Long term follow-up of unilateral occlusion of the internal carotid artery including repeated tests of vasomotor reactivity by transcranial Doppler

Abstract

Background: Early study on pathological flow pattern in the ophthalmic artery (OA), connected with impaired vasomotor reactivity (VMR) and low pulsatility index (PI) in the anterior cerebral artery (ACA) on the occluded side, suggested collateral exhaustion. We undertook this study to evaluate whether the occurence of new strokes is predicted by special haemodynamic features.

Method: A total of 27 patients (22 men and five women), aged 63+/-15 years (mean+/-SD) with longstanding occlusion of the internal carotid artery (ICA), confirmed by duplex scanning were studied. They had minimal neurological deficit and were followed-up for mean 4.3+/-1.8 (mean+/-SD) years by repeated clinical and 3-D transcranial Doppler (3-D TCD) examinations with azetazolamide test of vasomotor reactivity (VMR).

Results: During follow-up, seven patients had new strokes (five minor strokes and two major ones), two ipsilateral and four contralateral to the ICA occlusion and one in the posterior circulation. Four patients died, All patients experiencing a new stroke had previous symptoms and pathological flow patterns in the OA, i.e retrograde or isoelectric flow were noted in six of them. One patient with contralateral stroke experienced occlusion of the ICA located above the origin of the OA with anterograde flow; otherwise none of 11 patients with anterograde flow had a new stroke (p<0.05, Fisher exact text). During the follow-up, the initial mean velocity (MV) in the middle cerebral artery (MCA) on the occluded side in six patients with a new stroke in the anterior circulation, was 26.83+/-10.50 cm/s, which was significantly different from that of patients without a new stroke (45.80+/-12.8 cm/s) (p<0.01). MV in the ICA on the non-occluded side at the last examination was greater than that at the first examination (p<0.05) and increased after the use of acetazolamide only on this side (p<0.05), while PI decreased bilateraly (p<0.001 and 0.05). Resting MV both in the MCA on the occluded and ACA on the non-occluded side slightly decreased, while MV in the posterior cerebral artery (PCA) increased on the occluded side (p<0.083) compared with that at the start of the follow-up. VMR in the ACA decreased slightly both on the non-occluded and occluded side (Delta-6.9 and Delta-5.3 respectively), while impaired VMR<or=11% was not significantly connected with new strokes.

Conclusion: During the follow up, new strokes had appeared on both sides and in vertebrobasilar territory and were connected with pathological flow pattern in the OA and low MV in the MCA at the first examination.