Congenital unilateral hydrocephalus.

An 848-g infant delivered after a 30-week gestation had been diagnosed by ultrasonic examination as having a unilateral ventriculomegaly from the 29th week of gestation. Computerized tomography (CT) demonstrated a greatly dilated right lateral ventricle with no apparent space-occupying lesion within the ventricle and no passage of the contrast medium (metrizamide) through the foramen of Monro. The child was diagnosed as having unilateral hydrocephalus due to congenital obstruction of the foramen and underwent a ventriculoperitoneal shunt operation on day 49 (37 weeks and 5 days of amended gestation age; 1,420 g body weight). The postoperative course was uneventful and the patient was discharged on day 126 with no marked developmental retardation. Angiography carried out at 8 months postpartum revealed displacement and hypoplasia of the deep cerebral veins. The pathogenesis and treatment of unilateral hydrocephalus are discussed.