Botulinum Toxin A Treatment Associated with Improvements in Essential and Isolated Head Tremor According to Results from RCT

Injection of botulinum toxin A into the splenius capitis muscle was associated with reductions in the severity of essential and isolated head tremor, according to results from a randomized clinical trial published in The New England Journal of Medicine. Secondary outcome measures from this study suggest that the beneficial effect of botulinum toxin A wanes by 12 weeks after injection.

The multicenter, randomized, double-blind, placebo-controlled clinical trial (NCT02555982) was conducted across 19 medical centers in France, enrolling 117 participants who were randomly assigned to receive either botulinum toxin A (n = 62) or placebo (n = 55) at weeks 0 and 12. The primary outcome measured was 2-point improvement on the Clinical Global Impression of Change (CGI) scale, measured at week 18. Secondary outcomes were measured at weeks 6, 12, and 24, assessing changes from baseline in the characteristics of tremor.

The primary outcome was met in 31% of the participants who received botulinum toxin A and 9% of the participants who received placebo (95% CI, 1.35 to 8.42; P = .009), demonstrating clinically significant improvement in symptom severity. Analysis of secondary outcome results supported the primary outcome measures at week 6 and 12, but not at week 24, suggesting that the beneficial effects of local injection of botulinum toxin A waned by 12 weeks after the second injection. Adverse events were reported in approximately half of the participants and  included head and neck pain, posterior cervical weakness, and dysphagia.

This study was conducted with funding from the French Ministry of Health.