[Hemodynamics of intracranial arteriovenous angiomas]

Intracranial arteriovenous malformations (AVM) show haemodynamically two characteristics: The shunt flow and the perfusion of brain tissue surrounding AVM's. In principle, only tissue perfusion can be measured with the stable-Xe-CT method. In 1954 Murphy defined the steal phenomenon in connection with AVM's. It could therefore be concluded that the AVM shunt perfusion works at the expense of tissue perfusion. This phenomenon has been shown to be responsible for serious episodes of neurological deficits in patients with AVM's. In the present report the haemodynamic influence of the AVM's on the surrounding tissue perfusion was measured with the stable-Xe-CT method which offered high resolution with a precise anatomical correlation. A total of 58 stable-Xe-CT studies were performed on 28 patients, 16 of them postoperatively. In 14 patients not only cerebral blood flow at rest but also regional cerebrovascular reserve capacity after intravenous administration of 1 g Diamox were evaluated. Of the 28 patients, 7 had small (nidus < 4 cm), 16 medium (nidus 4-6 cm), and 5 large (nidus > 6 cm) AVM's. In small and medium AVM's we could demonstrate that blood flow at rest did not differ between both hemispheres. After AVM resection the haemodynamics on both sides were not changed. The regional cerebrovascular reactivity following Diamox administration was 20 ml/100 g/min on the side of AVM compared with 40 ml/100 g/min on the contralateral side. Although this difference was statistically significant, it was within the 95% confidence interval of the normal Diamox reactivity.(ABSTRACT TRUNCATED AT 250 WORDS)