engleski

Impaired visually evoked response in posterlor cerebral artery in patients wlth advanced carotid stenosis or occlusion

Up to now vasoreactivity testing was almost always performed investigating middle cerebral artery or rearly anterior cerebral artery, showing similar reactivity in both. Testing of posterior circulation using visual stimuli was described only in few studies, mostly on healthy individuals, although visual stimulation is noninvasive, and the most powerful stimuli of metabolism in visual cortex. The aim of the study was to investigate visual evoked response in posterior cerebral artery (PCA) in patients with carotid disease. Mean blood flow velocities (MBFV) of the PCA were investigated in patients with advanced carotid stenosis or occlusion by means of transcranial Doppler (TCD), 2 MHz probe MultiDop X4 DWL. Velocities were measured successivcly in the dark and during white light visual stimulation thrce times. Mean reaction changes in MBFV compared to dark in all stimulations were calculated. Mean reaction time (time to peak velocities) was measured. The data were compared with 8 healthy controls. We investigated 16 male patients: 8 with subtotal intemal carotid artery (ICA) stenosis (5 right, 3 left), 5 ICA occlusion (2 right, 3 left), and 3 patients with bilateral stenosis or occlusion. During light stimulation mean MBFV increase was 46, 56 _+2, 56% on the right and 44, 13_+3, 01% on the left. In healthy controls right PCA MBFV increase was 44, 71_+6, 5%, and 42, 67_+6, 65% on the left. Mean reaction time in patients with carotid disease was 26, 79_+6, 72 s in the right PCA, and 27, 06+7, 6s in the left PCA. In healthy controls mean reaction time was 15+_3, 3 s in the right and 15_+3, 3 s in thc left PCA (p<0.05). TCD testing using visual stimuli showed prolonged visual evoked response in patients with carotid discase, although MBFV changes didn't differ compared to healthy controls. TCD testing using visual stimuli is an usefull method in the evaluation of vascular reserve capacity in patients with carotid discase.

evoked response; carotid disease; posterior cerebral artery

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