CHARACTERIZATION OF AN ANTERIOR CIRCULATION RAT SUBARACHNOID HEMORRHAGE MODEL

Background ann Purpose Our aim was to demonstrate the feasibility of a n angiographically controlled rat model for the study of macrocirculat ory and microcirculatory changes of the anterior intracranial circulat ion after subarachnoid hemorrhage. Methods Subarachnoid hemorrhage was induced by transorbital injection of 0.3 mL of nonheparinized autolog ous arterial blood into the chiasmatic cistern. Changes in regional ce rebral blood flow were continuously recorded with the use of laser-Dop pler flowmetry over the parietal cortex. Angiographic verification of middle cerebral artery diameter was performed by carotid catheterizati on at baseline and 2 days after injection of blood or artificial cereb rospinal fluid. We monitored intracranial and systemic blood pressure during and after injections. Results Injection of artificial cerebrosp inal fluid in the control group did not change the diameter of the mid dle cerebral artery. Injection of blood caused a significant arterial narrowing of 17.5%, from 0.37+/-0.04 mm to 0.31+/-0.04 mm after 2 days (P=.0001). In the control group regional cerebral blood flow decrease d to 75.9+/-16.8% of preinjection control but quickly recovered to 99. 7+/-19.4%. Intracranial pressure increased for 5 minutes after the inj ection to a maximum of 27.3+/-8.9 mm Hg, accompanied by a 10% decrease in mean arterial pressure. A fall in cerebral blood Bow to 53.1+/-26. 3% in blood-injected animals that recovered to only 80.7+/-16.9% of ba seline values during the observation period of 30 minutes was noted. A peak intracranial pressure of 45.7+/-11.5 mm Hg occurred 2. minutes a fter injection with a decrease in mean arterial pressure of 13%, resul ting in a markedly lower cerebral perfusion pressure than in the contr ol group. Conclusions An angiographically controlled model of subarach noid hemorrhage primarily involving the anterior circulation is feasib le in the rat. The resulting narrowing of the middle cerebral artery r eflects moderate vasospasm and will allow further microcirculatory stu dies with cranial windows.