fig 1.

Baseline CT and CT studies obtained during present admission.

A, Baseline noncontrast axial 5-mm section shows hyperdense colloid cyst (arrow) in the rostral aspect of the third ventricle. There is moderate dilatation of the lateral ventricles and cerebral atrophy secondary to AIDS. In this view, the colloid cyst is round in appearance.

B, CT scan obtained immediately after acute neurologic deterioration shows marked hydrocephalus and hypodensity in the white matter of the frontal lobes. The etiology of the presumed punctate hemorrhage in the right frontal lobe is not known.

C, CT obtained immediately after the initial ventriculostomy shows a right-sided catheter that has decompressed the lateral ventricle. The left lateral ventricle remains enlarged and there is mild midline shift to the right. A small amount of blood is present in the right lateral ventricle secondary to catheter insertion.

D, CT done after insertion of left-side ventriculostomy shows decreased hydrocephalus, compared with B, and no midline shift.