Outcome analysis of surgical resections in patients with refractory epilepsy—A review of 15-year experience at a single center

Abstract

Objective To summarize the epileptogenic localizations, pathological findings and long-term surgical outcomes of patients with refractory epilepsy at a single center during past 15 years. Methods A total of 2 424 patients who underwent epilepsy surgeries at Department of Functional Neurosurgery between April 2001 and December 2016 were included in this retrospective study. The traits of epileptogenic localization were analyzed. Outcomes of all patients who were followed up longer than 1 year post surgeries were studied in two stages, and the rate of seizure free was calculated. Results Among all 2 424 patients, 1 299 (53.6%) had obvious lesions on MRI. There were 1 007 (41.5%) patients who underwent intracranial electrode placement and 65.5% of those had no definite lesions on MRI. There were 1 030 (42.5%) cases who were diagnosed as temporal lobe epilepsy (TLE) and 1 394 (57.5%) diagnosed as extratemporal lobe epilepsy (ETLE). The common pathological types included focal cortical dysplasia (37.5%, 909), mesial temporal sclerosis (17.7%, 429), ulegyria (15.7%, 381) and low grade tumor (9.2%, 223). There was a double pathological change in 303 (12.5%) patients. A total of 1 424 (59.0%) patients were followed up for more than 1 year post surgery. At the first stage of follow-up (April 2001 to July 2012), 846 patients completed follow-up lasting at least 1 year. The seizure-free rate was 64.7% (547/846) at 1 year, 52.5% (241/459) at 3 years and 49.6% (119/240) at 5 years post surgery. For the patients with TLE, the seizure-free rate was 57.9% (210/363) at 1 year, 57.8% (108/187) at 3 years and 56.3% (58/103) at 5 years post surgery. For the patients with ETLE, the seizure-free rate was 59.4% (287/483) at 1 year, 47.8% (130/272) at 3 years and 46.7% (64/137) at 5 years post operation. At the second stage of follow-up (August 2012 to September 2015), 578 patients completed follow-up lasting at least 1 year. The seizure-free rate was 64.7% (374/578) at 1 year and 57.3% (133/232) at 3 years post surgery. For the patients with TLE, the seizure-free rate was 71.4% (187/262) at 1 year and 66.4% (64/95) at 3 years post operation. For patients with ETLE, the seizure-free rate was 59.5% (188/316) and 51.1% (70/137) at 1 year and 3 years post operation respectively. However, the difference in the seizure free rate was significant only at the first year post surgery in the patients with TLE between the 2 stages (57.9% vs. 71.4%, P=0.001), and there was no significant difference afterwards. Conclusions Long-term intracranial recording seems to be indispensable for identification of epileptogenic focus for some patients. Although surgical efficacy might decrease to some extent with extension of postoperative time, surgical treatment is beneficial and postoperative outcome is relatively stable for patients with either temporal or extratemporal epilepsy. Key words: Epilepsy; Neurosurgical procedures; Treatment outcome; Temporal lobe epilepsy; Extratemporal lobe epilepsy