Efficacy of cathodal transcranial direct current stimulation in drug-resistant epilepsy: a proof of principle.

It has been proved that Transcranial DCS (tDCS) can modulate cortical excitability, enhancing or decreasing, respectively by anodal or cathodal polarity. The short-term and lasting alterations induced by tDCS are strictly related to the charge density, duration of stimulation and the depth of neuron below the skull. Epilepsy represents a pathophysiological model of unbalanced relation between cortical excitation and inhibition. In this line, tDCS can be exploited to counterbalance the neuronal hyper-excitation through electric neural modulation. This paper aims at providing the efficacy of cathodal tDCS in reducing seizures' frequency in drug-resistant focal epilepsy. The study was single blind and sham-controlled with an observation period of one month during which the patients or the caregivers provided a detailed seizures' calendar (frequency as n°/week; basal, post sham and post tDCS). Patients received sham or real tDCS treatment on the 8th and 22th days. Two patients affected by focal resistant epilepsy were enrolled. They both underwent a consistent reduction of the seizures'frequency: about 70 % for Patient 1 and about 50% for Patient 2. This study represents the proof that cathodal tDCS may be efficient in reducing seizures'frequency in focal resistant epilepsy.