Neurologic evaluation in a canine model of single and double subarachnoid hemorrhage

The pathophysiology of cerebral vasospasm is complex and multifactorial. The present study sought to identify the degree of correlation between cerebral vasospasm as observed angiographically and clinical evaluation of an animal's neurologic status in the canine model following a single and double experimental subarachnoid hemorrhage (SAH) protocol. Nineteen mongrel dogs underwent single or double experimental SAH by percutaneous needle puncture of the cisterna magna and placement of a subarachnoid blood clot in the basal cistern on day 1 and day 4, respectively. At 72 h after each experimental SAH, vertebral angiography was performed and compared to control angiography. Basilar artery diameter measured at multiple positions was expressed as percentage of control diameter. Clinical evaluation of the animals was performed every day throughout the experiments. To assess the degree of neurologic impairment we developed a coma scale that efficiently estimated motor ability, eye response and eating habits of the animals. Vasoconstriction after experimental SAH reduced mean basilar artery diameter to 79.1% (+/- 5.4) of control diameter following single SAH and to 69.0% (+/- 2.1) of control diameter following double SAH. No changes were observed in the neurologic behavior of the animals throughout the experiment. Since a principal characteristic of human cerebral vasospasm is the close correlation between arterial constriction and neurological deficit, we believe that the canine model of SAH, although good in creating cerebral arterial vasoconstriction, does not fully represent the best model of human cerebral vasospasm.