RUPTURED INTRACRANIAL ANEURYSMS--THE ROLE OF ARTERIAL SPASM.

I N A RECENT PAPER t h e a u t h o r s L d i s cussed the findings of pos topera t ive angiography carried out rout inely on pat ients with ruptured intracranial aneurysms. I t was felt t ha t arterial spasm was one of the chief reasons for pos topera t ive morb id i ty and mortal i ty , and in this paper the problem is considered fur ther wi th regard to cause and effect. Attent ion is given also to earlier manifestations of arterial spasm, whether operation was under taken or not. I t has been suggested t ha t vasospasm is an optical illusion. However , when a vessel, previously shown to be of normal calibre, la ter appears thread-l ike in two or more projections (Figs. 1 and ~), it is ha rd to accept t ha t this could be a t t r ibu ted to a physical phenomenon such as l aminar flow of contrast mater ia l in the ar tery . Taveras 1~ accepted the occurrence of spasm but considered it to be the result of the introduction of rad iopaque cont ras t material into an a r te ry a l ready i r r i ta ted by some other cause. There are several points against this theory. (1) This effect is seldom seen in postoperat ive angiograms of pa t ients who have had tumours removed. I n such pat ients the arteries m a y have been injured and blood will be present in the subarachnoid space. In cases of rup tured aneurysms these are two of the conditions t ha t migh t predispose arteries to spasm. (2) T h e subst i tut ion of Thoro t ras t , which is general ly accepted as being nonirr i ta t ing to vessels, for contrast media containing iodine, does not alter the appearances. In a series of radiographs showing spasm the cont ras t mate r ia l appears to be d a m m e d back so t h a t any par t icular ar tery