Mild malformation of cortical development : clinical feature and surgical outcome related to histopathology

Abstract

Mild malformation of cortical development (mMCD), which classified by the Palmini et al. could not have mature clinical impact until now. This study aimed to show the clinical feature and surgical outcome associated with pathological finding, mMCD. Thirty-six of children and adolescents who underwent resective epilepsy surgery with confirmed mMCD by pathological finding were reviewed. All the patients were medically intractable to 2 or more antiepileptic drugs (AEDs) and/or ketogenic diet and were followed up for more than 2 years after surgery. Central nervous system comorbidities (such as prematurity, asphyxia, bleeding, hydrocephalus, early CNS infection and traumatic brain injury) were seen in 9 cases (25.0%). Twenty six cases (72.2%) presented as childhood onset epileptic encephalopathy, further divided by 20 Lennox-Gastaut syndrome and 6 West syndrome, while 10 cases (27.8%) presented as focal epilepsy (8 cases; extratemporal lesion, 2 cases; temporal lesion). For the age of seizure onset, 18 cases (50.0%) had started seizure before the age of 1 year, and 22 cases (61.1%) had seizures before the age of 2 year. Seventeen cases (47.2%) had non focal MRI abnormalities. The most frequent surgical procedure was 22 cases (61.1%) of multilobar resections, followed by 10 cases (27.8%) of unilobar resection, and 4 cases (11.1%) of posterior quadrantectomy along with frontal lobectomy. The median postoperative followed-up duration was 4.8 years and final surgical outcome including reoperations, 22 cases (61.1%) had Engel I outcome. Six (27.3%) out of 22 Engel I cases were off all the AEDs. This study identified mMCD as an important pathologic finding related to comparable degree of epileptogenicity and supported the certainty of focal pathology of mMCD, could be successfully treated by resective surgery.