Heterogeneity of acute subdural collections: In search of a unifying feature

Abstract

Introduction A variety of different acute subdural hematoma patterns of density have been reported in the literature and are commonly seen in clinical practice, including rare hypodense acute subdural hematomas. It is unclear if these acute hypodense collections are entirely hypodense or if on close inspection, they can reveal subtle, tiny hyperdense components. The purpose of this study was to determine if all acute subdural hemtomas contain a hyperdense component, including seemingly entirely hypodense subdural collections. Methods Non-contrast CT scans of 111 patients containing 320 hyperacute or acute subdural collections were analyzed for the presence of a hyperdense component. Hounsfield measurements were recorded. Results All hyperacute and acute subdural hematomas in our study had a hyperdense component. Hyperacute subdural hematomas have a hyperdense component >97.5% of the time (95% confidence), and acute subdural hematomas have a hyperdense component >99% of the time (95% confidence). Conclusion Lack of a hyperdense component in a subdural hematoma makes acute or hyperacute hematoma highly unlikely, and alternative diagnoses should be considered.