Shedding new light on rapidly resolving traumatic acute subdural hematomas.

BACKGROUND: Rapidly resolving acute subdural hematomas (RRASDHs) have been described in case reports and case series but are still poorly understood. We hypothesized that a cohort analysis would confirm previously reported predictors of RRASDH including coagulopathy, additional intracranial hemorrhage, and low-density band on imaging. We also hypothesized that rapid resolution would be associated with improved trauma outcomes. METHODS: We reviewed all nonoperative acute subdural hematomas (ASDHs) treated at our center from 2011 to 2015. Inclusion criteria were ASDH on computed tomography (CT), admission Glasgow coma score >7, and repeat CT to evaluate ASDH change. RRASDH was defined as reduced hematoma thickness by 50% within 72 h. Clinical data, CT findings, and trauma end points were analyzed for the RRASDH and nonresolving groups. RESULTS: There were 154 ASDH patients included, with 29 cases of RRASDH. The RRASDH group had a lower rate of comorbidities than the nonresolving group (58.6% versus 78.4%, P = 0.03) and a lower rate of prehospital anticoagulation (7.7% versus 37.1%, P = 0.004). Previously reported predictors of RRASDH did not differ between the groups, nor did any clinical outcome measures. When compared with patients who experienced rapid growth (>50% increased width in 72 h), the RRASDH group had lower mortality (3.4% versus 23.5%, P = 0.04). CONCLUSIONS: To our knowledge, this is the largest review of RRASDHs. We identified two previously unrecognized factors that may predict resolution; however, previously reported predictors were not associated with resolution. We also found no relationship between RRASDHs and improved standard trauma outcomes, calling into question the clinical significance of RRASDH.