CEREBRAL BLOOD-FLOW RESPONSE PATTERN DURING BALLOON TEST OCCLUSION OFTHE INTERNAL CAROTID-ARTERY

PURPOSE: To evaluate the risk of temporary or permanent internal carot id artery occlusion. METHODS: In 156 patients intraarterial balloon te st occlusion in combination with a stable xenon-enhanced CT cerebral b lood flow study was performed before radiologic or surgical treatment. All 156 patients passed the clinical balloon test occlusion and under went a xenon study in combination with a second balloon test. Quantita tive flow data were analyzed for absolute changes as well as changes i n symmetry. RESULTS: Fourteen patients exhibited reduced flow values b etween 20 and 30 mL/100 g per minute, an absolute decrease in flow, an d significant asymmetry in the middle cerebral artery territory during balloon test occlusion. These patients would be considered at high ri sk for cerebral infarction if internal carotid artery occlusion were t o be performed. With one exception they belonged to a group (class I) of 61 patients who showed bilateral or ipsilateral flow decrease and s ignificant asymmetry with lower flow on the side of occlusion. The oth er 95 patients, who showed a variety of cerebral blood flow response p atterns including ipsilateral or bilateral flow increase, were at mode rate (class II) or low (class III) stroke risk. In contrast to these f indings, exclusively qualitative flow analysis failed to identify the patients at high risk: a threshold with an asymmetry index of 10% reve aled only 16% specificity whereas an asymmetry index of 45% showed onl y 61% sensitivity for detection of low flow areas (<30 mL/100 g per mi nute). CONCLUSION: For achieving a minimal hemodynamic related-stroke rate associated with permanent clinical internal carotid artery occlus ion we suggest integration of a thorough analysis of quantitative cere bral blood flow data before and during balloon test occlusion.