Clinical characteristics and surgical outcomes in children with mild malformation of cortical development and oligodendroglial hyperplasia in epilepsy

OBJECTIVE: Mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE) is a new and rare histopathological entity of cortical developmental malformations. The clinical characteristics of MOGHE remain challenging. METHODS: Children with histologically confirmed MOGHE were retrospectively studied. The clinical findings, electroclinical and imaging features, and postoperative outcomes were analyzed, and previously published studies were reviewed up to June 2022. RESULTS: Thirty‐seven children were included in our cohort. Clinical characteristics included early onset in infancy (94.6% before 3 years), multiple seizure types, and moderate or severe delay. Epileptic spasm is the most common seizure type and initial manifestation. The lesions were mainly multilobar (59.5% multiple lobes and 8.1% hemispheres), and predominance in the frontal lobe was observed. The interictal EEG pattern was circumscribed or widespread. The prominent MRI characteristics were cortical thickening, cortical/subcortical hyperintense T2/FLAIR signal, and blurring at the GM and WM transition. Among the 21 children followed up for more than 1 year after surgery, 76.2% were seizure‐free. Preoperative interictal circumscribed discharges and larger resections were significantly associated with a good postoperative outcome. The clinical features of 113 patients in the reviewed studies were similar to those we reported, but the lesions were mainly unilobar (73.5%) and Engel I was achieved in only 54.2% after surgery. SIGNIFICANCE: Distinct clinical characteristics in MOGHE, especially age at onset, epileptic spasm, and age‐related MRI characteristics, can help in early diagnosis. Preoperative interictal discharge and surgical strategy may be predictors of postoperative outcomes.