Response to Letter Regarding Article, “Safety of Thrombolysis in Stroke Mimics: Results From a Multicenter Cohort Study”
We would like to thank Dr Radecki for his valuable comments on our study. Quite rightly, he emphasizes the complexity of the definition of a true stroke mimic and questions whether our reported rate of 1.8% is rather an underestimation.1 The reason for our relatively low rate is 2-fold. First, our cohort was collected in experienced stroke centers only, probably leading to a somewhat lower rate. Second, to be able to obtain a reliable estimate of the intracranial hemorrhage rate after intravenous thrombolysis in definite stroke mimics, the primary aim of our study, on purpose we used a rather strict definition largely after the criteria of Hand et al,2 requiring another convincing explanation for the symptoms.
Indeed, there remains a gray area in which doubt about the final diagnosis persists even after extensive investigations. Whether patients in whom diffusion-weighted imaging (DWI) does not reveal any abnormalities after intravenous thrombolysis should be classified as stroke mimic or as transient ischemic attack depends on the purpose of the study. In turn, even patients with stroke mimics (eg, seizures) can show hyperintense lesions on DWI. Thus, it can be misleading to base the distinction between acute ischemia and a stroke/transient ischemic attack mimic solely on the presence versus absence of acute DWI lesions.
We performed a pragmatic study reflecting daily clinical practice with a focus on the acute phase, in which the physician has to decide whether a patient should receive intravenous thrombolysis or not based on information available at that very moment. We completely agree with Dr Radecki that to, in detail, investigate the uncertain group DWI in all consecutive patients, probably still in a research setting so far, will largely help in a more precise estimate of the true stroke mimic rate and contribute to consensus about the definition of a stroke mimic. We hypothesize, however, that the complication rate will not or only slightly increase by broadening our domain of stroke mimics with DWI-negative patients, because of a expected slightly higher complication rate in patients with ischemia (ie, definite transient ischemic attack or stroke).
We have hopefully been enough careful with our clinical recommendations. We state in our discussion that in our opinion, although efforts should be made to avoid intravenous thrombolysis in such patients, rapid treatment is likely more beneficial than adding extensive exams to rule out mimics in daily clinical practice. It is important to stress that our current findings are restricted to experienced stroke centers. Future research with magnetic resonance imaging in all consecutive stroke patients will certainly learn us more about this complex category of patients.
Paul J. Nederkoorn, MD, PhD
Sanne M. Zinkstok, MD
Department of Neurology
Academic Medical Center University of Amsterdam
Amsterdam, the Netherlands
Stefan T. Engelter, MD, PhD
Neurological Clinic and Stroke Unit
University Hospital Basel
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- © 2013 American Heart Association, Inc.
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