A Helpful Tool in Diagnosing Stroke Mimics: Arterial Spin Labeled Perfusion Magnetic Resonance Imaging

Prompt and effective management of acute ischemic stroke in the emergency setting requires a high level of suspicion and accurate diagnosis. Conversely, identifying stroke mimics can be challenging, given the similarity of their clinical symptomatology, the necessary rapid assessment and triage, and the overall frenetic pace inherent in the goal of rapid thrombolysis ("time is brain").

We describe a case that involves an elderly patient with acute hemiplegia and dysarthria. Given these concerning symptoms, and multiple preexisting cerebrovascular risk factors (including paroxysmal atrial fibrillation), a "stroke alert" was issued. Imaging was negative for infarct and she was ultimately diagnosed with hemiplegic migraine based on her symptoms and impressive findings on a novel magnetic resonance sequence called arterial spin labeled (ASL) perfusion. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Identifying a nonischemic etiology in a presumed stroke patient, while often difficult, can obviate unnecessary treatment, improve patient care, and promote appropriate resource allocation. As imaging and treatment of cerebrovascular disease advances, the optimization of multidisciplinary care should incorporate neuroradiologists informing and availing their clinical colleagues of applications of an ever-expanding imaging armamentarium. This case is an excellent example of both a common challenging stroke mimic and the potential benefits of ASL perfusion imaging in refining and expediting accurate diagnosis. In addition, it serves as a more general introduction to the particular strengths of this noninvasive, noncontrast magnetic resonance technique, which can be employed to assess varied emergent neuropathology.