Circadian Variation in the Onset of Acute Cerebral Ischemia: Ethiopathogenetic Correlates in 80 Patients Given Angiography

In a continuous series of 80 acute ischemic hemispheric strokes, the onset of symptoms was between 6:01 a.m. and noon in 45% of cases, between noon and 6:00 p.m. in 22.5%, between 6:Ol p.m. and midnight in 31.25%, and between midnight and 6:00 a.m. in 1.25% (p < 0.0001). By means ofangiography and computerized tomography, and by detection of arterial and cardiac sources of emboli, four stroke subtypes were identified. Embolic and thrombotic strokes had their most frequent onset between 6:01 a.m. and noon (45% and 71%, respectively), whereas strokes of unknown origin and lacunar strokes were randomly distributed between 6:01 p.m. and midnight. The morning activation of the catecholaminergic system can account for this pattern of circadian onset of ischemic stroke.