Hematoma from arteriovenous malformation producing hydrocephalus and simulating a thalamic tumor. Report of two cases.

Two patients with a history of progressive unilateral neurological symptoms and signs, and evidence of obstructive hydrocephalus from a mass lesion adjacent to the third ventricle as demonstrated by pneumography, were each found to have an intracerebral hematoma secondary to remote hemorrhage from a small vascular malformation. One patient died shortly after surgical exploration and the other after ventriculography. The pathophysiology of hydrocephalus associated with a vascular malformation is discussed and the need for considering a benign cause for obstructive hydrocephalus from a mass deep in the brain substance is emphasized.