Infected acute subdural hematoma associated with invasive pneumococcal disease

A previously healthy 68-year-old woman presented with a rare case of subdural empyema which developed at the site of preceding acute subdural hematoma (SDH). She was first admitted for treatment of an acute SDH after a fall. Since she was neurologically intact and the SDH volume decreased with conservative management, she was discharged 9 days after admission for follow up as an outpatient. Three days after discharge, she unexpectedly returned with worsening headache and altered mental status. Brain computed tomography (CT) showed increased SDH volume. Her condition deteriorated rapidly after presentation, with further increase in SDH volume. Copious pus in addition to the SDH was evacuated by emergency drainage, establishing the diagnosis of subdural empyema. Streptococcus pneumoniae was identified from bacterial cultures. Despite improvement in postoperative CT findings, she fell into septic shock and died 3 days after the drainage. Autopsy revealed meningitis and lobar pneumonia, and the postmortem diagnosis was invasive pneumococcal disease. Infection of acute SDH resulting in subdural empyema by S. pneumoniae is extremely rare. However, invasive pneumococcal disease is not uncommon in the elderly and tends to cause intracranial bleeding. Considering the high mortality rate of invasive pneumococcal disease and the low vaccination rate among the elderly in Japan, neurosurgeons should ask about the pneumococcal vaccination status.