Wake-Up to Wake-Up Stroke!

Abstract

here is a typical story. a patient arrives at the emergency room. he was well when he went to bed and then he woke up with symptoms suggestive of stroke several hours later. even without further scrutiny, the clinician determines that intravenous thrombolytic therapy is contraindicated. end of story. Such is the plight of patients with wake-up stroke. Can we do more? Can we do better? Wake-up stroke is not rare. about 5 to 30% of patients who presents to the emergency room for presumed acute stroke have wake-up stroke. Because of uncertainty regarding the time of symptoms onset, these patients are routinely excluded from intravenous thrombolytic therapy. in a population-based study, 14% of ischemic strokes presented to an emergency department were wake-up stroke. among these patients, more than one third would have been eligible for thrombolysis if arrival time were not a factor. 1 if the same pattern holds true for Canada, that would translate to thousands of additional patients eligible for thrombolytic therapy. When one deals with wake-up stroke, one needs to re-visit the concept of "last seen well". the time "last seen well" is a good and objective way to time the onset of stroke symptoms. When symptom onset is unwitnessed, such as patients who are aphasic and alone at the time, "last seen well" may become an obstacle to thrombolysis. in the case of wake-up stroke, "last seen well" often puts the patient outside the conventional therapeutic time window. although well-intentioned, we may not be right to assume that the time of symptom onset is close to the time of "last seen well". let us assume that the onset of stroke symptoms occurs in a random fashion during sleep hours. for a patient who was well when he went to bed eight hours earlier, the chances of stroke occurring during the final four hours will be the same as the chance of it starting during the first four hours, or 50%. that means that 50% of these patients are potential candidates for intravenous thrombolytic therapy. of course, the assumption that the chance of stroke occurring equally at every time point during sleep is questionable at best. other vascular events, particularly acute myocardial infarction in which the onset is marked by the development of chest pain, tend to occur in the final hour before arousal. ischemic strokes likely follow the same diurnal pattern. 2 Several studies compared the clinical and radiological features between patients with wake-up stroke and patients with strokes that occurred within the therapeutic windows of alteplase. the two groups of patients were essentially identical in these studies. 3,4 the evidence suggests that wake-up strokes more likely occur in the early morning hours just before arousal. Clinicians involved in thrombolytic therapy for acute stroke know that some patients presenting within 4.5 hours of symptoms onset will show well defined infarct on cranial computed tomogram (Ct) scan. We also have examples of patients who have normal cranial Ct scan even though their symptoms occurred more than 4....