Entrapment of the temporal horn: a form of focal obstructive hydrocephalus.

Three cases of a form of focal hydrocephalus are described which the authors term "entrapment of the temporal horn". Obstruction of one lateral ventricle in the region of the trigone isolates the temporal horn. Continued secretion of cerebrospinal fluid within the temporal horn causes it to behave as a mass lesion. In the cases described the causes of the condition were recurrent glioma, previous tuberculous meningitis and surgical excision of an arteriovenous malformation which extended into the trigone. Shunting of the trapped temporal horn provides satisfactory treatment.