Subdural empyema--continuing diagnostic problems in the CT scan era.

Fourteen cases of subdural empyema seen in Oxford since the introduction of the CT scanner are reviewed; 11 were male and 12 survived. The clinical presentation was stereotyped and characterised by severe headache, fever and meningism followed after a few days by rapidly progressive drowsiness, focal signs, papilloedema and seizures. All had radiological evidence of paranasal sinus disease (particularly frontal) although this was not apparent clinically in the majority. Plain skull and sinus radiographs remain important early investigations. Over-reliance can be placed on the CT scan which initially may be normal or show only non-specific hemisphere swelling. Parafalcine collections are easily missed. The diagnosis of subdural empyema remains difficult and a high index of clinical suspicion is required. Outcome depends on prompt treatment with parenteral antibiotics and surgical drainage.