What is the role of botulinum toxin (BTX) injection in the treatment of neck pain?

Updated: Jun 19, 2018
  • Author: Anthony H Wheeler, MD; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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Padberg et al conducted a randomized controlled trial in 40 patients who experienced chronic pain due to whiplash-associated disorders (WAD). [64] Study participants were randomly assigned to receive BTX-A (maximum 100 U) or placebo (NS) into muscles that were felt to be symptomatic by demonstration of increased tenderness. No significant differences could be determined between groups at 4, 8, and 12 weeks as measured by neck pain intensity using VAS, mean number of neck pain days or pain hours per day, days requiring treatment for symptoms, number of analgesics taken per day, and cervical range of motion. No significant improvement was noted after 4, 8, and 12 weeks. This study did not show any beneficial treatment effect when tender muscles, presumed to be due to WAD, were injected with BTX-A.

Similar findings were noted by Carroll et al in a prospective, double-blind, randomized controlled trial. [65] In this study, 37 patients with symptomatic WAD lasting longer than 2 months were randomized to receive either 250 U BTX-A (Dysport) or NS. Each received 4 trigger-point injections of 0.625 mL. Tenderness to palpation, VAS scores, the Vernon-Mior Index, and cervical range of motion were assessed at baseline, at 4 week,s and at 3 months after treatment. The findings of this study were consistent with most previous studies in showing a tendency towards improvement in all measures in both groups. However, changes in the Vernon-Mior Index, which measures pain and disability, were both statistically and clinically significant in the BTX-A group. Group comparisons did not meet statistical significance. The authors were optimistic in suggesting that BTX-A may have a beneficial role in the treatment of WAD, but larger studies are necessary to determine any such use at present.

Tender points due to WAD, rather than trigger points, were injected by Braker et al in 20 patients diagnosed with cervical MPS, 2-48 weeks after injury. [66] Patients were randomly assigned to receive either 200 U of BTX-A or placebo at 4 tender points, and progress was measured at 3, 6, 9, 12, and 24 weeks following the injection session. Outcome measures included VAS intensity scores, 5-point Verbal Rating Scale (VRS), quality of life assessed by the SF-36 questionnaire, global assessment scores by both physician and patient, tenderness from mechanical pressure, and cervical range of motion. These data are confounding because some patients, who were acute or subacute, were likely to improve based on natural history. The authors' observations of a time-dependent improvement in all the parameters is suspect as a study result.

Consistent with prior cervical studies, improvement was demonstrated in both groups, and although improvement was larger in the BTX-A group, the difference was not statistically significant. Systemic adverse effects were more common in the BTX-A group (40% vs 0%, P=0.07). The authors joined suit in recommending the need for a larger well-designed clinical study.

To investigate the efficacy and tolerability of BTX-A in patients with refractory neck pain, 47 subjects were enrolled in a prospective, double-blind, randomized controlled trial. [67] Participants received a total of 150-300 units of BTX-A injected into the neck and shoulder muscles based on pain localization and the area involved. Subjects completed the VAS (pain intensity), Pain Frequency Questionnaire, and the Modified Oswestry Pain Questionnaire (MOPQ) at baseline and 3 and 8 weeks after the treatment. Primary outcomes consisted of (1) 50% or more improvement on the VAS and (2) 30% or more reduction in pain day frequency. Secondary outcome was improvement of activities of daily living in the MOPQ. Excellent responders (ERs) were those who met all 3 outcomes.

At 2 months, a significant reduction in the mean VAS was noted in the BTX-A group compared with placebo; 6 ERs were found in the BTX-A group compared with 1 ER in the placebo group. Administration of BTX-A into the neck and shoulder muscles for treatment of chronic refractory neck pain met only 1 of the 2 primary outcomes (reduction in pain intensity).

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