Subacute neocortical stimulation (SNCS) and its effects on epileptic activity in adults and children diagnosed with focal cortical dysplasia (FCD)

Abstract Background Chronic intracranial electrical stimulation is now widely used as treatment for drug resistant epilepsy. Subacute neocortical stimulation (SNCS) can also be performed during recordings with intracranial electrodes, but its diagnostic value remains largely unknown. Methods We assessed the effects of SNCS on the frequency of seizures and epileptiform discharges (EDs) during 290 hours of iEEG-recordings from 12 patients (6 adults, 6 children) with epilepsy secondary to focal cortical dysplasia (FCD). Results In 9/12 patients, SNCS periods showed decreased seizure-frequency (Median -73%, p = 0.0093). At baseline, incidence of EDs were correlated with seizure-frequency (Spearman r = 0.59). However, this correlation disappeared during SNCS and significant de- or increase in the incidence of EDs was observed. In addition, there was a trend towards greater reduction in seizure-frequency during SNCS in patients who underwent surgery. Conclusion In summary, SNCS can reduce seizure-frequency and changes ED-frequency. The variability in ED changes may be explained by different effects of SNCS depending on electrode location. The magnitude of seizure reduction during SNCS suggests that this technique could contribute to the preoperative assessment in epilepsy surgery.