What, may you ask, is a stroke mimic? A stroke mimic is defined as a disease or condition that presents with a stroke-like clinical picture but without neurologic tissue infarction. Several clinical syndromes (listed below) can present with symptoms or signs that resemble an acute ischemic stroke. These mimics include processes that can occur within and outside the central nervous system (CNS). Distinguishing these non-cerebrovascular stroke mimics from stroke is increasingly important in this era of interventional stroke therapies with potential adverse effects.
Why should we be worried about stroke mimics? There are 2 reasons for concern. First, studies indicate that misdiagnosis of stroke — in other words, cases inappropriately labeled as stroke — ranges from 5% to 31% of patients; this can potentially lead to unnecessary and harmful treatments. One study reported a stroke mimic rate of almost 25%, while another study had a mimic rate of 17%, nearly all of whom received tPA.
The second reason to be concerned about mimics is that a significant number of these misdiagnosed patients are mistakenly treated with interventional stroke therapies such as a thrombolytic agent. The rate of treatment of stroke mimics with IV tPA ranges from 1.4% to 16.7%; these rates vary due to different definitions and diagnoses of stroke and stroke mimic. The vital question for the acute care physician is whether thrombolytics are harmful in the patient with a stroke mimic. The risk of symptomatic intracranial hemorrhage remains a real and potentially dangerous complication of IV tPA. A large study showed symptomatic intracranial hemorrhage rates of up to 1.0% in mimics treated with IV tPA. Although this is less than the approximate 6% hemorrhage rate in stroke patients receiving thrombolytics, it remains a significant and possibly avoidable cause of morbidity and mortality.
The diagnosis of stroke is not always straightforward. Differentiation between a stroke and a stroke mimic is difficult due to the wide variety of overlapping clinical presentations. The presence of historical risk factors for cerebrovascular disease and the abrupt onset of symptoms may be the best clues available to the acute care physician to make this distinction.
Stroke mimics can be difficult to differentiate from an actual stroke; they make up 5% to 30% of cases initially diagnosed as a stroke. Stroke mimics treated with IV tPA have a 0.5% to 1.0% risk of symptomatic intracranial hemorrhage. The entire clinical picture, including history, physical exam, labs, and imaging must be taken into account when considering stroke vs. mimic. A review of the research and case presentations will help practitioners with 2 critical actions: differentiate a stroke mimic from an actual stroke, and provide the safest patient care.
This topic is covered more extensively in the following audio course available with CME: