Several interactions between patient characteristics were analyzed, as mentioned in the methods section (table 2). A significant negative correlation was found between epilepsy duration and age of epilepsy onset (Pearson correlation = −0.589; p = 0.001), indicating that patients with a longer epilepsy duration were younger at epilepsy onset. We also found a negative correlation between epilepsy duration and seizure frequency (Kendall's Tau = −0.378; p = 0.009). This indicates that patients with a longer history of epilepsy had a lower seizure frequency. Epilepsy duration tended to be negatively correlated with the BSR (Kendall's Tau = −0.307; p = 0.030), indicating a lower sedation level during ECoG recordings in patients with a longer epilepsy duration. However, the significance level for this interaction was no longer reached after Bonferroni correction. No other interactions were found between the patient characteristics.
