Which is the best transcranial direct current stimulation protocol for migraine prevention? A systematic review and critical appraisal of randomized controlled trials

Abstract

Background Transcranial direct current stimulation (tDCS) could counteract the pathophysiological triggers of migraine attacks by modulating cortical excitability. Several pilot randomized controlled trials (RCTs) assessed the efficacy of tDCS for migraine prevention. We reviewed and summarized the state of the art of tDCS protocols for migraine prevention, discussing study results according to the stimulations parameters and patients’ populations. Main body We combined the keywords ‘migraine’, ‘headache’, ‘transcranial direct current stimulation’, and ‘tDCS’ and searched Pubmed, Scopus, and Web of Science, from the beginning of indexing to June 22, 2021. We only included RCTs comparing the efficacy of active tDCS with sham tDCS to decrease migraine frequency, intensity, and/or acute drug utilization. The risk of bias of each RCT was assessed by using the RoB-2 tool (Cochrane Collaboration). Thirteen RCTs (from 2011 to 2021) were included in the review. The included patients ranged from 13 to 135. RCTs included patients with any migraine (n=3), chronic migraine (n=6), episodic migraine (n=3) or menstrual migraine (n=1). Six RCTs used cathodal and five anodal tDCS, while two RCTs compared the efficacy of both cathodal and anodal tDCS with that of sham. In most of the cathodal stimulation trials, the target areas were the occipital regions, with reference on central or supraorbital areas. In anodal RCTs, the anode was usually placed above the motor cortical areas and the cathode on supraorbital areas. All RCTs adopted repeated sessions (from 5 to 28) at variable intervals, while the follow-up length spanned from 1 day up to 12 months. Efficacy results were variable but overall positive. According to the RoB-2 tool, only four of the 13 RCTs had a low risk of bias, while the others presented some concerns. Conclusions Both anodal and cathodal tDCS are promising for migraine prevention. However, there is a need for larger and rigorous RCTs and standardized procedures. Additionally, the potential benefits and targeted neurostimulation protocols should be assessed for specific subgroups of patients.

Analgesic Effects of Repetitive Transcranial Magnetic Stimulation in Patients With Advanced Non-Small-Cell Lung Cancer: A Randomized, Sham-Controlled, Pilot Study

“…DLPFC directly promotes or inhibits pain through coordination with these brain regions or through modulating the activity of pain descending inhibition pathways ( 31 ). Therefore, DLPFC-rTMS was able to reduce pain sensation, as supported by several recent studies, like spinal cord injury ( 12 ), migraine ( 13 ) and fibromyalgia ( 14 ). In this study, we hypothesized that DLPFC-rTMS may also be effective in the treatment of cancer pain and thus conducted this trial.…”

“…Usually, low frequency (< 1Hz) stimulation has an inhibitory effect on the brain, while high frequency (> 5Hz) stimulation excite neurons ( 11 ). It has been reported that rTMS relieves various types of pain, such as neuropathic pain after spinal cord injury, stroke or postoperative of trigeminal nerve ( 12 ), migraine ( 13 ), fibromyalgia ( 14 ) and chronic musculoskeletal pain ( 15 ). Even less clinical study has been done on the application of rTMS in patients with cancer pain.…”

Effectiveness of Transcranial Direct Current Stimulation and Monoclonal Antibodies Acting on the CGRP as a Combined Treatment for Migraine (TACTIC): Protocol for a Randomized, Double-Blind, Sham-Controlled Trial

“…So far, several studies have already evaluated tDCS for migraine prevention proving that it is a promising treatment to prevent migraine ( 36 , 40 – 50 ). Available RCTs included a variable number of patients (from 15 to 135 patients) with highly heterogeneous patient populations, outcomes, time schedules, and tDCS montages ( 34 ). Most of the available RCTs performed either cathodal occipital stimulation with anterior reference ( 40 , 43 , 44 , 46 ) or anodal frontal stimulation with supraorbital reference ( 36 , 41 , 42 , 45 ).…”

“…Results of those RCTs were overall positive in the short term, while being more controversial 12 months after tDCS ( 36 , 48 ). The available RCTs are limited by the underuse of neurophysiological tests, which would improve our understanding of the effect of tDCS and how to improve it ( 34 ).…”

“…The stimulation will be applied via 4 conductive-rubber square electrodes (5 × 5 cm) placed in sponges saturated with high conductivity gel and connected to a battery-operated stimulator system (BrainSTIM, EMS medical). In the active tDCS group, a direct current with maximal intensity of 1.5 mA with be provided for 20 mins (30 s ramp-in/ramp-out); those parameters are within the range of the available randomized controlled trials ( 34 ). In the sham group, the current will be turned off after 10 s (30 s ramp-in/ramp-out) at the beginning and at the end of the 20-min interval, in order to maintain the same tingling sensation that subjects refer during the gradual increase/decrease of the current intensity at the beginning/end of the ‘real' stimulation procedure.…”