Radiologic Findings: On the CT of the brain nodular irregularity of both lateral ventricular walls suggestive of heterotopia. T1 weighted axial images and gradient echo volume sagittal images were obtained. There is a gray matter lined cleft extending from the level of the parieto-occipital junction to the occipital horns of the lateral ventricles. There is marked gray matter heterotopia lining the occipital horns, atria, and the bodies of the lateral ventricles bilaterally. The gyral pattern of the occipital and pareietal lobes are abnormal with a thickened nodular pattern suggesting areas of polymicrogyria.
Diagnosis: Bilateral closed-lip schizencephaly
Discussion: Schizencephaly, also known as agenetic porencephaly, refers to gray matter lined clefts that extend through the entire hemisphere from the ependymal lining of the lateral ventricles to the pial covering of the cortex. The gray matter lining is dysplastic. The clefts can be unilateral or bilateral and are commonly located near the pre- or post-central gyri.
Two types of schizencephaly are identified for prognostic purposes. In closed-lip schizencephaly, the cleft walls oppose each other causing obliteration of the CSF space within the cleft. In open-lip schizencephaly, CSF fills the cleft from the lateral ventricles to the subarachnoid space that surrounds the hemispheres. Patients typically present with seizures, hemiparesis, and some degree of developmental delay.
Imaging studies demonstrate a gray matter cleft through the affected hemisphere with an irregular gray matter - white matter junction. The cortex adjacent to the cleft usually demonstrates cortical dysplasia. Cortical dysplasia can also be seen in the contralateral hemisphere with unilateral schizencephaly. The cavum septum pellucidum is absent in 80-90% of patients with schizencephaly.
Patients with bilateral clefts may be severely retarded. They present with early onset of epilepsy, severe motor abnormalities, and frequently blindness. The blindness is a result of optic nerve hypoplasia, which is seen in one third of patients with schizencephaly.
References: Barkovich AJ. Pediatric Neuroimaging.