PREDICTING HEMODYNAMIC ISCHEMIA BY TRANSCRANIAL DOPPLER MONITORING DURING THERAPEUTIC BALLOON OCCLUSION OF THE INTERNAL CAROTID-ARTERY

PURPOSE: Our objective was to evaluate the sensitivity of transcranial Doppler (TCD) sonographic monitoring during permanent balloon occlusi on of the internal carotid artery (ICA) in predicting hemodynamic isch emia, METHODS: Thirty-two consecutive patients underwent controlled th erapeutic balloon occlusion of the ICA, Selection criteria included as sessment of the circle of Willis by compression angiography, clinical tolerance during a 20-minute test occlusion, and TCD monitoring of the ipsilateral middle cerebral artery, The mean blood flow velocity (MBF V) (n = 32) and pulsatility index (PI) (n = 28) were recorded, In 25 p atients, MBFV changes upon motor stimulation were recorded before and after ICA occlusion. RESULTS: Twenty-eight (88%) of the patients had n o complications, Three patients suffered delayed symptoms 30 minutes t o 20 hours after balloon detachment, Two of these patients recovered s pontaneously within 1 dag, the other improved after extracranial/intra cranial (EC/ IC) bypass surgery. One patient, who did not tolerate the test occlusion, suffered a hemodynamic stroke despite EC/IC bypass be fore permanent balloon occlusion, No embolic complications occurred. T he mean MBFV reduction was 20% (range, 0% to 55%); the mean PI reducti on was 20% (range, 0% to 56%). No complications occurred in patients w ho had mild MBFV and PI reduction (30% or less, n = 21), All three pat ients with severe MBFV or PI reduction (> 50%) had neurologic symptoms , Among those with moderate MBFV or PI reduction (30% to 50%, n=8), sy mptoms developed in only one patient who had moderate reduction of bot h MBFV (33%) and PI (38%), Motor vasoreactivity showed wide variation and was markedly reduced in two symptomatic patients, CONCLUSION: TCD monitoring reflects changes in cerebral hemodynamics after therapeutic balloon occlusion of the ICA, MBFV and PI reductions under 30% are hi ghly predictive of clinical tolerance, A reduction of more than 50% ma y be a critical threshold for the occurrence of symptoms; in such case s, EC/IC bypass should be considered before proceeding with permanent balloon occlusion.