Cross-filling of circle of Willis and carotid stenosis by angiography, duplex ultrasound, and oculopneumoplethysmography.

PURPOSE: To evaluate the filling of the Circle of Willis on preoperative arteriograms and to correlate this observation with the results of oculopneumoplethysmography (OPG) and severity of carotid stenosis as determined by duplex ultrasonography and angiography.

PATIENTS AND METHODS: Ninety-five patients underwent OPG, duplex ultrasonography, and selective carotid and vertebral arteriography.

RESULTS: In all, 45 (88%) patients with a positive OPG had interhemispheric cross-filling of the middle cerebral artery and anterior cerebral artery from a contralateral carotid injection in contrast with 10 (23%) patients with a negative OPG (P < 0.001). Of patients with carotid stenosis > or = 80% on duplex ultrasound, 39 (91%) had cross-filling from a contralateral carotid injection in contrast with 16 (31%) patients with < 80% stenosis (P < 0.001). Of patients with carotid stenosis > or = 80% on arteriogram, 37 (90%) had cross-filling from a contralateral carotid injection in contrast with 18 (33%) patients with < 80% stenosis (P < 0.001).

CONCLUSION: These data suggest that the Circle of Willis is frequently incompetent as a collateral pathway and that arteriographic cross-filling is not a reliable index of this pathway. Patients with a positive OPG and corresponding carotid stenosis are likely to have a physiologically incompetent collateral pathway. Perhaps these patients should undergo surgery, even if the stenosis is less than 80%.