Abstracts

Rationale: Refractory epilepsy in children is a common problem for which surgery offers a potential cure. Many children who undergo subdural grid and strip placement to better define the epileptic zone and map eloquent cortex do not receive continuous electroencephalogram (EEG) monitoring in the first 24 hours following surgery. It has been proposed that seizures in the first 24 hours following surgery are different from a patient’s habitual seizures and therefore, should not be used to plan for a cortical resection. If seizures within the first 24 hours were consistent with a patient’s habitual seizure using these seizures in surgical planning may shorten the time grid and strips were left in place and decrease possible morbidity. Methods: During the 18 month period from January 1, 2006 until June 1, 2008, 30 children underwent subdural grid and strip placement at Children’s Hospital of Pittsburgh. Following surgery all patients had continuous digital EEG monitoring while in the Intensive Care Unit until transfer to the Epilepsy Center 24 hours after surgery. Thirteen patients had seizures within the first 24 hours and then had additional seizures in the following 7-10 days of monitoring. All 13 patients underwent a surgical resection at the end of the monitoring period. The seizures recorded in the first 24 hours were reviewed with onset region determined and then compared to those seizures occurring after the first 24 hours to determine if the early seizures were consistent with the patient’s habitual seizures. Results: Thirteen patients aged 5-18 years had seizures in the first 24 hours following surgery and were included in the study. A total of 39 seizures were recorded ranging from 1-6 per patient, all of the seizures were defined as typical or typical but more mild than usual by the patient's family. At least two epileptologists reviewed all of the recorded seizures to determine onset. A cortical resection was performed on all patients, including 6 temporal, 2 frontal, 2 parietal, 1 occipital, 1 frontotemporal and 1 parietoccipital. Outcomes based on the Engel class scale for these patients were 11 patients Engel class I (84.6%) and 2 patients Engel class II (15.4%). Follow-up period ranged from 6 months to 2 years. In all 13 patients with seizures recorded in the first 24 hours, the onset of these early seizures was identical to those seizures recorded later in monitoring period. Conclusions: Seizures recorded in the first 24 hours following grid and strip placement were consistent with a patient’s habitual seizures and can be used in planning for a cortical resection. All of our patients’ seizures in the first 24 hours had an identical onset to the seizures recorded later during the monitoring period. The use of these early seizures may shorten the time required for monitoring after subdural grids have been placed. We therefore recommend EEG monitoring in the first 24 hours following subdural grid/strip placement.