Schizencephaly

Overview
Schizencephaly is a type of cephalic disorder.

Presentation
Schizencephaly is a rare developmental disorder characterized by abnormal slits, or clefts, in the cerebral hemispheres. Schizencephaly can be distinguished from porencephaly by the fact that in schizencephaly the cyst is lined by heterotopic grey matter while a porencephalic cyst is lined by white matter. Individuals with clefts in both hemispheres, or bilateral clefts, are often developmentally delayed and have delayed speech and language skills and corticospinal dysfunction. Individuals with smaller, unilateral clefts (clefts in one hemisphere) may be weak on one side of the body and may have average or near-average intelligence. Patients with schizencephaly may also have varying degrees of microcephaly, mental retardation, hemiparesis (weakness or paralysis affecting one side of the body), or quadriparesis (weakness or paralysis affecting all four extremities), and may have reduced muscle tone (hypotonia). Most patients have seizures and some may have hydrocephalus.

Causes
In schizencephaly, the neurons border the edge of the cleft, implying a very early disruption in development. There was once thought to be a genetic association with the EMX2 gene, although this theory has recently been disproved. Causes of this type may include environmental exposures during pregnancy such as medication taken by the mother, sickness during pregnancy, exposure to toxins, or a vascular insult. Often there are associated heterotopias (isolated islands of neurons) which indicate a failure of migration of the neurons to their final position in the brain.

Treatment
Treatment for individuals with schizencephaly generally consists of physical therapy, treatment for seizures, and, in cases that are complicated by hydrocephalus, a shunt.

Prognosis
The prognosis for individuals with schizencephaly varies depending on the size of the clefts and the degree of neurological deficit.