The effect of intrathecal sodium nitroprusside on severe chronic vasospasm.

The efficacy of sodium nitroprusside in resolving cerebral vasospasm was evaluated with multicisternal injections. Twelve animals received fresh, unheparinized arterial blood via three injections (15 ml total) into the cisterna magna. Selective vertebral arteriography was performed on Day 0, and blood injections were performed on the second and third days after the first injection. On the seventh day selective arteriography was performed to evaluate the diameter of the basilar artery. In the sodium nitroprusside group, intrathecal injections of the drug were started on Day 4 and continued for two days (25 micrograms/kg/day). The diameter of the basilar artery was reduced 72.98 +/- 11.07% in control experiments. For the animals treated with intrathecal sodium nitroprusside, the mean diameter of the basilar artery was reduced 29.25 +/- 4.54%. The effect of intrathecal sodium nitroprusside on intracranial pressure (ICP), blood pressure (BP) and electrocardiogram (ECG) was also evaluated in 14 animals. There were no prominent changes in ICP, BP, or ECG when sodium nitroprusside was given intrathecally, but BP decreased and ICP and heart rate increased with intravenous doses of sodium nitroprusside. These results support the hypothesis that sodium nitroprusside administered intrathecally is an effective treatment for cerebral vasospasm.