Excitatory noninvasive brain stimulation (NIBS) of the primary motor cortex (M1) may reduce headache intensity and the frequency of headache attacks in patients with migraine, according to a study published in Headache.
NIBS techniques are emerging as promising clinical interventions for treating migraine. NIBS techniques such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are used to electrically stimulate the brain and modify brain activity to mitigate pain.
The present study is a systemic review and meta-analysis of results from different scientific articles published between January 2000 and September 2018 pertaining to randomized controlled trials studying the efficacy of rTMS and tDCS in patients with migraine. A total of 9 randomized controlled trials were selected, which had a total of 276 participants. Five of the selected articles used rTMS, and 4 of the studies used tDCS. Hedges’ g was calculated to estimate effect size due to the potential baseline differences across the study groups in the meta-analysis. The I2 value was used to examine the statistical heterogeneity, studies with an I2 of 25% to 50% were considered to have low heterogeneity and I2 values of 50% to 75% were considered to have high heterogeneity.
The meta-analysis of excitatory M1 stimulation showed significant effects on reducing headache intensity in patients with migraine (Hedges’ g, -0.94; 95% CI, -1.28 to -0.59; P <.001; I2=18.39%) with large effect size. Regarding the reduction in the frequency of headache attacks, results showed a significant effect with a large effect size (Hedges’ g, -0.88; 95% CI, -1.38 to -0.38; P =.001; I2=57.15%).
Similarly, results from the meta-analysis also showed that excitatory dorsolateral prefrontal cortex stimulation had a significant effect on headache intensity in patients with migraine (Hedges’ g, -1.14; 95% CI, -2.21 to -0.07; P =.04; I2=61.86%) with a large effect size. However, the authors found that the reduction in the frequency of headache attacks was not significant.
The authors note some study limitations. Because the study included a limited number of articles, the estimation of effect size may not have been appropriately powered. The relatively larger sample sizes in 2 of the 9 studies contributed to a large share of the patients, which may have cast an undue influence on the estimated effect sizes. Furthermore, the authors were unable to study the potential differences in the efficacy of rTMS and tDCS due to the fewer studies that were used in the analysis. Further research is needed to validate the findings of the current study.
The authors concluded that excitatory NIBS of the M1 may decrease the intensity and frequency of headache attacks in patients with migraine. “Our findings suggest that therapeutic NIBS for migraine should be focused on excitatory stimulation on the M1,” they added.
Feng Y, Zhang B, Zhang J, Yin Y. Effects of non‐invasive brain stimulation on headache intensity and frequency of headache attacks in patients with migraine: a systematic review and meta‐analysis [published online September 18, 2019]. Headache. doi:10.1111/head.13645