Transcranial Doppler assessment of the functional effects of symptomatic carotid stenosis.

Mean flow velocity changes in the middle cerebral arteries (MCAs) during a 2-minute thumb-to-finger opposition task were measured by means of transcranial Doppler ultrasonography in patients with severe unilateral carotid stenosis and ipsilateral transient ischemic attacks and in control subjects. The increase of flow velocity in the MCA contralateral to the hand performing the task was significantly different (p < 0.001, one-way ANOVA) in controls (+5.52 +/- 2.4 cm/sec) and in patients (+1.76 +/- 1.6 cm/sec, side of stenosis; +3.83 +/- 2.1 cm/sec, normal side). A post hoc least significant difference test revealed a significant difference between controls and patients on the side of stenosis (p < 0.001) and between the normal side and the stenotic side in patients (p < 0.03). One month after carotid endarterectomy, the effect of the motor task produced a significantly different effect on flow velocity in patients (p < 0.01, two-way ANOVA) because the increase of flow 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 task on flow velocity of MCAs may allow for the evaluation of the functional effects of carotid lesions. Prospective studies are needed to evaluate whether this test constitutes a useful approach for the identification of patients who would benefit from a surgical procedure.