Double compartment hydrocephalus--a new clinical entity.

We are reporting eight patients who demonstrated double compartment hydrocephalus, i.e., supratentorial and infratentorial hydrocephalus in clinical sequence and separately. One infant with veil occlusion of the aqueduct was operated on to remove the veil and then later demonstrated panhydrocephalus. Six patients had been treated months to years earlier by the performance of a ventriculoperitoneal shunt for aqueductal hydrocephalus and then developed characteristic cerebellar-brain stem deficits from 4th ventricle enlargement. The work-up included computed tomographic scan, air study, isotope cerebrospinal fluid flow study, and direct 4th ventricle pressure studies. Operation with removal of a veil occlusion of the upper 4th ventricle aqueduct produced immediate recovery in five of six patients. The conversion of aqueductal stenosis to veil occlusion is postulated as the mechanism of "primary" veil obstruction found in infants. This new clinical entity is more common than realized. We report one patient with compartmental 4th ventricular hydrocephalus.