Clinically presenting acute/subacute ischemic stroke: Differential diagnosis of the non-enhanced CT hypodensity by advanced neuroimaging

Objectives: Patients presenting to the emergency room with an acute or subacute onset of focal neurological deficits are evaluated initially by non-contrast computed tomogram (CT) of the brain. This is primarily carried out to differentiate an ischemic from hemorrhagic stroke. However, other neurological conditions may have a similar clinical presentation as well as only hypodensities on CT scan, thus mimicking ischemic stroke. This review focuses on the advanced neuroimaging modalities that help differentiate these other conditions from a cerebral infarction. Methods: The literature was reviewed in order to ascertain what conditions would clinically and by CT mimic an acute/subacute ischemic infarction, and what advanced neuroimaging techniques would be most useful in differentiating these conditions. Results: Several infectious, inflammatory, metabolic and vascular diseases were found with clinical presentations identical to subacute/acute ischemic cerebral infarction, which also could demonstrate only hypodensities on a non-enhanced CT scan. However, advanced neuroimaging techniques could readily differentiate these conditions from ischemic infarction. Conclusions: As presented in this review, although several diseases initially present a diagnostic dilemma upon presentation because of their clinical and non-enhanced CT similarities to cerebral infarction, advanced diagnostic neuroimaging readily establishes their unique pathologies.