Efficacy of transcranial direct current stimulation on seizure control in patients with refractory epilepsy: a systematic review and meta-analysis of randomized controlled trials

Abstract

Drug-resistant epilepsy is a challenging condition that affects around 30% of all patients with epilepsy. Evidence regarding treatment options is limited, especially for surgery and invasive techniques. However, non-invasive techniques constitute a promising alternative for these patients. This meta-analysis aims to evaluate the effectiveness of transcranial direct current stimulation on seizure frequency management in patients with drug-resistant epilepsy. We searched the literature in PubMed, Scopus, and Web of Science up to December 2023. We included randomized controlled trials that compared transcranial direct current stimulation with sham stimulation. Our main outcomes of interest were a percentage reduction in seizure frequency and epileptiform discharge frequency. A total of 10 studies with 269 patients were included. Monthly seizure frequency was significantly reduced by an average of -45.39%and -39.34% at week 4 and week 8, respectively. There was a significant reduction in IED in favor of tDCS at week 2 (SMD = -0.87, 95% CI = [- 1.49, - 0.25], P = 0.006), 4 weeks (SMD = -1.17, 95% CI = [- 1.67, - 0.66], P < 0.00001, Moderate quality of evidence) and 8 weeks (SMD = -1.11, 95% CI = [- 1.69, - 0.53], P = 0.0002) of follow-up. There were no serious adverse events associated with the stimulation. Transcranial direct current stimulation was associated with a reduction in both seizure frequency and epileptiform discharges with minimal side effects. Further studies with larger sample sizes and consensus protocol guidelines are needed to verify its long-term safety and effectiveness.

Keywords: Drug-resistant epilepsy; Non-invasive neurostimulation; Seizure frequency; Transcranial direct current stimulation; tDCS.

Fig. 1

PRISMA flowchart

Fig. 2

The risk of bias summary and graph according to the cochrane risk of bias assessment tool 2

Fig. 3

Forest plot of monthly seizure frequency percentage reduction at 4 and 8 weeks

Fig. 4

Forest plot of weekly seizure frequency percentage reduction at 4 weeks

Fig. 5

Forest plot of seizure frequency sub-grouped based on the intensity of stimulation

Fig. 6

Forest plot of seizure frequency sub-grouped based on the duration of stimulation

Fig. 7

Forest plot of epileptiform discharge at different time points

Fig. 8

Publication bias assessment (DOI graph) of the seizure frequency outcome at 4 weeks

Fig. 9

Publication bias assessment (DOI graph) of the epileptiform discharge outcome at 4 weeks