Magnetic resonance imaging evaluation of subarachnoid hemorrhage in rats and the effects of intracisternal injection of papaverine and nitroglycerine in the management of cerebral vasospasm

Abstract

Background: Cerebral vasospasm is a major cause of morbidity and mortality after subarachnoid hemorrhage (SAH). It usually occurs about 3-9 days after SAH. The pathogenesis involves the release of endogenous spasmogens. Though various treatment modalities are available, none are really effective. Aims and Objectives: The aim of the study was to develop an effective animal model for the study of SAH and vasospasm as well as to study the efficacy of vasodilators, namely nitroglycerine and papaverine, on SAH-induced vasospasm using magnetic resonance angiography. Materials and Methods: Fifteen Wistar albino rats, weighing around 150-200 gm were used for the study. Five rats served as controls of SAH-induced vasospasm, while five rats each were used to study the efficacy of intracisternal injection of papaverine or nitroglycerine. Results: Rats demonstrate vasospasm in a manner similar to humans. The maximal vasospasm is seen in the basilar artery. Statistical analysis demonstrates an improvement in vasospasm after instillation of intracisternal papaverine at the end of 2 hours in basilar and left internal cerebral artery. However, nitroglycerine does not produce any significant amelioration of vasospasm. Thus, it can be deduced that the pathogenesis of the vasospasm is more due to the action of cGMPase enzyme rather than inhibition of nitric oxide (NO) synthetase by the spasmogens. The present study is the first study in the English literature to compare the effects of single bolus doses of nitroglycerine and papaverine using magnetic resonance angiography. Conclusion: Rats can be used to create an effective model for SAH-induced vasospasm as the pattern resembles human SAH. Papaverine is an effective drug for ameliorating SAH-induced vasospasm. Short-acting NO donors are not as effective in ameliorating vasospasm.