Abstracts

Rationale: There have been few studies documenting the efficacy and outcomes of hemispherectomy in children. Methods: This is a chart review of 23 children (11 boys, 12 girls), obtained through our epilepsy surgery database, who underwent functional hemispherectomy from 2003 to 2009. All had presurgical evaluation including brain MRI and long term EEG monitoring. Preoperative information included development history, age at surgery and seizure onset, handedness, seizure type, treatments tried prior to surgery, EEG, MRI and functional neuroimaging results. Perioperative data included blood loss during surgery and number of hospital days. Postoperative data included surgical complications, pathology, and seizure frequency after 6 months, 1 year, 2 years and 4 years. Results: Seizure onset ranged from 1 day to 120 months (mean 20.1 months) and age at surgery ranged from 1 month to 242 months (mean 80 months). Seizure types ranged from infantile spasms (n=9), simple partial seizures (n=2), and complex partial seizures (n=17). Two patients presented with epilepsia partialis continua (EPC) and focal electrical status epilepticus of sleep (ESES). Three underwent hemispherectomy urgently (1 with EPC, 1 with spasms and 1 with complex partial seizures). The median number of anticonvulsants tried prior to surgery was 3. One had a vagal nerve stimulator placed and 3 had tried dietary therapy prior to surgery. All had ictal EEG onsets on the side of resection. One had a normal preoperative MRI while the rest had lesions on the side of the hemispherectomy. Hemispherectomy was performed on the left in 12 and right in 11. Three patients had focal resections that were extended to a hemispherectomy due to continued seizures. No patient returned to surgery for further disconnection after the hemispherectomy was completed. One death was reported from stroke and herniation in the perioperative period. Ventriculoperitoneal shunt placement (n=9) was the only other surgical complication seen. Pathology ranged from cortical dysplasia (n=13), hemimegalencephaly (n=4), gliosis from stroke (n=11), encephalitis (n=1) and Sturge Weber (n=2). Dual pathology of gliosis and cortical dysplasia were seen in 2. Concordant mesial temporal lobe sclerosis was found on pathology in 2 patients who had ESES or EPC. Seizure freedom was obtained in 17/22 patients with a follow-up of 3.5 months to 4 years (mean 19 months). Two patients had over 50% improvement of seizures and 3 had 90% improvement of seizures. Conclusions: 1) 77% of patients were seizure free after hemispherectomy. 2) No difference was noted in seizure outcome depending on pathology or surgical complications. 3) Worse seizure outcome rates were seen in patients who had infantile spasms, prolonged seizure duration prior to surgery, increased number of anticonvulsants or trial of non-medication treatments prior to surgery. 4) Extension of a previous resection to a hemispherectomy can improve seizure outcome as seen in 3 patients 5) Post operative complications such as ventriculoperitoneal shunt do not effect seizure frequency in the long term.