Angiographic vasospasm and release of platelet thromboxane after subarachnoid hemorrhage.

We studied adenosine diphosphate-induced platelet aggregation and the associated release of thromboxane B2 in 49 patients with subarachnoid hemorrhage in relation to angiographic vasospasm. Postoperative cerebral angiography was performed less than or equal to 3 (median 1) days after surgery for an aneurysm 5-14 days after subarachnoid hemorrhage. Correspondingly, one sample from each patient was taken within 24 hours either before or after angiography. The occurrence of severe as well as diffuse, moderate, or severe angiographic vasospasm was associated with the presence of delayed cerebral ischemia (p less than 0.05). Patients with diffuse angiographic vasospasm had significantly higher (p less than 0.05) values for thromboxane B2 release than the others, even after adjustment by the clinical grades on admission and before surgery, the timing of surgery, the time from subarachnoid hemorrhage to angiography and blood sampling, and nimodipine therapy. Severe and diffuse angiographic vasospasm were also associated with poor outcome at 1 year (p less than 0.05). Our results suggest that augmented release of platelet thromboxane may be involved in the pathogenesis of vasospasm in large cerebral arteries.