One-third of epilepsy patients develop drug resistance epilepsy (DRE), and half of them can benefit from the surgical removal of epileptic focus (EF). Neuromodulation represents the only hope to ameliorate the quality of life of the remaining patients. Cathodal transcranial direct current stimulation (ctDCS) is a techniques able to non-invasively inhibit cortical excitability, which is abnormally increased in epilepsy, but its efficacy in reducing seizures and in modulating epileptic network is still under debate.
We evaluated the efficacy of 20-min 1 mA ctDCS vs sham-tDCS in reducing seizure frequency and in modulating the functional connectivity (FC) between EF and the other cortical areas, in temporal DRE patients.
After 7 days of seizure diary, patients were randomized to either first-ctDCS or first-sham-ctDCS treatment. On day 8, patients underwent the assigned stimulation. On day 38, patients underwent the single-session opposite stimulation. 7 days after the second session, the study was concluded.
The ctDCS cathode was placed over the EF and the anode over the contralateral homologous region. Immediately before and after stimulations, a one-hour resting state closed-eyes 19-electrodes video-EEG recording was acquired.
We enrolled ten patients affected by temporal lobe DRE (4 males; 42 ± 15.7 years old; 4 symptomatic and 6 cryptogenic;5 right EF).
ctDCS reduced the percent weekly SF more than sham stimulation (-71 ± 33% ctDCS vs 25 ± 125% sham; Z = -2.201, p = 0.028). EA changes did not differ between ctDCS respect to sham-ctDCS (p > 0.200 consistently). No patients reported worsening of SF or of seizure intensity.
FC changed after real stimulation in all patients and involved the focus in 71% of the new connections. No FC change was found after sham.
we demonstrated that an individualized ctDCS reduced seizure frequency in temporal DRE without any safety concern. FC changes may help to explain ctDCS effects on DRE patients.