The efficacy of EC-IC anastomoses: evaluation by directional c-w Doppler sonography

We report the results obtained by means of directional c-w Doppler sonography on 33 patients with superficial temporal-to-middle cerebral artery anastomoses. The efficiency of the anastomosis was evaluated by the modified Pourcelot indices (relative end-diastolic flow velocities) of the preauricular superficial temporal artery and of the bypass-supplying branch at the edge of the burr-hole. The influence of intermittent compression of the bypass-supplying branch on the modified Pourcelot index of the ipsilateral common carotid was used as a further criterion in the sonographic evaluation. All efficient anastomoses, defined by a modified Pourcelot index of at least 0.20 at the edge of the burr-hole, exhibited a reduction of the relative end-diastolic flow velocity of 0.08 on the average in the common carotid during compression. In the 18 cases with unilateral occlusion of the internal carotid, bypass surgery was predominantly efficacious in those patients who showed a reduction in the sum of the modified Pourcelot indices of the remaining brain-supplying arteries of at least two standard deviations with respect to the mean of age-matched controls. The subgroups of patent and absent collaterals through the ophthalmic artery did not show any difference with respect to the percentage of efficient anastomoses. In all 4 patients with bilateral internal carotid artery occlusion, bypass surgery was effective, while 50% of the patients with intracranial carotid artery disease exhibited an insufficient anastomosis.(ABSTRACT TRUNCATED AT 250 WORDS)