Effect of intra-arterial papaverine on cerebral blood flow in vasospasm after subarachnoid hemorrhage: A study using single-photon emission computed tomography.

Cerebral vasospasm is an important cause of delayed stroke after subarachnoid hemorrhage. Single-photon emission computed tomography (SPECT) of regional cerebral blood flow with (99m)Tc-hexamethyl propylenenamine oxime (HMPAO) was performed before and after intra-arterial papaverine treatment in 10 patients with symptomatic cerebral vasospasm. Two patients were treated twice. The ultimate clinical outcome was improved due to papaverine in 5 of the 10 patients. SPECT imaging correlated with clinical course in 10 of 12 treatments. One of the discordant cases had significant residual mesial frontal lobe perfusion defects on SPECT despite improvement in blood flow in the lateral aspects of the frontal lobes and did not improve clinically. The other was stable but required definitive treatment with balloon angioplasty on the following day before clinical improvement was noted. Papaverine has effectiveness in pharmacologically dilating constricted cerebral arteries and is preferred for distal vasospasm and in vessels that may be difficult to dilate via balloon angioplasty. Technetium-99m-HMPAO SPECT imaging detects cerebral perfusion deficits associated with vasospasm and monitors the effect of intra-arterial papaverine on regional cerebral blood flow.