REGIONAL CEREBRAL BLOOD-VOLUME AFTER SEVERE HEAD-INJURY IN PATIENTS WITH REGIONAL CEREBRAL-ISCHEMIA

OBJECTIVE: Recent early cerebral blood flow (CBF) studies in cases of severe head injury have revealed ischemia in a substantial number of p atients with a variety of computed tomographically demonstrated diagno ses. The underlying derangements causing this early ischemia are unkno wn, but cerebral blood volume (CBV) measurements might offer some insi ght into this pathological abnormality. METHODS: For this purpose, sta ble xenon-enhanced computed tomography was used for assessment of CBF, and a dynamic computed tomographic imaging technique was used for det ermining CBV. Based on the occurrence of regional ischemia (CBF < 20 m l/100 g/min), seven patients with varying anatomic lesions revealed by computed tomography were identified for comparison between CBF and CB V in ischemic and nonischemic areas. RESULTS: Both CBF (15 +/- 4.3 ver sus 34 +/- 11 g/min, P < 0.002) and CBV (2.5 +/- 1.0 versus 4.9 +/- 1. 9 ml/100 g) exhibited significantly lower values in the ischemic zones than in the nonischemic zones (means +/- standard deviations). Among 26 patients with or without ischemia observed during their initial fol low-up studies, which were conducted between Days 2 and 8, all patient s showed CBF and CBV values within the low-normal range. CONCLUSION: T hese data evidently support the suggestion that compromise of the micr ovasculature is the cause of early ischemia, rather than vasospasm of the larger conductance vessels.