Transcranial Direct Current Stimulationx
Transcranial direct current stimulation (TDCS) uses weak currents, applied via electrodes attached to the scalp, to modify the resting membrane potential of cortical neurons in the stimulated and interconnected regions. Anodal stimulation increases neuronal firing, while cathodal stimulation inhibits neuronal firing. An animal study found that the propagation velocity of cortical spreading depression was significantly increased by anodal TDCS, suggesting that such stimulation may increase the probability of migraine attack in migraine with aura patients. A recent study found that 3–4 weeks after 20 min of treatment for 5 consecutive days, patients with drug-resistant trigeminal neuralgia, poststroke pain syndrome, back pain and fibromyalgia, when given anodal TDCS, had greater improvement in pain than those given sham stimulation. In another study, TDCS was investigated in chronic migraine patients. No difference in response rate was found between the stimulated and sham-stimulated groups (polarity not stated).
In 26 patients with episodic migraine, Antal et al. compared cathodal TDCS with sham stimulation applied three times a week for 6 weeks over the primary visual cortex. Migraine intensity reduced more in the TDCS than sham group; however, migraine days, headache duration and headache intensity fell significantly in both groups over the study period. Side effects were minor and transient.
DaSilva et al. compared TDCS over the primary motor cortex with sham stimulation in 13 chronic migraine patients. Post hoc analysis showed a significant reduction in pain intensity during follow-up (120 days) in the TDCS group only, which was suggested to be owing to the slow modulation of pain matrix structures. Further studies are required to determine whether or not TDCS is effective in migraine.
Future Neurology. 2013;8(4):457-467. © 2013 Future Medicine Ltd.