Spasm of Basilar and Vertebral Arteries Caused by Experimental Subarachnoid Hemorrhage

Abstract

I N THE present exper iments on monkeys, marked spasm of the basilar and vertebral arteries, somet imes result ing in cessation of respiration and death, was produced: 1) When arterial blood was merely irrigated onto these vessels af ter opening the araehnoid widely over the cisterna pontis; ~) when subaraehnoid bleeding surrounding these vessels was produced b y rupture of a t iny pial vessel with a needle; 3) when subaraehnoid hemorrhage into the basal cisterns occurred as a result of a blow to the animal 's head; and 4) following applicat ion to one of these vessels of a t iny pledger of cottonoid soaked in fresh blood. Since the middle of the nineteenth century , m a n y observers have suggested on empirical grounds, t ha t spasm of cerebral vessels might play a role in epilepsy, migraine, t empora ry hemiplegia, hypesthesias , aphasias, and other t r ans i to ry neurologic phenomena. Although there is a b u n d a n t evidence tha t both pial 4~ and in t racerebra l arteries 2s are supplied with nerves, these vessels do not constrict more t han abou t 8 to 10 per cent on st imulation of the cervical sympathe t ic nerves. ~5'~6 Skin vessels on the other hand contract 80 per cent following similar stimulation of sympathe t i c fibres2 ~ Evidence tha t some dilatation of pial vessels occurs on stimulation of the vagus nerve, providing the facial nerve is intact, was supplied by Chorobski and Penfield, 5 and Cobb and Finesinger. ~ In contrast to the findings cited above, Florey 14 reported in detail how marked spasms could be produced in individual pial vessels over the convexities of the cerebral hemispheres in cats b y direct mechanical and