Evaluation of the Basilar Artery Flow Velocity by TCD Examination

概要

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We measured flow velocities of the basilar artery (BA) via the suboccipital window by TCD in 115 subjects to investigate BA hemodynamics. Twenty one of the subjects had posterior circulation pathology, 37 had anterior circulation pathology, and the remaining 57 cases had no lesions. The vascular lesion was confirmed by cerebral angiography in all cases. The characteristic findings of the BA flow velocity by the site of vascular lesion were as follows. 1) Normal: signal obtainable from a depth of 80 mm to depths beyond 95 mm. Timeaveraged mean velocity was between 20 and 45 cm/s and velocity variations occurred at different depths<16 cm/s. 2) BA occlusion: a) Total occlusion: no signal or signal only from the site adjacent to the vertebrobasilar junction. b) Distal occlusion: continuous low velocity (<20 cm/s) .c) Proximal occlusion: continuous retrograde flow. 3) Stenosis of the BA: sudden increase in flow velocity at the stenotic portion or continuous low velocity proximal to the site of severe stenosis. 4) Occlusion of the bilateral vertebral arteries (VA) : flow from the anterior spinal artery detectable. 5) Unilateral occlusion of the VA: no distinctive flow pattern. 6) Internal carotid artery occlusion or vascular rich tumor in the posterior lobe: increased flow velocity along the BA. 7) Other anterior circulation pathology: no characteristic signal.