The other major cause of hemorrhage is rupture of the walls of the small penetrating arteries serving deep structures, with bleeding directly into the brain and its ventricles (intracerebral hemorrhage).  These vessels are at particular risk because of their thin muscular walls and narrow lumens.  It is thought that the cumulative effects of untreated hypertension and atherosclerosis or other kinds of pathologic changes weaken their walls and put them at special risk for rupture.


This is a microscopic section of a small artery that penetrates into putamen (one of the basal ganglia located deep in the hemisphere).  Can you see how the normal architecture of the wall has been changed?   Its thickness is uneven, and there are degenerative changes due to hypertension.  This vessel is at risk for rupture.

When a small artery with pathologic changes like those you just saw ruptures, this is the result.  Notice how much of the brain is affected, including its ventricles.


Small penetrating arteries that supply medial structures in the pons are also sensitive to hypertension.  This 45 year-old woman's high blood pressure was treated only sporadically. Can you find the hemorrhage?

Because of the force of arterial blood pressure, a ruptured artery can shoot blood for long distances through the brain.  Furthermore, an increase in the overall intracranial pressure due to the sudden addition of hemorrhaging blood can compress and distort brain tissue located at some distance from the site of arterial rupture.  For these reasons, the neurologic deficits produced by hemorrhagic strokes can reflect damage to regions of the brain remote from the leaking artery.