Does early postoperative drug regimen impact seizure control in patients undergoing temporal lobe resections?

Abstract

To evaluate the impact of postoperative antiepileptic drug (AED) load on seizure control in patients who underwent surgical treatment for pharmacoresistant mesiotemporal lobe epilepsy during the first two postoperative years. 532 consecutive patients (48.7% males and 51.7% females) who underwent surgical treatment for mesiotemporal lobe epilepsy were retrospectively evaluated regarding effects of AED load on seizures control during the first 2years following epilepsy surgery. We analyzed whether postoperative increases in postoperative AED load are associated with better seizure control in patients initially not seizure free, and if postoperative decreases in postoperative AED load would increase the risk for seizure persistence or recurrence. For statistical analyses, Fisher's exact and Wilcoxon test were applied. 68.9, 64.0 and 59.1% of patients were completely seizure free (Engel Ia) at 3, 12 and 24months after surgery, respectively. Patients in whom daily drug doses were increased did not have a higher rate of seizure freedom at any of the three follow-up periods. Of 16 patients achieving secondary seizure control at 12months after surgery, only one did so with an increase in drug load in contrast to 15 patients who experienced a running down of seizures independent of drug load increases. Decreases in drug load did not significantly increase the risk for seizure recurrence. Of postoperatively seizure free patients at 3months after surgery in whom AED were consequently reduced, 85% remained completely seizure free at 1year and 76% at 1year after surgery, respectively, as opposed to 86% each when AED was not reduced (differences n.s.). Mean daily drug load was significantly lower in seizure free patients at 12 and 24months compared to patients with ongoing seizures. In this large patient cohort stratified to the epilepsy syndrome neither did a postoperative reduction in drug load significantly increase the risk for seizure relapse nor did increases in drug dosages lead to improved seizure control. Mean drug load was on average lower in seizure free- than non-seizure free patients at 12 and 24months of follow-up. Secondary seizure control after initial postoperative seizures in>90% of cases occurred as a running down, independent of an AED increase. Thus, the effect of the surgical intervention rather than the postoperative drug regimen was the key determinant for seizure control. This finding supports a curative role of temporal lobe surgery rather than an effect rendering the majority of patients' pharmacoresponsive with a critical role of the antiepileptic drug regime for seizure control.