Perimesencephalic hemorrhage

TLDR

The cause of this benign disorder remains elusive, but a venous or capillary source seems likely. The study examined 28 patients with subarachnoid hemorrhage who had normal angiograms. Early CT revealed that perimesencephalic hemorrhage is confined to cisterns around the midbrain, occurs in only 1 of 92 aneurysmal cases, is not associated with intracerebral or intraventricular bleeding, and patients typically recover fully within three months.

Abstract

We studied 28 patients with subarachnoid hemorrhage and normal angiograms. On early CT (within 5 days) in 13 cases, blood was seen mainly or only in the cisterns around the midbrain. This pattern of hemorrhage was found in only 1 of 92 patients with a ruptured aneurysm. None of the unexplained perimesencephalic hemorrhages was associated with intracerebral hematoma or intraventricular hemorrhage. The clinical features also differed from those of aneurysmal hemorrhage; loss of consciousness was rare, and after 3 months, all 13 patients had returned to normal life. The cause of this benign disorder remains elusive, but a venous or capillary source seems likely.