TRANSCRANIAL DOPPLER ASSESSMENT OF CEREBROVASCULAR REACTIVITY IN SYMPTOMATIC AND ASYMPTOMATIC SEVERE CAROTID

Background and Purpose Some studies have suggested a link between impa ired cerebral hemodynamics and stroke in pa patients with carotid sten osis. The aim of this study was to assess the effects of severe caroti d stenosis on cerebrovascular reactivity and the possible changes afte r endarterectomy. Methods Using bilateral transcranial Doppler ultraso und, we studied the changes of flow velocity after hypercapnia in the middle cerebral arteries of 10 control subjects and 24 patients (13 sy mptomatic and 11 asymptomatic) with unilateral severe carotid stenosis before and after endarterectomy. Cerebrovascular reactivity was evalu ated with the breath-holding index (BHI). Results Before endarterectom y, BHI (mean value +/- SD) was significantly lower (P < .001) in the s tenotic side of symptomatic patients (0.40 +/- 0.2) than in control su bjects (1.12 +/- 0.3). the stenotic side of asymptomatic patients (0.8 0 +/- 0.4), and the normal side of both symptomatic (0.93 +/- 0.3) and asymptomatic ultrasonics (1.03 +/- 0.2) patients. On the other hand, no significant difference in BHI was detected in control subjects, on the normal side of symptomatic and asymptomatic patients, and the sten otic side of asymptomatic patients. After endarterectomy. BHI signific antly increased (P < .0001) on the stenotic side of symptomatic patien ts (1.06 +/- 0.2) while remaining substantially stable on the normal s ide of both symptomatic and asymptomatic patients and on the stenotic side of asymptomatic patients. Conclusions These findings suggest that the study of cerebrovascular reactivity to hypercapnia may be relevan t in evaluating the functional effects of carotid stenosis. Further in vestigations are needed to confirm the reliability of the breath-holdi ng method in the selection of patients who might benefit most from car otid endarterectomy.