Influence of head position on the prognosis of experimental subarachnoid hemorrhage.

Autogenous blood was injected repeatedly into the intracranial subarachnoid space of cats, the heads of which were placed in one of four positions (prone, supine, left side down, and right side down). Epidural pressures, mean aortic blood pressures, and pulse rates were measured, and their responses to the repeated injections were analyzed. The distribution of the injected blood was different among the four groups. The cats in the sulpine position had the greatest amounts of blood in the posterior fossa and tolerated the injections least well. The position of the head at the time of a subarachnoid hemorrhage may influence the prognosis; positions that favor accumulations of blood around the brain stem carry the greatest risk.