[Subdural Empyema Caused by Propionibacterium Acnes after Burr-Hole Surgery of Chronic Subdural Hematoma:A Case Report].

A 63-year old man with fever, headache, aphasia, and right hemiparesis was admitted to our hospital one month after the initial burr-hole surgery for left chronic subdural hematoma. Computed tomography(CT)revealed no regrowth of residual subdural hematoma. However, on the basis of the findings from magnetic resonance imaging(MRI)with diffusion-weighted images(DWI), an infection due to residual subdural hematoma was suspected. A small craniotomy was performed, and a little fluid with pus was aspirated from the subdural space. Postoperative antibiotic therapy for subdural empyema was performed, and subsequent culture of pus revealed Propionibacterium acnes ( P. acnes ). The patient's symptoms resolved, and he returned to work two months later. Subdural empyema caused by P. acnes after burr-hole surgery for chronic subdural hematoma is rare. We should consider infection due to residual hematoma in patients with recurrent symptoms and signs of inflammation, even in the absence of apparent regrowth of residual hematoma after burr-hole surgery.