engleski

The role of TCD in the evaluation of collatreral circulation in the vertebrobasilar territory

Background: Collateral circulation plays an important role in the development of neurological symptoms. The aim of this study was to evaluate patients with the occlusion of extracranial part of vertebral arteries (VAs) with neurological symptoms and collateral circulation by TCD. Methods and patients: A total of 58 patients (70+/-8 yrs, 38 male, 20 female) with vertebral artery occlusion (VAO - 32 right and 26 left) were studied. Non of the VAs contralateral to the occluded side was hypoplastic (< 2 mm in diameter). The extracranial part of VA in all patients was examined by CDFI. The mean blood flow velocities (MBFV) in the intracranial part of vertebral arteries was obtained by TCD. Asymmetry of mean blood flow velocities between the right and left VA was calculated. Decreased MBFV in VAs was defined as < 26 cm/s, normal 27 - 49 cm/s and increased MBFV as > 50 cm/s. Neurological symptoms were compared with TCD findigs. Results: Decreased MBFV ipsilateral to VAO was found in 19 patients (33, 3%), normal MBFV in both VAs was found in 17 patients (29, 8%), decreased MBFV in both VAs in 11 patients (19, 2%), increased MBFV ipsilateral to VAO in 4 patients (7%), and 2 (3, 5%) patients had either increased MBFV in both VAs, decreased MBFV in contralateral VA or increased MBFV contralateral to VAO. Six patients additionaly had carotid artery stenosis: 3 ipsilateral to VAO and all had decreased MBFV in ipsilateral VA, 1 patient had bilateral increase of MBFV, 1 patient with ipsilateral carotid artery stenosis had increased MBFV and 1 had MBFV within normal ranges. The most frequent symptoms in patients were: dizziness, motor deficit, nausea, headache, dysarthria, cognitive disturbances, visual field deficit, paresthesia. Strong correlation between VAO, transcranial findings of MBFV and neurological symptoms has been observed. Conclusions: Sufficient collateral circulation is an important factor in the development of neurological symptoms in patients with vertebral artery occlusion. Transcranial Doppler is a usefull screening method in the evaluation of collateral pathways of intracranial circulation.

collateral circulation; vertebrobasilar

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