Delayed development of extradural haematomas.

Two cases of extradural haematoma of delayed onset, demonstrated by serial computed tomography (CT), are presented. the first patient developed a fatal posterior fossa haematoma, which was not present on the initial CT four hours after the accident. The second patient developed a right parietal haematoma, which was not present on the CT two and a half hours after the accident. These cases are in disagreement with the hypothesis that extradural haematomas reach near maximum size within minutes after trauma.