Congenital arachnoid cyst of the lateral ventricles in children.

The authors report a series of three children with symptomatic congenital arachnoid cyst of the lateral ventricles. Presenting symptoms consisted of macrocephally, delay in psychomotor development, and seizures. CT findings were of a well-defined cystic lesion placed in the atrium of the lateral ventricle. One child was treated by direct cyst exposure and cysto-peritoneal shunt. The other two were treated with ventriculo-cysto-peritoneal shunts; in one of these, we used a ventriculoscope both for cyst fenestration and for accurate shunt placement. The origin of intraventricular arachnoid cysts seems to be secondary to the displacement of arachnoid cells by the vascular mesenchyma, through the choroid fissure, during the process of choroid plexus development.