Botulinum Toxin Injections for Low-Back Pain and Sciatica
Intramuscular Botulinum Neurotoxin functions by inhibiting nerve impulses, resulting in muscle relaxation or paralysis. The injections typically take effect within a few days and their duration of action lasts between three to six months. Repeated injections may be required for sustained benefits.
Commercially, botulinum toxin is provided in small amounts and is offered in two different serotypes: A and B. BoNT-A is available as Botox®, Dysport®, Lantox®, and Xeomin®, while BoNT-B is sold as Myobloc® in the U.S. and Neurobloc® in Europe.
Botox® is FDA-approved for cervical dystonia, axillary hyperhidrosis, blepharospasm, and glabellar lines, while Myobloc® is approved for cervical dystonia. The American Academy of Neurology recommends botulinum toxin for spasticity, certain movement disorders, and hyperhidrosis.
It may also have potential in treating pain disorders. Common side effects include injection site pain, irritation, muscle weakness, and rash. Serious reactions are rare but can include anaphylaxis and paralysis.
Concerns have been raised about the spread of botulinum neurotoxin beyond the treatment site, prompting black box labeling by Health Canada and the FDA.
Muscle contractions, contractures, and spasms contribute to pain from local ischemia. BoNT injections relax muscles and have been shown to reduce inflammatory markers.
The specific population that benefits most from BoNT injections for lower back pain is unclear, but they may be helpful for individuals with muscular pain or spasms.
Three trials involving a total of 123 participants were selected (Foster 2001; Fishman 2002; Liu 2008). These trials had variations in participant characteristics and the specific diagnoses being investigated.
While all three trials used Botulinum toxin serotype A (BoNT-A), differences were observed in the preparation, dosage, number of injections, targeted muscles, injectant volume, and needle type.
\Detailed information on the study by Herskowitz 2004 could not be fully assessed due to limited available data from an unpublished abstract.
In one study reported by literature, participants received BoNT injections along with standard physical therapy for twelve weeks, while the control group received only physical therapy.
Pain intensity was the primary outcome measure in two studies, and improvement levels based on pain and function were assessed in another study. The timing of outcome measurements varied across the studies.
Adverse effects were reported in some studies, while cost and work-related outcomes were not addressed.
Limited evidence exists on the effectiveness of BoNT injections for treating lower back pain (LBP). Only three trials met the inclusion criteria for this review, indicating a lack of available research on the topic.
A study with a low risk of bias demonstrated that BoNT injections were more effective than saline in relieving pain and improving function. Another study found that BoNT injections were superior to lidocaine or placebo in reducing pain associated with piriformis syndrome.
Furthermore, an additional study found that BoNT injections yielded more favorable outcomes when compared to traditional acupuncture.
Due to variations in patient populations, BoNT injection characteristics, and outcome measures, meta-analysis was not possible. Cost-benefit analysis and assessment of clinical relevance were not addressed in the studies.
Significant pain relief was observed in Foster 2001 and Fishman 2002, but the magnitude of improvement could not be determined without absolute changes in pain scores.