The long-term outcome of adult epilepsy surgery, patterns of seizure remission, and relapse: a cohort study

Background Surgery is increasingly used as treatment for refractory focal epilepsy; however, few rigorous reports of long-term outcome exist. We did this study to identify long-term outcome of epilepsy surgery in adults by establishing patterns of seizure remission and relapse after surgery. Methods We report long-term outcome of surgery for epilepsy in 615 adults (497 anterior temporal resections, 40 temporal lesionectomies, 40 extratemporal lesionectomies, 20 extratemporal resections, 11 hemispherectomies, and seven palliative procedures [corpus callosotomy, subpial transection]), with prospective annual follow-up fora median of 8 years (range 1-19). We used Kaplan-Meier survival analysis to estimate time to first seizure, and investigated patterns of seizure outcome. Findings We used survival methods to estimate that 52% (95% CI 48-56) of patients remained seizure free (apart from simple partial seizures [SPS]) at 5 years after surgery, and 47% (42-51) at 10 years. Patients who had extratemporal resections were more likely to have seizure recurrence than were those who had anterior temporal resections (hazard ratio [HR] 2.0, 1.1-3.6; p=0.02); whereas for those having lesionectomies, no difference from anterior lobe resection was recorded. Those with SPS in the first 2 years after temporal lobe surgery had a greater chance of subsequent seizures with impaired awareness than did those with no SPS (2.4, 1.5-3.9). Relapse was less likely the longer a person was seizure free and, conversely, remission was less likely the longer seizures continued. In 18 (19%) of 93 people, late remission was associated with introduction of a previously untried antiepileptic drug. 104 of 365 (28%) seizure-free individuals had discontinued drugs at latest follow-up. Interpretation Neurosurgical treatment is appealing for selected people with refractory focal epilepsy. Our data provide realistic expectations and indicate the scope for further improvements in presurgical assessment and surgical treatment of people with chronic epilepsy.