Surgical outcome and contributing presurgical evaluations in children with magnetic resonance imaging-negative epilepsy and periodic seizure cycles.

BACKGROUND: The identification of surgical candidates is a critical issue in patients with magnetic resonance imaging (MRI)-negative drug-resistant focal epilepsy and latent accompanying resectable lesions, such as focal cortical dysplasia (FCD). Recently, periodic seizure cycles have been associated with FCD in both patients with MRI-positive and MRI-negative epilepsy. We investigated the presurgical evaluation and postsurgical outcome of patients with MRI-negative epilepsy with FCD and a history of periodic seizure cycles.

METHODS: We retrospectively reviewed the characteristics of presurgical evaluation and postsurgical seizure outcome in 14 children with MRI-negative drug-resistant focal epilepsy and a history of periodic seizure cycles. All the patients had FCD histopathologically.

RESULTS: The mean age at epilepsy surgery was 7.7 ± 4.7 years (0.7-16.1 years). Favorable postsurgical seizure outcome (ILAE classes 1-3) was obtained in 10 (71 %) patients five years after surgery. The relative risk of the complete concordance between imaging findings and resected area for five-year seizure freedom was 2.25 in positron emission tomography (PET) and 2.22 in subtraction ictal single-photon emission computed tomography co-registered to MRI (SISCOM), and 1.86 in magnetoencephalography (MEG).

CONCLUSION: All the children with MRI-negative focal epilepsy and a history of periodic seizure cycles were turned out to have FCD pathologically, and are good surgical candidates. Favorable seizure outcome can be expected in such patients when resective epilepsy surgery is planned based on presurgical evaluation with PET or SISCOM.