Topical Review: Schizencephaly: Clinical Spectrum, Epilepsy, and Pathogenesis

Abstract

After almost 60 years since the original description, we have reviewed the results of the more recent studies on schizencephaly in an attempt to delineate its imaging and clinical spectra of presentation and to point out the still unsettled controversies on its pathogenesis. The clinical picture is mainly based on the presence of motor deficits and mental retardation, but the severity of the clinical picture is extremely variable, mainly related to the size and location of the clefts and to the presence of associated cerebral malformations. By contrast, the outcome of epilepsy, which is present in about half of the cases and drug resistant in a third, is not strictly related to the severity of the malformation. Some clinical and functional magnetic resonance imaging studies have suggested that, beside the features of the anatomic damage, the functional reorganization of a malformed and unaffected cortex is most likely crucial in determining the clinical outcome. Review of the genetic studies and the more recent personal data suggests that the role of the EMX2 gene in schizencephaly, if any, is restricted to a minority of cases, leaving the etiopathogenesis of this brain malformation still a matter of study and debate. ( J Child Neurol 2005;20:313—318).

Aspectos clínicos em 16 pacientes com diagnóstico tomográfico de esquizencefalia

“…Although clefts in three of our patients were small, the clinical feature was severe as a result of the presence of other cerebral anomalies associated with schizencephaly. Therefore, our data suggest that the clinical feature is also related to the presence of other central nervous system anomalies, corroborating the findings of Granata et al (13) . The clinical feature was in agreement with data reported by other authors (6,9,14,15) , with the majority of patients presenting motor deficit and neuropsychomotor development delay (8,9) .…”

Neuronal migration disorders: clinical, neuroradiologic and genetics aspects

“…The cleft is often found in perisilvian areas (11). Two anatomical presentation could be distinguished: open (walls of cleft are entirely divided by cerebrospinal fluid) and closed (walls of cleft are incompletely divided) lip; however the spectrum is various, ranging from small, unilateral fusedlip clefts to large, bilateral open lips.…”

A Rare Case of Schizencephaly

“…(7) Schizencephaly is also considered a disorder of cortical organization because the cortex surrounding the cleft is polymicrogyric. [1) An important role in genesis of Schizencephaly is mutation in homeobox gene EMX2, a gene coding for transcription factor involved in expression of the gene. Several studies evidenced data suggesting that EMX2 gene may be involved in the modulation of cell proliferation of cortical neuroblasts and/or cell migration of postmitotic neurons, as it is known that these cells reach their final destination in the mature cortex according to their generation date.…”