Abstracts

Relapses sometimes happen for the first time many years after epilepsy surgery. Although late recurrences are thought to carry a more benign prognosis than early recurrences, it is important to define the clinical course when late seizures occur. We wished to determine prognosis when the first postoperative seizure occurs more than 5 years after surgery. Also, we assessed the relationship between antiepileptic drug (AED) use and relapse. Patients who had resective epilepsy surgery were prospectively registered in a database. Follow-up was conducted by office visit or phone contact. For inclusion in this analysis, patients were required to be seizure free, with or without auras, for the first 5 years after surgery. Terminal remission was defined as absence of seizures in the final year of follow-up. Therefore, to be included, patients must have had at least one year of follow-up after the initial recurrence if they relapsed. Age, gender, type of surgery, medication status at first relapse and last visit, and seizure history were registered. Non-parametric statistics were used to compare patient groups. 159 patients were seizure free for at least 5 years after surgery. 74 were male and 85 were female, mean age 33.2 years at surgery (range 14 - 66 yrs). 141 had temporal lobectomy (ATL) and 18 had extratemporal resection (ETR).
32 patients (20%) had at least one recurrent seizure (mean follow-up 12 yrs). 26 had ATL, and 6 had ETR. Time to initial recurrence ranged from 5.3 to 15.1 years after surgery. At the time of first recurrence, 17/32 (53%) patients were on AEDs and 15 (47%) were not on AEDs. 30 of the 32 patients with recurrence had follow-up of at least one year after the initial recurrence. 16 patients (53%) were in terminal remission, 9 (30%) had rare or nocturnal seizures, 4 (13%) had at least an 80% reduction compared with preoperative seizure frequency, and one (3%) had pseudoseizures. Of the patients in terminal remission, 13 had only one seizure, and 3 patients had two or three seizures.
127 patients remained seizure free during follow-up (mean follow-up 8.8 yrs). Of these, 115 patients (91%) had ATL and 12 had an ETR. Type of procedure did not influence likelihood of recurrence. 99 seizure free patients were followed for at least 6 years after surgery (to allow for comparison to patients with recurrences). Among these patients, 50 are currently off medication and 49 are taking AEDs. Hence, the proportion of patients who relapsed was similar in those taking and not taking medication. Patients who are seizure free for the first 5 years after epilepsy surgery are still at significance risk for seizure recurrence. Relapses appear to be isolated events in many patients, who then enter remission. Location of surgery and medication usage were not associated with increased risk of late relapse.