Circadian variability in hemorrhagic stroke

The time of occurrence of intracerebral hemorrhage shows a biphasic circadian pattern characterized by a prevalent peak in the morning, similar to that reported for other hemorrhagic events such as subarachnoid hemorrhage, rupture of aortic aneurysms, and epistaxis. Hypertension is considered to be one of the most important predisposing factors for intracerebral hemorrhage. However, hypertensive and normotensive patients showed the same pattern, which closely resembles the physiological circadian rhythm of blood pressure. These data suggest that blood pressure variations (irrespective of the degree of hypertension) may be crucial in determining the rupture of a critically weakened arterial wall.