Seizure outcome after extratemporal epilepsy surgery in childhood

Aim The aim of the study was to describe seizure outcome following surgery for focal extratemporal epilepsy and identify factors associated with prolonged postsurgical freedom from seizures. Method In this retrospective cohort study, children with drug-resistant focal extratemporal epilepsy were treated surgically and followed up in a single tertiary care centre between 1997 and 2008. Results Eighty children were identified for inclusion in the study (42 males, 38 females; median age 9y 1mo, range 3mo18y 7mo). The aetiology was identified as focal cortical dysplasia (n=37), low-grade tumour (n=22), tuberous sclerosis (n=9), or non-specific (n=12). Children were followed for a median of 3 years 1 month (range 8mo10y 7mo) after surgery. Overall, at last follow-up, 50% of the children had been completely seizure free since surgery (Engel class Ia); of these 40 individuals, 15 had discontinued all antiepileptic drugs. Several presurgical factors were associated with a favourable outcome. However, after controlling for confounding factors, aetiology appeared to be the only determinant of long-term seizure outcome as non-specific lesion pathology was associated with seizure recurrence (hazard ratio 10.43; 95% confidence interval 3.2633.39). Interpretation In 50% of cases, children with surgically treated drug-resistant extratemporal epilepsies have an excellent long-term outcome. The aetiology of the epileptogenic lesion appears to be the only significant determinant of surgical outcome in this population of children. It is difficult to correctly identify non-specific pathology on presurgical magnetic resonance imaging.