Elevated intracranial pressure or subarachnoid blood responsible for reduction in cerebral blood flow after SAH

Background. The pathogenesis of cerebral ischemia after subarachnoid hemorrhage (SAH) still remains elusive. The purpose of the present study was to examine whether it is the change in intracranial pressure (ICP) or the extravasated blood that is responsible for cerebral ischemia and cerebral vasoconstriction observed following SAH. Method. Three groups of animals were studied; (1) cisternal injection of 250 mu l blood (SAH), (2) injection of 250 mu l NaCl (saline) or (3) same procedure in every detail but no fluid injection (sham). Two days after the treatment, an autoradiographic technique was used to investigate the cerebral blood flow (CBF). Findings. Both SAH (blood+ ICP) and saline injection (ICP only) resulted in significantly reduced regional and global CBF after as compared to sham/control. Conclusions. This study revealed that both the elevation of ICP and A Subarachnoid blood per se contribute approximately equally to the SAH induced effects