Postoperative intracranial haematoma is a serious complication of intracran
ial surgery with a mortality rate of around 30%. There have been reports im
plicating abrupt rises of blood pressure during the last stages or immediat
ely after the procedure, in the production of the clot. This prospective st
udy examined this hypothesis. Over the last 7 years, 526 consecutive patien
ts underwent craniotomy under a strict anaesthesiological protocol based on
deep opioid analgesia which virtually eliminated any acute elevations of t
he arterial pressure during and immediately after craniotomy. Emergence fro
m anaesthesia was delayed for an average of 1 1/2-2 h following the procedu
re. Postoperative CT was obtained in every patient. There have been no case
s of postoperative clot formation in this series of patients. The results o
f the study suggest that postoperative haematoma is probably an avoidable c
omplication of intracranial surgery.