A study was conducted on 525 consecutive patients ranging in age from 36 years to 86 years to determine whether diurnal variation occurs in the onset of acute ischemic stroke. There was a clear (D max =0.19, P<0.01) diurnal variation with a significant (t=-4.96, P<0.001) peak between four a.m. and six a.m. Strokes occurred more often during the two hours following awakening than during any other time of the day. The peak time of ischemic stroke in our study was about two hours earlier than in previous reports, probably because of the different waking times of the studied populations. We concluded that the time of awakening influences the circadian distribution rather than the time of day itself. Ann Saudi Med 1994;14(3):201-203. S Torun, G Özdemir, Very Early Morning Increase in Onset of Ischemic Stroke. 1994; 14(3): 201-203 Ischemic vascular events have been reported repeatedly to occur following a circadian rhythm.1-3 Most of these reports deal with myocardial ischemia, 4,5 acute myocardial infarction, 6,7 and sudden cardiac death. 8,9 Similar circadian variation of cerebral ischemia was also reported but with contradictory findings. [10][11][12][13][14][15][16] While there are considerable variations in patient populations and methods, most of the previous studies note a peak onset in the morning hours, [17][18][19] particularly at the time of awakening.
20The aim of the present study was to investigate the possibility that acute ischemic stroke (IS) has a circadian variation and IS occurs more often at certain times of the day in Turkish sufferers whose awakening time is probably different from western populations.
Material and MethodsProspectively collected data on 525 patients with acute IS, admitted to our Department of Neurology between December 1986 and May 1990 were analyzed. Only the cases in which the diagnosis of IS was ascertained by computed tomography (CT), and only strokes of acute onset in which symptoms reached their maximum in less than eight hours and remained present for more than three weeks were considered.The time of onset of symptoms attributed to IS and the time of awakening were obtained from the patient, family members, or other observers.We considered the time of onset to be the hour in which the patient or an observer first became aware of the event. In patients who first noticed their stroke symptoms on waking, it was presumed that the IS had occurred during sleep. Details of whether the patient was active or at rest when the IS occurred were also recorded.The frequency of symptom onset was tabulated for two hourly intervals in the day beginning one minute after the previous hour (i.e., 12:01 a.m. to 2 a.m., 2:01 a.m. to 4 a.m., etc.). The Student's t-test and Kolmogorov-Smirnov type statistics were used for statistical analysis involving comparison of distributions of IS over a 24 hour period.
ResultsOur study included 525 patients with acute IS, consisting of 295 males and 230 females ranging in age from 36 to 86 years (mean age 64.2). There was a clear and significant diur...