Noninvasive measurement of cerebral vasopasm in patients with subarachnoid hemorrhage

Abstract

Regional cerebral blood flow (rCBF) was measured as fast flow clearance (F 1) and the initial slope index (ISI 2) after inhalation of 133Xe in 30 patients with subarachnoid hemorrhage (SAH). Vasomotor responsiveness to reduction in end-tidal PECO 2 was examined in those patients who could carry out this procedure satisfactorily as a test for the presence or absence of vasospasm. F 1 and ISI 2 were significantly reduced in patients with recent SAH compared to 35 age-matched normal volunteers. The degree of reduction of F 1 and ISI 2 correlated directly with severity of the neurological deficit graded according to the Hunt and Hess rating scale. Topographic reductions of rCBF correlated with angiographically demonstrated vasospasm or intracerebral hematoma. The degree of impairment of cerebral vasomotor responsiveness to reduction of PECO 2 by hyperventilation also correlated with the severity of vasospasm demonstrated angiographically in 16 patients. The reductions of rCBF values were maximal during the first week after SAH but returned gradually toward normal by the 5th week. Individual patients with SAH whose lowest F 1 values were above 50 ml 100 g brain/ min tolerated surgical intervention best. Non-invasive measurements of rCBF after SAH appear to be helpful in estimating the presence and time course of vasospasm, in recognizing the development of normal pressure hydrocephalus, and in planning medical and surgical management.