The significance of periventricular lucency on computed tomography: experimental study with canine hydrocephalus.

In order to investigate the pathogenesis of periventricular lucency (PVL) in hydrocephalus, CT scans were performed with monitoring of the epidural pressure in a series of dogs with hydrocephalus induced with kaolin. PVL of various degrees was detected in the experimental animals, which disappeared immediately after a shunting operation. Correlations have been attempted between PVL on CT scans and histological examinations, contrast enhancement studies, metrizamide ventriculography, and measurement of regional cerebral blood flow in the periventricular white matter. PVL in hydrocephalus is considered to represent acute edema or chronic CSF retention in the periventricular white matter caused by an increase of water content. In other words, it is regarded as a sign of existing or preceding intraventricular hypertension on CT scan, and seems to be a reversible phenomenon to some extent. PVL may therefore became an indication for a shunt.