Location‐Specific Analysis of Hematoma Expansion in Intracerebral Hemorrhage

Background Hematoma expansion (HE) is a potential modifier of intracerebral hemorrhage (ICH) outcome, yet reducing HE does not necessarily improve prognosis. This may reflect the complex relationship between location, baseline volume, HE, and outcomes, where different locations have varying hematoma growth and differing impacts on prognosis. Prior HE studies have oversimplified location categorization into lobar and deep. Therefore, we aim to investigate how HE varies across more specific location categorization and examine their interactions. Methods We retrospectively analyzed 691 nonanticoagulated patients with spontaneous ICH from the University of Hong Kong ICH registry (2011–2022) and 3 regional hospitals (2020–2022). Locations were categorized into lobar, putamen/external capsule, globus pallidus/internal capsule, thalamus, cerebellum, and brainstem. HE was defined as a >33% or >6 mL increase in intraparenchymal hematoma. The associations between location and volume with HE were assessed using multivariable logistic regression. Location‐specific volume cutoffs were defined with the receiver operating characteristic curves. Results The HE rates and absolute volume growth differed significantly by location (both P <0.001). The risk of HE also varied across locations ( P =0.016), but only cerebellar ICH showed a significantly lower risk compared with lobar ICH (adjusted odds ratio, 0.313 95% CI, 0.098–0.998). Additionally, there was a significant interaction between baseline volume and location with HE ( P interaction <0.001). HE risk was significantly higher for baseline hematoma volume ≥27.2 mL for lobar (aOR, 8.71 95% CI 3.35–22.64) and≥36.2 mL for putamen/external capsule (adjusted odds ratio, 2.83 95% CI, 1.53–5.25), but not for other location‐specific volumes. Conclusions The risk of HE and its association with baseline volume varied by ICH locations. These findings provide novel insight to guide patient selection for antiexpansion therapies.