Table 2.
Summary of tDCS and epilepsy clinical trials.
| Author (year) | Title | Type of article | Experiment | Total sessions | Interval between sessions | N | Montage | Contact area of electrodes | Sham group | Results/insights |
|---|---|---|---|---|---|---|---|---|---|---|
| Fregni et al., 2006 | A controlled clinical trial of cathodal DC polarization in patients with refractory epilepsy | A randomized, sham-controlled clinical trial | Single session of 1 mA c-tDCS for 20 min | 1 session – 20 min | 19 subjects (11 male and 8 female) | Cathodal electrode has been placed over the epileptogenic focus and the anode electrode over a silent area (without epileptogenic activity) | 35 cm2 | Yes (10 active and 9 sham) | c-tDCS reduced EDs (64.3%) and SZ frequency (44%) when compared with sham group (5.8%) and (11.1%) respectively. | |
| Yook et al., 2011 | Suppression of SZs by c-tDCS in an epileptic patient-a case report | Case report | 5 days a week, during 2 weeks. Repeating procedure after 2 month, 20 min (2 mA for 20 min) | 10 sessions-−200 min | 24 h | 1 subject (female) | Cathode electrode applied on midpoint between P4 and T4 area and anode electrode on left supraorbital area. | 25 cm2 | During the first 2 months after treatment; the patient had only six SZs, with an evident clinical improvement, after the second intervention the patient had just one SZ attack over 2 months. | |
| San-Juan et al., 2011 | tDCS in adolescent and adult Rasmussen's encephalitis | Case report | 60 min in 4 sessions (on days 0, 7, 30, and 60) 1 mA for patient (1) and 2 mA for patient (2) | 4 sessions-−240 min | 7, 23 and 30 days respectively | 2 subjects (male) | (1) (C3 [–/cathode]/contralateral supraorbital area [+/anode]) (2) (F2 [–/cathode]/F8 [+/anode]) | Subdermal needle 12 mm in length and 0.4 mm in diameter | One patient was SZ free and another patient showed 50% SZ frequency reduction within 6 month of follow-up. | |
| Faria et al., 2012 | Feasibility of focal transcranial DC polarization with simultaneous EEG recording: preliminary assessment in healthy subjects and human epilepsy | Cross-over controlled trial with 15 healthy subjects and preliminary effects of its use, testing repeated tDCS sessions, in two patients with drug-refractory Continuous Spike-Wave Discharges During Slow Sleep (CSWS) | Once weekly, to 3 afternoon sessions of 30 min each. Current was ramped in steps of 0.1 mA, with a duration of 10 s each, until the target current of 1 mA. | 3 sessions-−90 min | 7 days | 2 subjects (male) | Based in 10–10 International system positions in a cap (mostly C5-C6) | 35 cm2 | A large reduction after c-tDCS was found in IEDs in C5 (mean 32.1%) during and after tDCS (10 min). | |
| Auvichayapat et al., 2013 | tDCS for treatment of refractory childhood focal epilepsy | Controlled study | Single session of 1 mA c-tDCS for 20 min | 1 session-−20 min | 36 subjects (26 male and 10 female) | Cathodal electrode was placed over the epileptogenic focus, centered on the electrode with the international 10-20 EEG electrode placement system location where spikes of sharp waves were greatest in amplitude, and the anodal electrode was placed over the contralateral shoulder area. | 35 cm2 | Yes (27 active and 9 sham) | c-tDCS can suppress EDs frequency in 57.6% for 48 h, but the effect of a single session on EEG abnormalities was not sustained for 4 weeks. A statistical reduction in the frequency of SZs was found (4.8%) in the post-hoc analysis. | |
| Assenza et al., 2014 | Efficacy of c-tDCS in drug-resistant epilepsy: a proof of principle | Single blind and sham-controlled study | Two sessions, (1 sham and 1 real on the 8th and 22th days) 1 mA intensity applied for 9 min | 1 real session-−9 min | 2 subjects (male) | Cathodal electrode has been placed over the epileptogenic focus and the anode electrode over the contralateral homologous region | 12.25 cm2 | Patients showed a consistent reduction of the SZ frequency: about 70% for Patient 1 and about 50% for Patient 2. | ||
| Tekturk et al., 2016b | The effect of transcranial direct current stimulation on SZ frequency of patients with mesial temporal lobe epilepsy with hippocampal sclerosis | A randomized cross-over study | 2 mA for 30 min on 3 consecutive days | 3 real sessions-−90 min | 24 h | 12 subjects (6 male/6 female) | Active electrode placed over the pathologically affected HS side (temporal region, either T3 or T4 electrode place), which was determined by both concordant cranial MRI and ictal or interictal EEG findings, depending on the availability of the seizure records, and reference electrode over the contralateral supraorbital region | 35 cm2 | Ten patients showed a more than 50% decrease in their SZ frequency after c-tDCS. Six patients were SZ-free in the post c-tDCS period of 1 month. | |
| Auvichayapat et al., 2016 | Transcranial Direct Current Stimulation for Treatment of Childhood Pharmacoresistant Lennox-Gastaut Syndrome: a Pilot Study | A randomized, double-blind controlled trial | Five consecutive days of 2 mA c-tDCS for 20 min | 5 sessions-−100 min | 24 h | 22 subjects (14 male and 8 female) | The stimulation site over the left M1, located based on the international electroencephalography (EEG) 10/20 electrode placement system. The reference electrode was placed over the right shoulder area. | 35 cm2 | Yes (15 active and 7 sham) | Participants assigned to the active tDCS condition reported significantly more pre- to post-treatment reductions in SZ frequency and epileptic discharges that were sustained for 3 weeks after treatment. |
| Tekturk et al., 2016a | Transcranial direct current stimulation improves SZ control in patients with Rasmussen's encephalitis | Descriptive study of a small case series | First cathodal, then anodal (2 mA for 30 min on 3 consecutive days for non-sham stimulations), and finally sham stimulation with 2-month intervals | 3 sessions – 90 min | 24 h | 5 subjects (2 male/3 female) | Active electrodes placed over the mostly affected area and reference electrodes over the contralateral mastoid region | 35 cm2 | After cathodal stimulation, all but one patient had a greater than 50% decrease in SZs frequency. Two patients who received modulated c-tDCS had better results. The longest positive effect lasted for 1 month. | |
| Zoghi et al., 2016 | The effects of cathodal transcranial direct current stimulation in a patient with drug-resistant temporal lobe epilepsy (case study) | Case report | 2 sessions of 1 mA c-tDCS (9–20–9 protocol) during a total of 18 min, with 20 min rest after the first 9 min | 2 sessions-−18 min | 20 min | 1 subject (female) | The active electrode (cathode, 3 × 4 cm) was placed over the right temporal lobe, and the return electrode (anode, 5 × 7 cm) was placed over the left supraorbital area | Cathode, 12 cm2 and anode, 35 cm2 | SZs reduced from 6-10 per day to 0–3 SZs per day. SZ frequency remained as low as 0–3 per day for 4 months, and then started to increase again. | |
| Assenza et al., 2017 | Cathodal transcranial direct current stimulation reduces seizure frequency in adults with drug-resistant temporal lobe epilepsy: a sham controlled study | A double-blind, randomized, sham-controlled, crossover, monocentric study | 1 real session of 1 mA c-tDCS during 20 min | 1 session-−20 min | 30 days | 10 subjects (male) | The cathode was placed over the epileptic focus, localized by means of EEG interictal and ictal activity, and the anode over the contralateral homologous region | 35 cm2 | c-tDCS reduced the percent weekly seizure frequency more than sham stimulation, without any change in interictal epileptiform activity | |
| San-Juan et al., 2017 | tDCS in Mesial Temporal Lobe Epilepsy and Hippocampal Sclerosis | A randomized, double-blinded, placebo-controlled, 3-arm parallel group (placebo, 30 min/2 mA daily sessions for 3 days, and 30 min/2 mA daily sessions for 5 days) clinical trial | 2 mA for 30 min on 3 or 5 consecutive days of treatment | 3 sessions-−90 min or 5 sessions-−150 min | 24 h | 28 subjects (16 male and 12 female) | The cathode was positioned over the most active IED area (defined as the zone [electrodes] with the highest discharge amplitude and/or frequency, located with the 10/20 system) as observed on the scalp EEG immediately before applying the tDCS. The anode electrode was placed over a silent supraorbital area (i.e., without epileptogenic activity) contralateral to the stimulated MTLE-HS side | 35 cm2 | Yes (20 active and 8 sham) | c-tDCS of 3 and 5 sessions decreased the frequency of SZs and IEDs (baseline vs. immediately post-tDCS). |
c-tDCS: Cathodal transcranial direct-current stimulation; EDs: Epileptiform discharges; EEG: Electroencephalogram; IEDs: Interictal epileptiform discharges; SZs: Seizures; tDCS: Transcranial direct-current stimulation.