Hypertrophic anterior falx artery associated with interhemispheric subdural empyema--Case report.

A 14-year-old boy presented with interhemispheric subdural empyema. Angiography demonstrated a hypertrophic anterior falx artery. He was treated with antibiotics and craniotomy to evacuate the lesion. The postoperative course was uneventful with no signs of neurological deficit. The abnormal artery was no longer visualized angiographically after the resolution of the empyema. Reactive appearance of the anterior falx artery is a pathognomonic sign of interhemispheric subdural empyema.