Prevalence of chameleons in patients with ischemic stroke: A cross-sectional study

Stroke is a leading cause of mortality and disability worldwide, with timely identification being crucial for effective treatment. However, some patients present as "stroke chameleons" (SC) displaying atypical stroke symptoms that mimic other conditions, often leading to delayed diagnosis and poorer outcomes. This study aims to assess the prevalence and clinical characteristics of SC in a comprehensive stroke center in Colombia.

This cross-sectional study involved ischemic stroke patients admitted to a high-level medical center in Bogotá, Colombia, from January 1, 2021, to December 31, 2023. We identified SC, defined as patients with a confirmed acute stroke in whom a stroke was not initially suspected, as indicated by a negative Cincinnati prehospital stroke scale and no activation of the stroke protocol. We evaluated the proportion of SC, their clinical and imaging characteristics, and compared them with non-SC patients.

Among 635 ischemic stroke patients, 78 (12.2%) were identified as SC, while 557 (87.8%) were identified as non-SC. SC exhibited a lower National Institutes of Health stroke scale score and were more likely to present with altered mental status (38% vs. 24%, p = 0.008), dizziness (30% vs. 16%, p = 0.004), and behavioral changes (8% vs. 2%, p = 0.005). SC displayed less middle cerebral artery involvement (24% vs. 56%, p = 0.047) and more multi-territory involvement (34% vs. 17%, p <0.001). In addition, SC had a higher rate of normal computed tomography scans.

SC are a significant subset of ischemic strokes, presenting with atypical symptoms that complicate the diagnosis. Recognizing these non-traditional presentations is essential for timely diagnosis, treatment, and potentially improved outcomes.