Stroke or not? Stroke mimics and chameleons: uncommon presentations of a common disorder

Abstract

Background: Up to 30% of suspected stroke presentations will subsequently have a different diagnosis. Two scenarios must be considered: a false positive “mimic”, and a false negative “chameleon”. Also, contemporary brain imaging techniques induce a greater risk of finding “incidentalomas”. The objective of this review is identifying and describing the most frequent clinical situations in which these scenarios are encountered. Material and methods: The relevant terms combination [chameleon OR mimic OR incidentaloma] AND stroke were searched on PubMed database. The following filters were applied: publication date – 5 years, species – humans, age of subjects – 18+, language – English. 320 results were identified, from which only Meta-analyses (1), Reviews (20) and Systematic Reviews (4) were analyzed (total – 25 papers). Results: Stroke can have an unusual presentation and can often not be immediately recognized. Stroke mimics account for up to 25% of admissions for probable strokes, most commonly described including seizures, migrainous aura, venous thrombosis, posterior reversible encephalopathy syndrome and neoplasms. The commonest identified chameleons were: altered mental status, syncope, hypertensive emergency, systemic infection and suspected acute coronary syndrome. The increased use of MRI also leads to incidental findings in suspected stroke patients, such as: meningiomas, cavernomas, and aneurys. Conclusions: Having unusual presentations, stroke can often not be immediately recognized. The problem with chameleons is more serious than with mimics, because patients are not identified in time, and are not properly treated. Physicians should consider the above-mentioned diagnoses for subsequent appropriate management.