Sequential changes in the platelet count in patients with symptomatic vasospasm after subarachnoid hemorrhage.

The platelet count in 110 patients with subarachnoid hemorrhage (SAH) was analyzed retrospectively. Changes in the platelet count in 102 patients undergoing intracranial aneurysm surgery showed that the minimum platelet count was similar in patients with and without symptomatic vasospasm, but the minimum occurred later in symptomatic vasospasm patients, regardless of Hunt and Hess grade or operation timing. Sixty-five of 67 non-symptomatic vasospasm patients (97%) showed the minimum platelet count within 4 days of SAH and two (3%) on the 5th day. In contrast, only 10 of 35 symptomatic vasospasm patients (29%) showed a minimum platelet count within 4 days after SAH and 25 (71%) between the 5th and 11th days. Analysis of the eight patients not receiving surgery showed that the minimum platelet count occurred 2 days after SAH in two non-symptomatic vasospasm patients, but after the 5th day in five of six symptomatic vasospasm patients. Therefore, monitoring of the platelet count can provide an indicator of the occurrence of symptomatic vasospasm.