Efficacy of Botulinum Toxin in Tension-Type Headaches: A Systematic Review of the Literature.

[BACKGROUND] Botulinum toxin is approved to treat chronic migraine and has been shown to confer significant benefit in refractory cases. Due to its effect on pain by sensory modulation, there may also be efficacy in its use in chronic tension-type headache (CTTH).

[METHODS] A systematic review of the literature was performed using our predefined inclusion and exclusion criteria. We targeted prospective trials, randomized or nonrandomized, studying botulinum toxin in tension-type headaches (TTHs) in adults.

[RESULTS] Twenty-two studies were included, including 9 nonrandomized, uncontrolled studies, 8 randomized, placebo-controlled and double-blinded trials (RCTs), 3 RCTs with a crossover, open-label period, 1 comparative, randomized, single-blinded evaluation, and 1 retrospective study with prospective evaluation of headache response to cosmetic botulinum toxin. Studies included 11 to 300 subjects, with duration typically less than 6 months and with only 1 treatment period. Results were mixed, likely due to variable study design, including toxin dosing, injection paradigms, duration/frequency of treatment, and outcome measures. There was moderate-quality evidence that botulinum toxin improved VAS scoring, and some studies demonstrated efficacy based on improved frequency/severity.

[CONCLUSION] This systematic review demonstrates variable study designs contributing to the low quality of evidence available regarding botulinum toxin in TTH, but some data suggest efficacy. There does not appear to be irrefutable evidence of a lack of efficacy of botulinum toxin in TTH. Using the paradigm for botulinum toxin in chronic migraine may prove fruitful in treating CTTH. Further studies are warranted to evaluate the utility of botulinum toxin in this common debilitating condition.