Bleeding in the brain: Killer waves of depolarization in subarachnoid bleed

Hemorrhages in the brain are responsible for about 15% of strokes and are particularly difficult to treat. Costantino Iadecola assesses a new clinical study that may change the view of why a common form of hemorrhage, subarachnoid hemorrhage, often leads to death. Massive brain lesions often develop days after the initial event, a dangerous complication previously attributed to vasospasm, narrowing of the arteries. The study suggests that these lesions may instead by caused by neuronal depolarization, extending in waves across the brain. Gregory del Zoppo explores the connection between deposition of toxic amyloid-β peptides in the brain and hemorrhage. He discusses studies suggesting that the peptides inactivate proteins in the blood that can stop hemorrhage.