Clinical observations on the effect of carotid artery occlusion on cerebral blood flow mapped by xenon computed tomography and its correlation with carotid artery back pressure

Abstract

Xenon computed tomographic cerebral blood flow mapping was correlated with internal carotid artery stump pressures and clinical neurologic assessment during temporary internal carotid artery occlusion. One hundred fourteen patients with skull base tumors or intracranial aneurysms potentially requiring carotid resection or ligation underwent angiography, xenon CT cerebral blood flow mapping, and internal carotid artery blood pressure monitoring. The internal carotid artery was then temporarily occluded with a balloon catheter, stump pressure was measured through the catheter, and the xenon CT cerebral blood flow mapping was repeated. Adequate xenon CT cerebral blood flow was defined as >30 cc/100 gm/min. All patients had normal xenon CT cerebral blood flow before internal carotid artery occlusion. During internal carotid artery occlusion, xenon CT cerebral blood flow was found to be normal (group I, 40 patients), globally reduced but still within the normal range (group II, 50 patients), or low in the distribution of the ipsilateral middle cerebral artery (group III, 13 patients). With balloon occlusion, an immediate neurologic deficit developed in 11 patients (9%) requiring deflation of the balloon preceding xenon CT cerebral blood flow measurement (group IV). In group I internal carotid artery blood pressure was 128 mm Hg. (range 85 to 171 mm Hg) with stump pressure 86 mm Hg (range 46 to 125 mm Hg). In group II internal carotid artery blood pressure was 130 mm Hg. (range 78 to 199 mm Hg), with stump pressure 86 mm Hg (range 31 to 150 mm Hg). In group III internal carotid artery blood pressure was 135 mm Hg (range 95 to 194 mm Hg) with stump pressure 64 mm Hg (range 37 to 106 mm Hg). In group IV internal carotid artery blood pressure was 117 mm Hg (range 90 to 148 mm Hg), with stump pressure 62 mm Hg (range 23 to 100 mm Hg) p < 0.01 for stump pressure groups I and II versus III and IV. During subsequent operations one of the 23 patients in groups I and II requiring carotid occlusion or ligation had a stroke, but four of five patients (80%) in groups III and IV had strokes after internal carotid artery occlusion or resection. Although stump pressure correlates with xenon CT cerebral blood flow mapping, the wide range precludes its use alone as an absolute predictor of adequate cerebral blood flow after carotid occlusion. In addition, xenon CT cerebral blood flow mapping and trial internal carotid artery balloon occlusion are of value in predicting the hemodynamic consequences of carotid ligation.