engleski

Functional Testing Of Posterior Cerebral Circulation With Light

Objective: Visual stimulation influences mean blood flow velocities (MBFV) in posterior cerebral arteries. Using transcranial Doppler (TCD) we measured MBFV in posterior cerebral arteries (PCA) in healthy volunteers with eyes open, closed and during watching white, flashing white light, red, yellow, green and blue light. Methods: MBFV was measured using transcranial doppler sonography in both posterior cerebral arteries in 51 healthy volunteer with eyes open, eyes closed, and while they were looking white light, flashing white light, red, yellow, green and blue light. In the group there were 27 males (52, 9 %) and 24 females (47, 1 %). All volunteers were right-handed, aged between 20 and 59 years, mean age was 36, 98 years. In the half of volunteers measurements started on the right side, and continued on the left side, while in the other half measurements started on the left side, and continued on the right side. Statistical analysis was performed using Wilcoxon matched pairs signed-ranks test. Results: MBFV mean value in left posterior cerebral artery was 41, 2 ± 8, 6 cm/s while volunteers had eyes open. Closing the eyes caused a drop of MBFV mean value to 27, 8 ± 8, 5 cm/s (67, 5 % of the value with eyes open). During looking at white light MBFV mean value was 42, 3 ± 9, 1 cm/s (102, 7 %), while watching flashing white light MBFV mean value was 42, 3 ± 9, 1 cm/s (104, 4 %), while watching red and yellow light MBFV mean value was 31, 4 ± 7, 1 and 31, 4 ± 7, 2cm/s, respectively, (76, 2 %), while watching green light MBFV mean value was 32, 0 ± 8, 3 cm/s (77, 7 %), and while watching blue light MBFV mean value was 33, 0 ± 7, 6 cm/s (80, 1 %). There was statistically significant difference between MBFV mean value with eyes open and in all other states (eyes closed, white light, flashing white light, and all colors). MBFV mean value in right posterior cerebral artery was 41, 7 ± 8, 9 cm/s while volunteers had eyes open. Closing the eyes caused a drop of MBFV mean value to 28, 2 ± 9, 1 cm/s (67, 6 % of the value with eyes open). During looking at white light MBFV mean value was 42, 4 ± 8, 8 cm/s (101, 7 %), while watching flashing white light MBFV mean value was 43, 4 ± 9, 2 cm/s (104, 1 %), while watching red light MBFV mean value was 39, 4 ± 8, 4 cm/s (94, 5 %), while watching yellow MBFV mean value was 38, 9 ± 9, 2 cm/s (93, 3 %), while watching green MBFV mean value was 37, 8 ± 9, 4 (90, 7%) and while watching blue light MBFV mean value was 38, 0 ± 8, 8 cm/s (91, 1 %). No statistically significant difference was found between MBFV mean values with eyes open and while Watching white light, but there were statistically significant difference between MBFV mean values with eyes open and in all other states (eyes closed, flashing white light, and all colors). No statistically significant difference was found between MBFV mean values in left and right posterior cerebral artery with eyes open, eyes closed, while watching white light and flashing white light. But there were statistically significant higher MBFV mean values in right posterior cerebral artery during watching all colors, than MBFV mean values in left posterior cerebral artery. That could indicate the greater importance of right cerebral visual cortex in the perception of colors. The difference was most prominent with colors of longer wavelength (red), and it lessens with colors of shorter wavelength (blue). Conclusion: These findings could indicate the greater metabolism of visual cortex in right occipital lobe while watching colors suggesting that visual cortex of right occipital lobe could have greater role in color perception than visual cortex of left occipital lobe. This study showed that monitoring the changes in MBFV with transcranial Doppler is a very good method that can significantly widen our knowledge about cerebral homodynamic. This method is simple, harmless, painless, noninvasive and has excellent time resolution and it gains data in real time.

posterior cerebral circulation; functional transcranial Doppler; visual stimulation

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