The effect of cathodal transcranial direct current stimulation on spike-wave activity in the EEG of patients with drug-resistant focal epilepsy

Introduction: Epilepsy is a chronic neurological disorder that affects more than 70 million people worldwide. Drug-resistant epilepsy refers to a challenging clinical condition in which seizures persist despite the use of antiepileptic drugs. This study aimed to investigate the effects of cathodal transcranial direct current stimulation (tDCS) on spike-wave activity observed in electroencephalography (EEG) in patients with drugresistant focal epilepsy. Method: tDCS was applied to 15 patients at an intensity of 2 mA for 30 minutes per day over five consecutive days. The cathode electrode was placed over the epileptic focus, while the anode electrode was positioned over the contralateral deltoid muscle. EEG recordings were obtained at three time points: prior to the tDCS intervention (baseline), one week after the final session, and three months post-treatment. Changes in spike-wave activity were analyzed across these recordings. Results: Group-level analyses revealed no statistically significant changes in spike-wave activity. However, individual-level assessments showed that some patients experienced a marked reduction in spike activity, while others exhibited no notable change. The results indicated substantial heterogeneity in treatment response among patients. Furthermore, the intervention was well tolerated, with no serious adverse effects reported. Conclusion: Although the effects of cathodal tDCS on spike-wave activity in patients with drug-resistant focal epilepsy varied among individuals, promising outcomes were observed in some cases. Further studies with larger sample sizes are warranted to determine the efficacy of this method and to identify patient populations that may benefit most. Keywords: transcranial direct current stimulation, neuromodulation, drug-resistant focal epilepsy