The efficacy of onabotulinumtoxinA injections in chronic migraine (CM) is rapid, robust, and sustained, according to a recent French study published in The Journal of Headache and Pain.1 The study reported a high degree of response, measured by a reduction in headache days per month, reduced muscle pain and tenderness, and a significant drop in the use of rescue medications, as well as a high degree of patient satisfaction with the therapy. Moreover, the study design, which entailed a protocol for individualized mapping of injection sites, contributes strong evidence supporting a role for myofascial trigger points (TRPs) in the chronicity of migraine pain.
A team of investigators from the pain center and department of Neurosurgery at the Centre Hospitalier Universitaire de Limoges in France conducted an observational open-label study in a cohort of 41 patients enrolled from 2008 to 2015 with CM (43 female/14 male, age 17-85; mean age, 44.5) who had no response to at least 2 prophylactic agents. The study was unusual in that it first included what the investigators termed an “adaptation” period, designed to identify the optimal injection sites for each patient using a “follow-the-pain” approach guided by Travell & Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual.2 This phase included up to 3 sessions in which the patients were questioned about features of their attacks while the examiner searched for corresponding TRPs in the corrugator, temporalis, and trapezius muscles to map the injection sites.
This was followed by an observation period that tracked CM patterns 8 weeks prior to the first effective treatment injection and 8 weeks after the last injection. Onset of efficacy was rapid, occurring within days of the first injection, with 41 of 63 treated patients (72%) reaching the primary outcome of ≥50% reduction in headache days over 2 or more consecutive injection cycles. Of these, nearly 93% of participants surpassed the desired outcome; 29 patients (70.7%) reported a reduction of headache days of ≥70%, and 9 patients (22%) were virtually headache-free (reporting ≤1 headache days per month), with a duration that lasted from 3 to 4 months. Triptan use was also reduced by a mean of 81% in 28 patients taking these medications prior to enrollment.
In addition to establishing efficacy, with good safety and tolerability, the study also allowed for a number of observations about the nature of CM. The most prominent muscle contributing to CM appeared to be the trapezius, as 38 of 41 participants (92%) required injections to that site. Responders were more likely than nonresponders to have a pattern of painful cervical muscle tension before, during, and between attacks. At the same time, there were no differences in baseline characteristics of age, sex, use of triptans, or the number of headache days per month between responders and nonresponders.
If these results are confirmed by further investigations, the researchers wrote, “it could be suggested that myofascial pain and TrPs may contribute to headache pain in CM patients and constitute an important factor of migraine chronicization.”
The study had 2 main limitations, including a small sample size and the lack of a placebo arm, although the high placebo effect in migraine is difficult to overcome, the researchers noted.
- Ranoux D, Martiné G, Espagne-Dubreuilh G, Amilhaud-Bordier M, Caire F, Magy L. OnabotulinumtoxinA injections in chronic migraine, targeted to sites of pericranial myofascial pain: an observational, open label, real-life cohort study. J Headache Pain 2017;18:75.
- Simons DG, Travell JG, Simons LS. Myofascial Pain and Dysfunction: The Trigger Point Manual, vol 1.. Philadelphia, PA: Lippincott Williams & Wilkins, 1999.