Clinical Question: Acute or Mimic Stroke?

00:00 When we're evaluating these patients clinically, the first step is to rule out a stroke mimic and rule in a ischemic stroke. And as we said, strokes are diagnosed clinically and so ruling out mimics is done with a good history and comprehensive exam. So the first step in evaluating someone in the emergency department for intervention for an acute stroke is to evaluate for a mimic. When we're looking to determine is it a stroke, there are 4 things we tell patients to think about. And we ask them to act F.A.S.T; to think about F facial droop, A arm weakness, S speech difficulty, and T to know that time is urgent. Clinically, we look comprehensively at the neurologic exam and not just at arm weakness but leg weakness, not just at speech difficulty, but differentiating aphasia and dysarthria. But for patients, what is critically important is presenting to the emergency department as soon as possible.

01:03 So we ask them to act F.A.S.T. and recognize face droop, arm weakness, speech difficulty, and that time is urgent in managing these symptoms. Any patient suffering one of these symptoms should present to the emergency department as soon as possible. When we're thinking about mimics of stroke, is it a stroke or is it a mimic, we can think through some of the common stroke mimics and differential diagnostic considerations. Patients who suffered a seizure can be weak after their focal seizure, we call that Todd's paralysis, that can look like a hemiparesis from a stroke. Hypoglycemia as well as hyperglycemia can cause neurologic dysfunction including focal findings, which is different from other electrolyte abnormalities and so hypoglycemia is an important consideration and differential diagnosis.

01:54 Migraine often presents just with head pain or headache, but complicated migraines can present with neurologic dysfunction. And conditions like familial hemiplegic migraine can present with frank hemiplegia which can very much mimic a stroke. Hypertensive encephalopathy can cause confusion and sometimes focal neurologic deficits. Patients can have reactivation of prior deficits, mass lesions, subarachnoid hemorrhage, peripheral vestibulopathy can look like a brainstem stroke, and even conversion reaction can mimic a stroke. So there are a number of considerations that we need to evaluate for these patients.

02:32 When thinking through some of the more common stroke mimics, let's walk through some of those that we would consider and evaluate in the emergency department. The first is seizure. It's critical to rule out seizure and rule in a ischemic stroke. After a seizure in the postictal process, patients may be weak, there may be focal deficits, there may be motor deficits or non-motor deficits. Those motor deficits we call a Todd's paralysis, but we can see aphasia or sensory loss or any type of focal deficit after a focal onset seizure. We expect spontaneous resolution to occur over hours. And importantly, this is where we're looking for a bystander for the patient or caregiver to evaluate for any signs that would be suggestive of seizure. The second thing we consider is hypoglycemia. Hypoglycemia can present with focal neurologic deficits, aphasia, hemiplegia, any number of focal deficits can be present as well as varying degrees of drowsiness, sedation, or obtundation. This can be assessed in the field. Most patients presenting to the emergency department will already have their blood glucose checked. Blood sugars of less than 70 are considered abnormal and less than 45 we can see neurologic deficits or sometimes anywhere in there. We think about early intervention with IV glucose for resolution of the patient's symptoms. It's important to rule out metabolic encephalopathy. Things like hyperglycemia, hyponatremia, hepatic encephalopathy, other causes of altered mental status can present with varying degrees of sedation, inattention, disorientation, nausea or vomiting that can mimic a posterior fossa or posterior circulation stroke, and so this should be considered and evaluated either en route to the emergency department or in the ER. And then there are 3 other non-emergent conditions that we really would want to rule out for patients presenting with an acute stroke where we're considering intervention. The first is complicated migraine. Again, migraine typically occurs without focal neurologic deficits, but in some cases we see migraine that's complicated with a focal neurologic deficit. That's a diagnosis of exclusion and by clinical basis alone, sometimes we cannot differentiate complicated migraine from ischemic stroke.

04:48 As long as there are no other contraindications to intervention, we would consider intervening to resolve that symptom. And ultimately, if imaging and additional work-up rules out stroke, then we would consider that in future evaluations. A second consideration is conversion reaction. Again, this is a diagnosis of exclusion. We look for comorbid psychiatric diagnosis from that various medications that may have been started or withdrawn that could have precipitated a conversion reaction. But ultimately, it can be very difficult in the ER to differentiate conversion reaction in some settings with a ischemic stroke. And so again, if there are no other contraindications, we may consider acute intervention for patients who may be suffering from an ischemic stroke but is ultimately diagnosed with conversion. And then the last thing that we would consider is reactivation of prior deficits. This is really important. Patients who have had a stroke can have another stroke. At the same time, fever, electrolyte dysfunction, new medications, or any other physical, psychosocial, or emotional stressors can cause re-exacerbation or recurrence of old stroke symptoms.

05:58 What's critical in evaluating these patients is determining whether the current symptoms are the same as the old stroke symptoms. If someone's had a prior left MCA stroke in the setting of fever or infection or other exacerbation, they may look like they're having their old left MCA stroke again. They may have recovered and we see those same symptoms as a result of the fever or the stressor. That patient should not have symptoms of a right MCA stroke or a PCA stroke or some other territory of involvement. And so when evaluating these patients, we want to understand what were the symptoms after the first stroke and are those the same as what we're seeing now. And these important mimics are evaluated in the emergency department at the time that the patient presents to rule out things that aren't stroke and rule in a patient who is a candidate for acute intervention.