at 12 weeks. Subsequent small randomized controlled studies have continued to show benefit with BoNT, but all studies noted grip weakness (which resolved) and duration of effect was dose dependent.30,31
Temporomandibular joint pain
BoNT has been studied in the treatment of temporomandibular joint (TMJ) pain and dislocations since 1998, and was shown to improve quality of life.32 BoNT has been injected into the musculature surrounding the TMJ, as well as into the joint, and has proven to be effective in these areas.33 There are limited treatment options for TMJ pain and dislocations, and although research is still ongoing, BoNT is considered a potential treatment option.32,33
Myofascial, neck, and back chronic pain
Chronic back pain is common and can be due to multiple conditions. BoNT has been studied for treatment focusing on myofascial pain in the neck and back region. Case series have shown improvement with targeted BoNT injections.34 However, in randomized controlled double-blind studies comparing BoNT to placebo, local anesthetics, and steroids, there were no significant differences in pain scores.35,36 The majority of studies have been landmark based or used the site of maximal tenderness as guidance for injections, but there is some evidence that targeted injections focusing on specific muscle groups may improve benefit.5 This usually requires the use of imaging for guidance.
Chronic pelvic pain
Chronic pelvic pain is common and has been reported to affect 1 in 7 women.37 It is often difficult to diagnose the exact source of the pain, and it can be very difficult to treat. In a 2020 systematic review (including 12 observational studies and 5 randomized controlled trials) of BoNT for treatment of chronic pelvic pain, the quality of evidence varied widely.38 Observational studies showed good benefit, but only 1 randomized trial showed statistical difference with the use of BoNT for pelvic pain. No serious adverse events were reported in any of the studies.38 Chronic pelvic pain can be caused by a number of different conditions, and more high-quality research for BoNT is needed, focusing on specific causes.5,38
Continue to: Complex regional pain
