Abstracts

Rationale: Approximately 10% of children with epilepsy will continue to have seizures despite optimal medical management with antiepileptic drugs (Berg at al. Early development of intractable epilepsy in children: prospective study; Neurology, 56: 1445-1452, 2001). The localization of epileptogenic cortex remains challenging in order to proceed for epilepsy surgery. There has been limited data describing the early clinical course of children who underwent subdural electrode placement to localize the epileptogenic cortex. Methods: This is a retrospective study to review existing data of patients 1-20 years old (n: 23, mean age: 12, M/F: 14/11) who underwent epilepsy surgery evaluation with placement of subdural electrodes for medically refractory epilepsy in Morgan Stanley Children's Hospital (2010-2013). Medically refractory epilepsy was defined as either inadequate seizure control despite appropriate medical therapy with at least 2 anti-epileptic drugs in maximally tolerated doses for 18 months to 2 years or adequate seizure control accompanied by unacceptable drug-related side effects. All patients underwent craniotomy for the placement of subdural grids to localize epileptogenic cortex. Results: Twenty four admissions were reviewed. One patient underwent craniotomy twice for evaluation. All patients were admitted to pediatric intensive care unit (PICU) and bed side c-EEG (continuous) monitoring was initiated soon after the placement of subdural electrodes. Subgaleal drain (JP drain or hemovac) was placed in 15 patients in order to eliminate blood and fluid collection around the craniotomy site. The length of hospital stay between the subdural electrode placement and final craniotomy ranged from 5 days to 26 (mean: 9.5 days). Focal habitual seizures were recorded in 21 patients. In 7 patients (29%), seizures were captured within the first 24hrs of PICU stay. None of the patients experienced Status Epilepticus. The most common post-operative complications were face swelling (n: 8, 33.3%), intracranial subdural hemorrhage (n: 3, 12.5%), and transient fever (n: 3, 12.5%). One patient developed subgaleal hematoma. Ony two patients who did not have subgaleal drain underwent clot evacuation, one for subgaleal hematoma and the other one for subdural hemorrhage. Face swelling was seen less often in patients who had subgaleal drain placement (3/15 with drain, 5/9 without drain). Twenty one patients underwent resection of the epileptogenic cortex. Two patients did not have resection due to the localization of epileptogenic focus to the eloquent cortex in one and the contralateral hemisphere in the other. Conclusions: Subdural electrode monitoring is a useful procedure in the localization epileptogenic cortex. Very few patients (8.3%) experienced a major complication that required medical or surgical intervention. This study also points to the importance of early bedside continuous EEG recording soon after subdural electrode placement in order to capture habitual seizures.