ABSTRACT
PURPOSE: This study aimed to elucidate the severity of neurological deficits in a large series of patients with acute spontaneous spinal epidural haematoma (SSEH) using magnetic resonance imaging (MRI). METHODS: We included 57 patients treated for acute SSEH at 11 institutions and retrospectively analysed their demographic and MRI data upon admission. We investigated MRI findings, such as the haematoma length and canal occupation ratio (COR). The neurological severity of SSEH was assessed based on the American Spinal Injury Association score on admission. RESULTS: Of the 57 patients, 35 (61%) presented with severe paralysis. The MRI analysis showed that SSEH was often located in the cervical spine, dorsal to the spinal cord, and spread over more than three vertebrae. No differences in age, sex, and aetiology were found between patients with and without severe paralysis. The hypo-intensity layer encircling the haematoma, intra-haematoma heterogeneity, and increased CORs were observed more frequently in the severe paralysis group. Furthermore, pathological examination of a dissected haematoma from one patient with a hypo-intensity layer revealed a collagen layer around the haematoma, and patients with intra-haematoma heterogeneity were more likely to have a bleeding predisposition. CONCLUSIONS: In this large series of patients with SSEH, we identified some MRI features associated with severe paralysis, such as the hypo-intensity layer, intra-haematoma heterogeneity, and increased COR. Accordingly, patients with these MRI characteristics should be considered for early surgical intervention.