A systematic review of these data was therefore undertaken to consider whether there was a period during the 24 hours of the day when stroke onset was more likely, to estimate the level of excess risk, and to determine whether this period of increased risk was different for various subtypes of stroke (ischemic, hemorrhagic, or transient ischemic attack).Ī MEDLINE search of publications in all languages from 1966 to December 1997 was performed with both text word searching and the appropriate MESH headings of “circadian variation,” and “stroke, cerebrovascular accident, transient ischemic attack, or brain attack.” The bibliographies of each of the retrieved publications that contained primary data about the timing of the onset of stroke were reviewed, and relevant citations in these listings were also evaluated for inclusion in the meta-analysis. More recently, data have been reported from many different countries regarding both timing of the onset of acute stroke and the subtype of stroke. 6 7 8 This led to the conclusion that especially because acute therapies for stroke-in-evolution were not particularly effective, there was little reason to consider acute stroke as a medical emergency because the onset of symptoms was thought to occur during sleep, when most patients would not recognize them. 2 3 4 5Įarly studies of the timing of acute stroke, however, indicated that many afflicted patients reported awakening with new neurologic deficits, and several reports indicated that acute strokes tended to occur either during the evening hours or during sleep. 1 Some believe this morning excess of cardiovascular risk parallels the usual circadian pattern of physical activity, blood pressure, plasma catecholamines, and/or plasma cortisol. 1 A similar meta-analysis of 19 studies involving 19 390 sudden cardiac deaths indicated a 29% increase in risk for this 6 am to noon time period. A recent meta-analysis of the 30 reports from across the world, which included 66 635 acute myocardial infarctions, has demonstrated a 40% excess risk between 6 am and noon compared with the rest of the day. Several types of cardiovascular events, including acute myocardial infarction and sudden cardiac death, display significant circadian variation in the timing of onset of symptoms. All three subtypes of stroke had a significantly higher risk between 6 am and noon (55% for 8250 ischemic strokes 34% for 1801 hemorrhagic strokes, and 50% for 405 transient ischemic attacks).Ĭonclusions-These data support the presence of a circadian pattern in the onset of stroke, with a significantly higher risk in the morning.
There were 29% fewer strokes between midnight and 6 am, a 35% decrease compared with the other 18 hours of the day. There was a 49% increase (95% confidence interval, 44% to 55%) in stroke of all types between 6 am and noon (compared with expectations if no circadian variation was present), which is a 79% (95% confidence interval, 72% to 87%) increase over the normalized risk of the other 18 hours of the day. Results-All subtypes of strokes displayed a significant ( P<0.001) circadian variation in time of onset, whether divided into 3-, 4-, or 6-hour time periods. When precise timing was not given, strokes were distributed evenly (that is, biasing toward the null hypothesis of lack of circadian variation). Methods-A meta-analysis of 31 publications reporting the circadian timing of 11 816 strokes was performed, subdividing (when possible) by the type of stroke, according to the time of onset of symptoms. Some reports suggest that stroke does not follow such a circadian variation and that hemorrhagic stroke occurs more often during the evening. Customer Service and Ordering Informationīackground and Purpose-Acute myocardial infarction and sudden death display a circadian rhythm, with a higher risk between 6 am and noon.Stroke: Vascular and Interventional Neurology.
Circ: Cardiovascular Quality & Outcomes.Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB).
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