CIRCADIAN VARIATION IN ACUTE ISCHEMIC STROKE - A HOSPITAL-BASED STUDY

Background and Purpose-We investigated circadian rhythm in ischemic st roke onset and its subtypes, differentiating between first-ever stroke and recurrent stroke. Methods-A consecutive series of 1223 patients w ith ischemic stroke was admitted at 2 reference hospitals; the time of onset of symptoms was obtained, differentiating between onset while a sleep and awake. We compared circadian rhythm between stroke types and between first-ever and recurrent stroke. Results-The onset time was k nown in 914 patients; 25.6% experienced onset on awakening [higher inc idence in thrombotic and lacunar stroke (28.9% and 28.4%, respectively ) than in embolic stroke (18.8%)]. For all stroke subtypes, there was a significant diurnal variation, with a morning peak between 6 AM and noon; after redistributing the hour of onset of patients awakening wit h stroke, the morning peak was minimal in all types of stroke. There w ere no differences in circadian rhythm between patients with first-eve r and recurrent stroke. Conclusions-Only hospitalized patients were st udied. There is a circadian rhythm in all types of stroke, with higher frequency during the day and lower frequency in the last hours in the evening. The highest incidence in the early hours of the morning can be overestimated, due to patients who awaken with stroke. There is no difference in circadian rhythm between first-ever stroke and recurrent stroke.