Botulinum neurotoxin-A for treatment of refractory neck pain: a randomized, double-blind study.

OBJECTIVE: To investigate the efficacy and tolerability of Botulinum neurotoxin-A (BoNT-A) in the patients with refractory neck pain.

BACKGROUND: An analgesic effect is suggested for BoNT-A by a number of animal studies. Two blinded studies suggested efficacy of BoNT-A in a chronic neck pain.

METHODS: Forty-seven subjects were enrolled in a prospective, double-blind, placebo-controlled study. A total of 150 to 300 units of BoNT-A were injected into the neck and shoulder muscles based on pain localization. Subjects completed the visual analog scale (VAS), Pain Frequency Questionnaire and the Modified Oswestry Pain Questionnaire (MOPQ) at baseline, 3 and 8 weeks after the treatment. The primary outcomes consisted of: 1) > or =50% improvement on the VAS; and 2) > or =30% reduction in pain day frequency. The secondary outcome was an improvement of ADL in MOPQ. Excellent responders (ERs) were those who met all three outcomes.

RESULTS: At 2 months, a significant reduction in the mean VAS (pain intensity) was noted in the BoNT-A group compared with the placebo (P = 0.0018, CI 95% from 2.51 to 7.89). At 2 months, there were six ERs in the BoNT-A group and one ER in the placebo group (P = 0.0152).

CONCLUSION: Administration of BoNT-A into the neck and shoulder muscles for treatment of chronic refractory neck pain met one of the two primary outcomes: reduction in pain intensity. More ERs were noted in the Botox group.