A Distinct Asymmetrical Pattern of Cortical Malformation: Large Unilateral Malformation of Cortical Development with Contralateral Periventricular Nodular Heterotopia in Three Pediatric Cases

Abstract

To describe a distinct asymmetrical pattern of cortical malformation with large focal malformations of cortical development (MCDs) and contralateral periventricular nodular heterotopia (PNH). We identified three patients with epilepsy and focal EEG abnormalities. Each patient underwent 1.5-Tesla magnetic resonance imaging (MRI) to obtain sagittal T1-weighted, axial fluid-attenuated inversion recovery (FLAIR), fast spin-echo (FSE) T2-weighted, and coronal fast spin-echo inversion recovery (FSEIR) T2-weighted images; coronal spoiled gradient recalled (SPGR) T1-weighted images were obtained in two cases. Patient 1, an 18-year-old right-handed man, had a 4-year history of intractable seizures. MRI revealed a right frontal subcortical heterotopia (SH) and a single left anterior PNH. Patient 2, a 10-year-old left-handed boy, had a 4-year history of epilepsy. MRI revealed a large region of SH in the left temporal, parietal, and occipital lobes and three right-sided PNH. Patient 3, a 16-month-old girl, had medically refractory infantile spasms. MRI revealed a large MCD in the left parietal lobe with contiguous underlying periventricular heterotopia as well as a small contralateral PNH. These cases together illustrate a distinct asymmetrical pattern of a large focal MCD with small contralateral PNH. The asymmetrical involvement of the two hemispheres suggests that the stage of maximal disruption of cortical development may differ between the two hemispheres. Further study into the mechanisms underlying such asymmetrical patterns of cortical malformation should enhance our understanding of cortical development as well as hemispheric lateralization.