Experimental cerebral vasospasm. Part 2: effects of vasoactive drugs and sympathectomy on early and late spasm.

The authors report the effects of vasoactive drugs and sympathectomy on experimental spasm using vertebral angiography. Papaverine and isoxsuprine injections into the vertebral artery released both early and late spasm. The antiserotonin agent, methysergide, adn the alpha adrenergic blocking agent, phentolamine, released early but not late spasm. In sympathathectomized dogs, early spasm was milder than in untreated dogs; however, late spasm was the same as in untreated dogs. The authors discuss an etiological difference between early and late spasm.