Effect of age on cerebral blood flow velocity and incidence of vasospasm after aneurysmal subarachnoid hemorrhage

Background and Purpose-Current transcranial Doppler criteria for vasospasm after aneurysmal subarachnoid hemorrhage are not age specific. We analyzed the effect of age on cerebral blood flow velocity changes after subarachnoi d hemorrhage and constructed an age-adjusted predictive model of cerebral b lood flow velocity in subarachnoid hemorrhage patients, Methods-We identified patients with aneurysmal subarachnoid hemorrhage admi tted between 1991 and 1999 with a prospective transcranial Doppler database . Eighty-one patients, with complete medical records and transcranial Doppl er examinations of the vessels of interest, were included. Patients were su bdivided into 2 groups by age: younger, <68 years of age (n = 47) and older , <greater than or equal to>68 years of age (n = 34). Maximum mean flow vel ocity and incidence of symptomatic vasospasm were reported. Linear and nonl inear regression analyses were performed. Results-Middle cerebral artery and internal carotid artery mean flow veloci ty were lower in older patients (median 76 versus 114 cm/s and 76 versus 12 6 cm/s, respectively; P < 0.003). Incidence of symptomatic vasospasm was lo wer in older patients (44% versus 66%; P = 0.05). Older patients developed symptomatic vasospasm at lower middle cerebral artery (median 57 versus 103 cm/s; P = 0.04) and internal carotid artery (median 54 versus 81 cm/s, P = 0.02) mean flow velocity. Relationship between middle cerebral artery and internal carotid artery mean flow velocity and age was quadratic (ANOVA, P < 0.0001). Conclusions-Older patients have a lower incidence of symptomatic vasospasm, and such vasospasm develops at lower cerebral blood flow velocity than you nger patients. A quadratic relationship was found between age and cerebral blood flow velocity. This model could be used to create an age-adjusted nom ogram that might improve diagnostic capabilities of transcranial Doppler.