TRANSCRANIAL DOPPLER ASSESSMENT OF THE FUNCTIONAL-EFFECTS OF SYMPTOMATIC CAROTID STENOSIS

Mean flow velocity changes in the middle cerebral arteries (MCAs) duri ng a 2-minute thumb-to-finger opposition task were measured by means o f transcranial Doppler ultrasonography in patients with severe unilate ral carotid stenosis and ipsilateral transient ischemic attacks and in control subjects. The increase of flow velocity in the MCA contralate ral to the hand performing the task was significantly different (p < 0 .0011 one-way ANOVA) in controls (+5.52 +/- 2.4 cm/sec) and in patient s (+1.76 +/- 1.6 cm/sec, side of stenosis; +3.83 +/- 2.1 cm/sec, norma l side). A post hoc least significant difference test revealed a signi ficant difference between controls and patients on the side of stenosi s (p < 0.001) and between the normal side and the stenotic side in pat ients (p < 0.03). One month after carotid endarterectomy, the effect o f the motor task produced a significantly different effect on flow vel ocity in patients (p < 0.01, two-way ANOVA) because the increase of fl ow velocity during the motor task on the side of stenosis (4.84 +/- 1. 9 cm/sec) was similar to that observed on the normal side (4.63 +/- 1. 4 cm/sec). These findings suggest that the effect of a simple motor ta sk on flow velocity of MCAs may allow for the evaluation of the functi onal effects of carotid lesions. Prospective studies are needed to eva luate whether this test constitutes a useful approach for the identifi cation of patients who would benefit from a surgical procedure.