Diluted Papaverine for Microvascular Protection of Cranial Nerves

Abstract

Silent cerebral vasospasm following surgical resection of vestibular schwannomas is much more common than previously thought. This might mean that the cerebral circulation shows a high reactivity to surgical trauma, and it can be hypothesized that this happens not only in elastic and muscular arteries but also in arterioles—and especially those within the cerebellopontine angle. From this perspective, prevention of vasospasm is useful for microvascular protection of the cranial nerves. Papaverine is known to be a potent vasodilator directly acting on smooth muscle and causing it to relax. Intra-arterial administration of papaverine has been used to treat arterial vasospasm after aneurysmal subarachnoid hemorrhage. When applied topically, it acts as a smooth muscle relaxant to break intraoperative vasospasm. The most important side effects of topical papaverine in vestibular schwannoma surgery are transient palsies of facial and cochlear nerves. It has been proposed that intracisternal papaverine at a concentration of 0.3% would be reasonably safe.