Table 2.

Transcranial direct current stimulation (tDCS) studies as prophylactic treatment of migraine or cluster headache

Authors	Participants	Study	Treatment	Results
Dasilva et al. [39]	CM = 13	Randomised sham-controlled trial	Anode over M1	↓ in pain intensity after 4 months with tDCS than sham
Andrade et al. [42]	CM = 13	Pilot, double-blind, placebo-controlled, randomised trial	Anode over M1 or DLPFC	Group under DLPFC stimulation exhibited a better clinical performance compared with groups under M1 and sham stimulations. On intragroup comparison, groups DLPFC and M1 exhibited a greater reduction in headache impact and pain intensity and a higher quality of life after real treatment. No significant change was found in the group under sham stimulation
Magis et al. [48••]	CCH = 31	Pilot trial	Anode over Fz	↓ of attacks frequency, duration, and intensity
Mansour et al. [44]	MOH = 18	Pilot, double blind, sham-controlled, and cross-over design	Cathode over V1 of the headache side, anode over the supraorbital area on the non-headache side For prefrontal tDCS, the anode and cathode were respectively positioned over left and right DLPFC	Both locations: ↓of the total number of migraine days, severe migraine days in the week following the intervention. Occipital tDCS: ↓in the consumption of tablets, clinical effects outlasting the follow-up period of 14 days
Grazzi et al. [45]	MOH or CM = 135	Multicentre, double-blind, placebo-controlled trial with ensuing 1-year open-label study	Anodal, cathodal, or sham tDCS over the right M1	Lack of efficacy of tDCS on the reduction of migraine days and analgesics/months variables
Dalla Volta et al. [128]	CM = 45	Pilot, sham-controlled	Cathodal stimulation unilaterally on the frontal cortex over the cold patch as identified by thermographic examination	↓ in migraine days, headache days, attacks duration, pain intensity, tablets intake
Rahimi et al. [43]	M & CM = 45	Randomised, single-blind, and sham-controlled design	Cathode over the right M1 or S1	tDCS over M1 and S1 ↓ migraine pain frequency, duration, and intensity

CCH chronic cluster headache, CM chronic migraine, DLPFC dorsolateral prefrontal cortex, M1 primary motor cortex, M migraineur patients, MA migraine with aura, MO migraine without aura, MOH medication overuse headache, S1 primary somatosensory cortex, tDCS transcranial direct current stimulation, V1 primary visual cortex