Previous studies have suggested that migraine is linked with higher visual neuronal excitability, which can be inhibited through noninvasive brain stimulation.
In a small study, researchers found that transcranial alternating current stimulation (tACS) given at home could reduce or stop pain from acute migraine, but the current process is currently too complex and needs refinement.
This form of noninvasive electrical brain stimulation is normally provided in a medical setting, but the researchers theorized that at-home administration could lower costs and increase patient convenience. The aim of this double-blind, placebo-controlled parallel group study was to determine a protocol and examine efficacy for self-administered tACS for migraine.
The authors said that to their knowledge, tACS has not been tried previously in patients with migraine.
The study called for having patients target the visual cortex at the onset of migraine attack through the use of either active (0.4 mA, 140 Hz) or sham stimulation for 15 minutes. The primary endpoint was the number of terminated attacks 2 hours post-stimulation; they were told to treat a maximum of 5 migraine attacks over the course of 6 weeks. If the attacks did not resolve at 2 hours, patients could take their usual medication.
Patients were trained in how to apply the electrodes, which delivered low-intensity, high-frequency stimulation; the researchers wrote that previous studies have suggested that migraine is linked with higher visual neuronal excitability, which can be inhibited through noninvasive brain stimulation. The idea is that the transcranial oscillations can reset the brain, “forcing the network to restore adequate synchronization and excitation/inhibition balance.”
While research is not entirely clear on how the process works, it is believed that tACS over the visual cortex, besides reducing local hyperresponsiveness, could also “modify the activity of the brainstem through nociceptive pathways. It is suggested that there is a functional connection between the visual cortex and brainstem second-order nociceptors in the spinal trigeminal nucleus.”
Patients were recruited from outpatient clinics in Germany. Out of 40 patients, just 25 finished the study, 16 in the active and 9 in the sham group. A total of 102 migraine attacks were treated.
The percentage of terminated migraine attacks not requiring acute pain relief medication was significantly higher in the active (21.5%) than in the sham group (0%). In addition, the perceived pain in the active group was significantly less for 2 to 4 hours post-stimulation.
The authors said the good results and high drop-out rate suggests that this method is impeded by its complexity and time-consuming setup, as the electrodes take longer to position than taking medicine. Future studies could involve family members or caregivers, but the researchers also pointed out that use of the treatment would be limited if an attack started and the stimulator was not immediately available.
Antal A, Bischoff R, Stephani C, et al. Low intensity, transcranial, alternating current stimulation reduces migraine attack burden in a home application set-up: a double-blinded, randomized feasibility study. Brain Sci. 2020 Nov; 10(11) 888. doi: 10.3390/brainsci10110888