Efficacy and mechanisms of transcranial electrical stimulation in headache disorders

Headache is the one of the most common problems contributing to suffering worldwide and sometimes it causes disability. Some patients are unable to use the drugs for various reasons and some are resistant to the pharmacological treatment. Therefore, additional effective non-pharmacological treatments are sought. Transcranial electrical stimulation techniques have been developed as potential therapeutic options. Among these techniques, transcranial direct current stimulation (tDCS) is the only technique studied for the treatment of headache. TDCS is a neurophysiological technique with multifarious advantages encompassing its low-cost, high tolerability and acceptability, comfortable application and the opportunity to use concomitantly with other treatments. Steadily increasing interest in tDCS stems from the multidisciplinary advances in neuroscientific backgrounds of neuropsychiatric diseases. Even though exact mechanisms behind benefits of tDCS have not yet been clearly disclosed, changes in multitudinous chemical and physiological parameters have been demonstrated. The purpose of this review is to summarize what is currently known regarding the effects of tDCS on the treatment of headache focusing mostly on migraine. Herein, tDCS procedures that may be helpful for primary headache treatment were described. TDCS has shown promise for effectively treating primary headaches with no severe adverse effects. The findings indicate that the analgesic effects of tDCS can last for a long period and can occur after the time of stimulation. Additional research is required for the determination of optimized stimulation protocols in each specific headache disorder.