[Doppler ultrasonic evaluation of the efficiency of extra-intracranial anastomoses]

We report on the results obtained by means of directional continuous-wave Doppler sonography in 33 patients with superficial temporal-to-middle cerebral artery anastomoses. Recurrent transient ischaemic attacks or a recent mild neurological deficit were considered as justification for bypass surgery in cases of angiographically proven occlusions of one or both internal carotids, severe intracranial carotid artery disease, or stenoses and occlusions of the M-1 segment of the middle cerebral artery. The efficiency of the anastomosis was evaluated by the modified Pourcelot indices (relative end-diastolic flow velocity) 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 for sonographic evaluation. All efficient anastomoses, defined by a modified Pourcelot index of at least 0.20 at the edge of the burr-hole, exhibited an average reduction of 0.08 in the relative end-diastolic flow velocity in the common carotid during compression. In the 18 patients with unilateral occlusion of the internal carotid, bypass surgery was predominantly efficacious (by the above criterion) in those patients who showed a reduction in the sum of the modified Pourcelot indices of the remaining brain-supplying arteries of at least 10% as compared with age-matched controls. The subgroups of existing and absent collaterals through the ophthalmic artery did not show any differences with respect to the percentage of efficient anastomoses.(ABSTRACT TRUNCATED AT 250 WORDS)