Safety and Long-term Seizure-Free Outcomes of Subdural Grid Placement in Patients With a History of Prior Craniotomy

Abstract

Patients who continue or begin to have seizures after brain surgery pose significant challenges and often require an invasive electroencephalographic evaluation before reoperation for drug-resistant epilepsy. The safety and seizure-free outcomes associated with subdural grid (SDG) implantation in patients with a prior craniotomy are important for both surgeon and patient to understand before pursuing further surgery. To evaluate the safety of SDG placement and subsequent resective surgery in patients with prior craniotomy and to characterize the seizure outcomes and their predictors after resective epilepsy surgery in this unique cohort. We retrospectively reviewed all intractable focal epilepsy patients with a history of craniotomy who underwent SDG insertion between 2000 and 2012 at our institution. A minimum follow-up of 6 months was required. End points analyzed included complications related to each surgery and Engel classification at the last follow-up. The mean age of seizure onset was 15.9 years, and the mean age for the initial surgery was 24.2 years. Only 3 patients began having seizures after the initial surgery. Seven patients (7%) had a complication associated with the SDG placement, and 15 (14%) had a complication after subsequent resection, which was equivalent to the initial procedure. Forty-eight patients (44%) were in Engel class I at the last follow-up. Freedom from seizures was predicted by ictal onset at the edge of the original surgical bed, particularly in patients with lesional epilepsy. Surgical intervention with SDG monitoring does not appear to be associated with increased risk of complications in epilepsy patients with a history of prior craniotomy, and rates of freedom from seizures in this challenging group are favorable.