Age-related MR characteristics in mild malformation of cortical development with oligodendroglial hyperplasia and epilepsy (MOGHE).

BACKGROUND: Mild malformation of cortical development with oligodendroglial hyperplasia and epilepsy (MOGHE) is a newly described, rare histopathologic entity detected in resected brain tissue of patients with refractory epilepsies. It shows a predominantly frontal localization causing a difficult-to-treat epilepsy with onset usually in early childhood. Histologically, MOGHE is characterized by blurred gray-white-matter boundaries with increased numbers of heterotopic neurons in the subcortical white matter and increased density of oligodendroglia. Little is known, to date, about radiologic features of MOGHE. Here, we report typical and age-related magnetic resonance (MR) characteristics of MOGHE. PATIENTS AND METHODS: Retrospective analysis of 40 preoperative MR images of 25 pediatric patients with MOGHE (m/f: 13/12) who underwent epilepsy surgery at a median age of 9.3 years at our center between 2003 and 2018. Median age at magnetic resonance imaging (MRI) was 5.2 years (1.5-20.7 years). RESULTS: Two MR subtypes were found: subtype I with an increased laminar T2 and fluid attenuated inversion recovery (FLAIR) signal at the corticomedullary junction and subtype II with reduced corticomedullary differentiation because of increased signal of the adjacent white matter. Distribution of subtypes was age-related, with subtype I occurring between 1.5 and 5.1 years (median 2.6 years) and subtype II between 3.4 and 20.7 years (median 14.1 years). In one patient, MRI at the age of 2.7 years showed subtype I but had converted to subtype II by the age of 16 years. Histology revealed that in addition to the above mentioned typical findings of MOGHE, patchy areas of reduced density of myelin in 6 of 7 patients presenting subtype I out of 14 patients in which retrospective analysis regarding myelination was accessible. CONCLUSION: Magnetic resonance characteristics in patients with MOGHE are age-related and seem to change from subtype I to subtype II probably because of maturational processes between 3 and 6 years. Patchy areas of hypomyelination in histology seem to disappear during brain maturation and may therefore represent the histologic correlate of laminar T2 and FLAIR hyperintensities in subtype I. This article is part of the Special Issue "Individualized Epilepsy Management: Medicines, Surgery and Beyond".