Pathogenesis of Spinal Subdural Hematoma Based on Histopathological Findings: A Case Report.

Spinal subdural hematoma is a rare condition whereas intracranial chronic subdural hematoma is well-recognized and documented in clinical settings. Despite various theories that have been proposed, the exact pathogenesis of spinal subdural hematoma remains to be elucidated. Herein, we report a rare case of spinal subdural hematoma with a co-existing intracranial chronic subdural hematoma and deduce its etiology using histopathological findings. A 76-year-old Japanese man with slight hemiparesis due to intracranial chronic subdural hematoma underwent burr hole surgery with successful drainage of the hematoma. The patient could not walk unassisted after the surgery. Spinal magnetic resonance imaging was performed, revealing a subdural hematoma extending from the T11 to S2 levels. The patient subsequently underwent the evacuation of spinal subdural hematoma 12 days after initial surgery. Intraoperatively, we identified a dark liquefied hematoma with capsule formation. Histological examination of the resected capsule revealed loose fibrovascular tissues comprising capillaries, collagen fibers, a small number of macrophages, and hemosiderin deposits. These findings were very similar to the pathology of intracranial chronic subdural hematoma so the pathogenesis of spinal subdural hematoma in this case was considered identical to that of subacute or chronic subdural hematoma. The patient was transferred to a rehabilitation hospital, and 4 months after the lumbar surgery, no recurrence was observed in the magnetic resonance imaging examination. Subacute or chronic spinal subdural hematoma may result from various pathogeneses that clinicians should consider for correct diagnosis and appropriate management. Our case provides important insights into the pathogenesis of subacute or chronic spinal subdural hematoma.