Original scientific paper
The influence of vertebral artery occlusion on visual evoked responses in posterior cerebral artery
Marijana Bosnar Puretić
Arijana Lovrenčić-Huzjan
Marina Roje-Bedeković
Vida Demarin
Abstract
Stroke is the second leading cause of death and the leading cause of disability in Croatia. One-quarter of all ischemic strokes occur in the posterior circulation. One third of ischemic strokes are caused by large artery diseases. Transcranial Doppler sonography (TCD) is a non-invasive method with an excellent temporal resolution for real time investigations of cerebral hemodynamics and, among other methods, functional TCD tests are very useful tools for establishing the cerebral vasomotor capacity. TCD studies revealed that a proximal stenosis in the carotid circulation severely influences distal cerebral hemodynamics and autoregulative mechanisms.
The aim of this study was to establish the influence of a vertebral artery (VA) occlusion on visual evoked responses in the posterior cerebral artery (PCA) measured by means of TCD.
We measured mean blood flow velocities (MBFVs) in the PCA before and during a visual stimulation in patients with a VA occlusion by means of TCD.
Without visual stimuli there was no significant difference between the control group and the patients with a VA occlusion. During white light stimulation a statistically significant increase of MBFVs in the PCA in both groups occurred. In the control group the increase was 22.85±20.9% for the right PCA and 20.67±15.31% for the left PCA. In the group of patients with a VA occlusion the increase in the right PCA was 12.3±16.46% and in the left PCA 11.89±13.08%. In the patients with a VA occlusion repeated testing led to diminished responses, which could be an indicator of the exhaustion of the cerebrovascular vasomotor reserve.
Based on the results of our study we can conclude that there is a negative effect on the functioning of the distal small vessels in the case of a VA occlusion. Visually evoked functional TCD testing is a non-invasive and precise method for the estimation of vasoreactivity in the posterior circulation.
Keywords
vertebral artery; visual evoked responses; sonography; posterior cerebral artery
Hrčak ID:
17453
URI
Publication date:
10.10.2007.
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