CHANGES IN CEREBRAL BLOOD-FLOW INDUCED BY BALLOON TEST OCCLUSION OF THE INTERNAL CAROTID-ARTERY UNDER HYPOTENSION

Balloon test occlusion (BTO) of the internal carotid artery (ICA) comb ined with cerebral blood flow (CBF) study has proved to be a sensitive test for prediction of the outcome of permanent vessel occlusion, In this study, we evaluated the acute changes in regional CBF during BTO under hypotension in order to examine the possible risk of cerebral is chaemia after surgical treatment. Eleven patients in whom surgical car otid sacrifice was planned underwent BTO combined with CBF studies usi ng technetium-99m hexamethyl-propylene amine oxime single-photon emiss ion tomography under hypotension by decreasing the systemic blood pres sure by about 50 mm Hg using a ganglion blocking agent, All patients s howed a mild to severe decrease in CBF in the ipsilateral ICA territor y relative to the contralateral side. A decrease in CBF of greater tha n 20% was observed in nine patients (82%), and two of them showed a de crease exceeding 40%, However, no ischaemic symptoms were demonstrated during scanning with hypotensive BTO. Our results suggest that in man y patients with negative normotensive BTO, a considerable reduction in CBF would occur during hypotension, This procedure may predict a poss ible risk of hypotensive accident during and/or after surgery.