Effect of diltiazem on experimental chronic cerebral vasospasm in the monkey.

The influence of diltiazem on chronic cerebral vasospasm was studied following subarachnoid hemorrhage (SAH) in a primate model. The model mimics the human experience including the production of neurological deficits. Six monkeys were pretreated with diltiazem (25 mg/kg twice daily) for 2 days prior to surgical production of an SAH and for 5 days after the hemorrhage. This group was compared with six untreated monkeys that also sustained an SAH. The mean diameter of cerebral arteries measured at six angiographic sites was 60.6% of the pre-SAH diameter for the untreated group and 99.7% for the diltiazem-treated group. These values are significantly different (p less than 0.0005). There was no neurological deficit in the pretreated animals. The mean diameter of the "most constricted vessel" in each experiment was 22% of the prehemorrhage diameter for the untreated and 84% for the treated group (p less than 0.0005). Arterial pressure was unaffected by the dosage regimen. These experiments with this primate model of chronic cerebral vasospasm demonstrate that vascular narrowing and neurological deficit can be markedly attenuated by diltiazem pretreatment.