Cathodal HD-tDCS and attention: A study on patients with intractable left lateral frontal lobe epilepsy.

OBJECTIVE: Defects in the attentional network in patients with epilepsy are influenced by factors such as the location of epileptic foci. Examining the impact of cathodal high-definition transcranial direct current stimulation (HD-tDCS) on attention components could provide insights into potential attention-related side effects of tDCS. This study aimed to investigate the effect of cathodal HD-tDCS on interictal epileptiform discharges (IEDs), auditory/visual (A/V) attention components, and reaction time (RT) in patients with intractable focal left lateral frontal lobe epilepsy (LFLE). METHODS: To control for variations in individual epilepsy syndrome, 12 adult participants diagnosed with drug-resistant left LFLE with focal cortical IEDs on C3 underwent repeated measurements at pretest, posttest, and follow-up steps. 4 × 1 ring electrodes (cathode on C3 and four anodes on F3, P3, T3, and Cz) delivered 2 mA DC for 20 min per session for 10 consecutive days. The integrated visual and auditory continuous performance test (IVA+) assessed the A/V attention components and RT. One-way repeated-measure ANOVA was used. RESULTS: The findings suggest a significant effect in reducing IEDs. The IVA+ results showed a significant improvement in auditory divided attention and visual selective and focused attention (p < 0.05). In the follow-up, these changes demonstrated lasting efficacy. A/V speed scales increased (p < 0.05), showing a significant decrease in reaction time. CONCLUSIONS: Cathodal HD-tDCS significantly reduced IEDs and improved the components of auditory divided attention, visual focused attention, and visual selective attention, with a reduction in patient reaction time. A significant lasting, side-effect-free positive effect was observed for up to one month after the intervention.

HD-tDCS in refractory lateral frontal lobe epilepsy patients.

PURPOSE: To evaluate the anticonvulsant effect of the novel high definition transcranial direct current stimulation (HD-tDCS) method on patients with refractory lateral frontal lobe epilepsy. The effects of HD-tDCS on working memory were also examined. METHOD: 10 adult patients with intractable lateral frontal lobe epilepsy were studied. A central cathode electrode was placed on the epileptogenic zone according to LTM, and 20-min sessions of 2mA HD-tDCS were applied for 10 consecutive days. The primary endpoint was to make changes in the epileptiform discharges (EDs) during a 1-h EEG. Moreover, the seizure frequency based on seizure diary and neuropsychiatric parameters was evaluated. RESULTS: All patients tolerated HD-tDCS stimulation course without any adverse reaction. The frequency of EDs increased immediately and one month after the stimulation course by an average of 6.4% and 1.2%, respectively. However, these changes in the EDs frequency were not statistically significant (p-value >0.05). The mean seizure frequency changes showed decrement by an average of 17.9% immediately, and increment by an average of 38.1% one month after the HD-tDCS. These changes were not significant statistically (p-value >0.05). One patient experienced exacerbation of seizures during the stimulations hence dropped out of the study. Attention and working memory improved significantly immediately and one month after the HD-tDCS in all patients. CONCLUSION: Changes of EDs and mean seizure frequency caused by HD-tDCS were not statistically significant for the whole group; however, this method could improve the patients' working memory scores.