9 Schizencephaly

CASE 9

Clinical Presentation

A 2-year-old child presents with partial-onset seizures, microcephaly, severe developmental delay, and quadriparesis.

Figure 9A

Figure 9B

Figure 9C

Figure 9D

Radiologic Findings

Axial T1- (Fig. 9A), axial T2- (Fig. 9B), and coronal T2-weighted (Fig. 9C) images show bilateral, asymmetrical, large open clefts in both hemispheres. The surface opening is well depicted on the surface rendering of the left hemisphere (Fig. 9D). The septum pellucidum is absent. The clefts are lined with a somewhat thick, irregular, polymicrogyric cortex that extends to the lateral ventricles. The cortex surrounding the clefts also looks polymicrogyric. Surface rendering shows the cortical sulci converging toward the defect. The corpus callosum is thin posteriorly, presumably by lack ofcorresponding cortex with which to connect. Over the fluid-filled cavity of the large cleft on the right, the vault is thinned and expanded.

Diagnosis

Bilateral schizencephaly, open-lipped type

Differential Diagnosis

Destructive porencephalic cysts, either posthemorrhagic (juxtaventricular) or ischemic (fitting an arterial, usually middle cerebral, territory). Schizencephaly is thought to develop early in gestation, whereas destructive porencephalic cysts develop in the last trimester. The walls of destructive porencephalic cysts are made of white matter, without any cortical covering.
Hydranencephaly with some residual supratentorial tissue in distribution of anterior and posterior cerebral arteries is generally assumed to be an extreme form of bilateral porencephaly, but it is difficult to differentiate from severe schizencephaly.
Arachnoid cysts, usually in the anterior insular region, are strictly extracerebral.

Discussion

Background

Schizencephaly is defined as a congenital brain cleft, which extends from the pial to ventricular surface (transmantle defect) and is lined by dysplastic cortex joining the lateral ventricles.

Etiology

The etiology is usually unknown.

Most cases are idiopathic.
Rare familial cases have been observed, and a germline mutation in the EMX2 gene has been detected in one.
Observed as an occasional complication of intrauterine cytomegalovirus (CMV) infection.
Trauma in early pregnancy has been postulated in some instances.

Clinical Findings

The clinical finding of schizencephaly is cerebral palsy in which the psychomotor defect is related to the location of the lesion. Epilepsy develops in ~50% of cases. The severity of clinical presentation is dependent on the extent of the abnormality.