CT Imaging Study Identifies Predictors of Subdural Hematoma Expansion
New research published in Emergency Radiology suggests that certain clinical and imaging features from CT scans could help providers better predict the expansion of acute subdural hematomas (SDH), informing more timely and effective treatment strategies.
Subdural hematomas occur when blood collects between the brain and its outer covering, often after trauma. Expansion of these bleeds can increase pressure inside the skull, leading to brain injury, neurological impairment, and potentially death if left untreated. Older adults, particularly those over age 65, face the highest risk due to age-related fragility, increased rates of falls, and frequent use of blood thinners.
“The incidence of subdural hematomas is increasing due to the aging population, frequent use of anticoagulants/antiplatelets, and fall-related trauma. While some acute SDHs remain stable and require no intervention, others expand, necessitating neurosurgical management,” said senior author David Yousem, MD, of Johns Hopkins Medical Institution. “Our study objective was to better identify predictors of acute SDH enlargement to guide clinical management.”
The team conducted a retrospective analysis of more than 32,000 noncontrast head CT scans performed over a six-year period, identifying 262 patients with acute SDH for further evaluation. Researchers reviewed demographic, clinical, and imaging features to determine which factors correlated with hematoma enlargement and the eventual need for surgical intervention.
About 25 percent of the patients experienced SDH growth on follow-up imaging. Several variables were linked to an increased likelihood of expansion, including larger hematoma size at baseline, the presence of concurrent subarachnoid hemorrhage, and a history of hypertension. Additional imaging findings, such as convexity location and midline shift, were also associated with higher risk.
The investigators proposed that an initial hematoma thickness of 8.5 millimeters may serve as a practical threshold for anticipating surgical intervention. Notably, none of the subdural hematomas measuring less than 3 millimeters required surgery, though some still expanded slightly on subsequent imaging.
These results could help clinicians stratify risk more effectively and make evidence-based decisions about when surgical consultation or closer monitoring is warranted. For example, patients presenting with larger bleeds, midline shift, or hypertension might be more closely observed for signs of worsening. Conversely, very small SDHs under 3 mm may rarely need immediate surgical consideration.
The authors cautioned, however, that their work is retrospective and emphasized the need for prospective studies to validate these predictors. In particular, further investigation is needed to clarify outcomes for patients with very small SDHs, since some in this group did show minor expansion even if surgical treatment was not ultimately required.
Overall, the findings offer new insights into the progression of subdural hematomas and highlight the potential for CT-based predictors to guide management decisions. By identifying patients most at risk for expansion, providers may be able to intervene earlier, improve outcomes, and reduce the likelihood of serious complications.