[A case of infected subdural hematoma complicating chronic subdural hematoma in a healthy adult man].

The authors report a case of so-called "infected subdural hematoma" as a complication of chronic subdural hematoma. The patient was a 55-year-old man who had sustained a small laceration of the forehead in a traffic accident on March 29, 1995. No fractures were detected on skull roentgenograms, and general and neurological examinations failed to reveal any abnormal findings. In early August 1995, the patient began to experience headaches, and on August 5 he developed a fever of 38 degrees C. On August 8 he suffered a left motor seizure and was admitted to our hospital. Laboratory studies revealed a peripheral leukocyte count of 10,800/mm3 and a C-reactive protein level of 18.1 mg/dl. Computed tomography scans showed a thick right fronto-parietal subdural low density mass and a thin left frontal subdural low density mass. An emergency operation was performed via a single right fronto-parietal burr hole. A chronic subdural hematoma containing slightly yellowish, bloody, purulent fluid was found beneath an outer membrane. The hematoma was irrigated with physiological saline containing antibiotics, and a drain was inserted into the subdural space. A subdural membrane was also present on the left but it contained no pus. Aggressive antibiotic therapy was performed, and the patient was discharged without any neurological deficit. Histologically the membrane was determined to be the outer membrane of a typical chronic subdural hematoma. Enterococcus faecalis, which has rarely been reported to cause infection of the central nervous system, was detected in a bacterial culture of the pus. Systemic investigation showed no evidence of otorhinologic or other focal infection. The above clinical findings suggested that hematogenous seeding of a chronic subdural hematoma had occurred in this patient. Subdural empyema arising from hematogenous seeding to a pre-existing subdural hematoma by an infection is very rare, but this type of complication must be kept in mind not only in the elderly, infants, and compromised hosts, but in patients without complications as well.