When you’re called about a patient with new dysarthria, weakness, or altered mental status, stroke is one of the first and most dangerous things that probably comes to mind. Stroke, whether ischemic or hemorrhagic, can present in a variety of different ways depending on the particular insult–anything from tingling in a few fingers to full-on obtundation.
There are quite a few things that mimic stroke (see below), but you should always assume that an acute neurological deficit might be stroke unless there is a very convincing alternative explanation. Stroke is a clinical diagnosis, which means that you do NOT absolutely need brain imaging to prove it. In this “brain attack” study from Scotland, published in 2006, features associated with true strokes were: patient was well within the last week, an exact time of onset can be stated, obvious focal deficit is present, NIHSS score >10 (although some mimics did have high NIHSS scores as well). On the other hand, stroke was less likely in patients with a history of cognitive disturbance, loss of consciousness at onset of episode, witnessed seizure, lack of lateralizing deficits, and who were still able to walk. This study was observational and did have significant limitations–for example, not all patients got imaging and there was no gold standard defined for diagnosis of stroke–but these features square with what I’ve been taught.
- TIA (although many high-risk TIAs are later found to be strokes)
- Stroke recrusdescence (stroke-like symptoms in a patient with a history of stroke triggered by an acute cause)
- Dementia or delirium (including toxic-metabolic encephalopathy)
- Space-occupying lesion (infection, tumor)
- Vestibular dysfunction
- Spinal cord lesion
- Peripheral mononeuropathy
What if you suspect that your patient might actually have a stroke mimic, but you can’t get imaging in time (<3 hours) and they have concerning neurological symptoms and a high NIHSS? Should you withhold tPA? This meta-analysis from Greece suggests that patients who have a stroke mimic also have a lower risk of bleeding from tPA, so if there is any concern about an ischemic stroke, this study recommends giving tPA.