The position of the patient during neurosurgical procedures on the posterior fossa.

Different parameters were measured on patients in six different positions during infratentorial surgery. One group of data served to prove that such patients were in a steady-state as far as their cardiovascular and ventilatory function was concerned. The other measured parameters concerned the intracranial pressure, the intracranial venous pressure and the cerebral perfusion pressure. It appeared from the comparison of these data, that the lateral sitting (45 degrees) position had important advantages and that in this position the possibility of unfavourable features (such as air-embolism) was minimized.