Significance of pathognomonic features of normal-pressure hydrocephalus on computerized tomography.

In some patients with congenital or acquired hydrocephalus, a low-density area is seen around the lateral ventricle on computerized tomography. Above all, in patients with normal-pressure hydrocephalus following subarachnoid hemorrhage, there appears a specific low-density area which is fan-shaped and irregular and which extends from the bilateral anterior horns to the frontal pole. This disappears or decreases with a VP shunt. Improvement of clinical symptoms is proportional to the degree of disappearance of the low-density area. The essential part of the occurrence of symptoms in patients with normal-pressure hydrocephalus depends upon a low-density area on CT.