Immediate and Long-Term Effects of Different Montages of Transcranial Direct Current Stimulation Over Primary Visual...

We evaluated the immediate and long-term therapeutic efficacy of transcranial direct current stimulation (tDCS) using two distinct montages of anodal and cathodal electrical stimulation over the primary visual cortex compared with a sham tDCS in patients with chronic migraines.

In this randomized, double-blind, controlled trial, 72 eligible patients with resistant chronic migraine were randomly assigned to one of three groups, receiving anodal or cathodal (2 mA for 20 min), or sham tDCS (0.5 mA for 30 s), over the pain-dominant side of the primary visual cortex. Clinical features including the number of migraine attacks per month, attack duration, pain intensity, and frequency of painkiller use at baseline, 2 months after starting and ending tDCS therapy were recorded using a personal questionnaire.

Both anodal and cathodal real tDCS protocols resulted in a significant reduction in the number of attacks, pain intensity, attack duration, and frequency of painkiller use during the treatment period compared to baseline. There was no significant difference between the two treatment groups regarding the therapeutic efficacy. However, only anodal tDCS significantly maintained the beneficial therapeutic effects on the number of migraine attacks and painkiller use at the follow-up phase. The sham protocol did not produce any significant clinical utility in this population.

The study supports the analgesic effects of the proposed real tDCS approaches in patients with resistant chronic migraine. Anodal tDCS may offer superior benefits to cathodal tDCS, likely by stabilizing therapeutic outcomes through reorganizing the thalamocortical pathway.