Clinical investigation of chronic subdural hematoma with impending brain herniation on arrival.

Chronic subdural hematoma (CSDH) with brain herniation signs is rarely seen in the emergent department. As such, there are few cumulative data to analyze such cases. In this study, we evaluated the clinical features, risk factors, and rates of completion with impending brain herniation on arrival in a cohort study. We analyzed 492 consecutive patients with CSDH between January 2010 and October 2015. First, we analyzed the clinical factors and compared them between patients with or without brain herniation signs on admission. Second, we compared clinical factors between patients with or without completion of brain herniation after operation among patients who had brain herniation signs on arrival. Eleven (2.2%) patients showed brain herniation signs on arrival, and six patients (1.2%) progressed to complete brain herniation. Patients with brain herniation signs on arrival were significantly older (P = 0.03) and more frequently hospitalized with a concomitant illness (P < 0.0001). Niveau formation (P = 0.0005) and acute-on CSDH (P = 0.0001) on computed tomography were also more frequently seen in patients with brain herniation signs. Multivariate logistic regression analysis showed that age older than 75 years (OR 2.16, P < 0.0001), niveau formation (OR 3.09, P < 0.0001), acute-on CSDH (OR 14, P < 0.0001), and admitted to another hospital (OR 52.6, P < 0.0001) were independent risk factors for having had brain herniation signs on arrival. On the other hand, having a history of head injury (P = 0.02) and disappearance of the ambient cistern (P = 0.0009) were significantly associated with completion of brain herniation. The prognosis was generally poor if the patient had presented with brain herniation signs on admission. Our results demonstrate that the diagnosis is often made late, despite hospitalization for a concomitant illness. When the elderly show mild disturbance of consciousness, physicians except neurosurgeons need to consider the possibility of CSDH regardless of a recent history of head injury.