Unusual mesencephalic developmental venous anomaly causing obstructive hydrocephalus due to aqueductal stenosis.

Developmental venous anomalies (DVAs) are benign vascular malformations that rarely become symptomatic. They are anatomical variations of the venous drainage system and most are incidentally discovered. Mechanical (obstruction and compression of cerebral and neural structures) and flow-related pathological mechanisms have been described in rare cases of symptomatic DVAs. The authors present the case of a 10-month-old boy with a mesencephalic DVA compressing the aqueduct and causing occlusive hydrocephalus. Endoscopic inspection confirmed the venous malformation causing aqueductal stenosis. The authors successfully performed endoscopic third ventriculostomy, resulting in decrease in the size of the ventricles. At the 6-month follow-up after surgery, the patient had significantly progressed in his psychomotor development. One year postsurgery the patient is doing fine, with no neurological or developmental deficits.