Electrical cortical stimulation for refractory focal epilepsy: A long-term follow-up study

To report the long-term seizure control and safety of open-loop electrical cortical stimulation in patients with refractory focal epilepsy of diverse etiologies.

Six patients who received a therapeutic trial of cortical stimulation were included retrospectively. The frequency of seizures was recorded before and after implantation. Surgical procedure- and stimulation-related adverse effects were also recorded.

The mean reductions in seizures were 61% at 1 year, 68% at 2 years, and 80% at 3-7 years post-implantation. The median follow-up time was 54 months (range 36-156 months). The etiologies of epilepsy included polymicrogyria in two patients, post-traumatic in one patient, and periventricular heterotopia, post-encephalitis, and familial lateral temporal lobe epilepsy in the remaining three patients. Status epilepticus stopped immediately after stimulation in three patients with focal status epilepticus or epilepsia partialis continua at baseline, with a long-term reduction in seizures of more than 90% and improvements in conscious level. Tissue incompatibility with the connection wire was noted in one patient, which subsided after the system was removed.

Open-loop cortical stimulation of epileptic foci improved seizure control in our patients with refractory focal epilepsy of diverse etiologies. Electrical cortical stimulation stopped epilepsia partialis continua/focal status epilepticus immediately after the intervention and exhibited a sustained effect in reducing seizures. No procedure-related complications were observed. Further case cohort studies are needed to clarify which patients respond to open-loop cortical stimulation.