Visually Evoked Changes of Blood Flow Velocity and Pulsatility Index in the Posterior Cerebral Arteries: A Transcranial Doppler Study
| Autor: | Harders A, Aschoff A, Wiedensohler R, Kuchta J, Klug N |
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| Rok vydání: | 2004 |
| Předmět: |
Adult
Male medicine.medical_specialty Visual perception genetic structures Ultrasonography Doppler Transcranial Cerebral arteries Pulsatile flow Posterior cerebral artery Internal medicine medicine.artery Computer Graphics medicine Humans Aged Visual Cortex Posterior Cerebral Artery business.industry Blood flow Middle Aged Transcranial Doppler Visual cortex medicine.anatomical_structure Cerebrovascular Circulation Cardiology Vascular resistance Evoked Potentials Visual Female Surgery Neurology (clinical) business Photic Stimulation Psychomotor Performance |
| Zdroj: | Zentralblatt für Neurochirurgie. 65:13-17 |
| ISSN: | 1438-9746 0044-4251 |
| Popis: | OBJECTIVE Transcranial Doppler sonography (TCD) can detect visual evoked blood flow responses non-invasively and continuously with high temporal resolution. While the mean flow velocity response to visual stimuli is well documented, the response of the pulsatile characteristics of the waveform is less well known. METHOD We examined the changes of blood flow velocity and pulsatility index (PI) in the posterior cerebral artery (PCA) in 50 healthy volunteers. TCD responses were measured in response to metabolic activation of the visual cortex by visual stimulation. RESULTS A specific, stimulus-related increase of the mean flow velocity (MFV) in the PCA was found. The intensity of the blood flow response was significantly influenced by the complexity of the stimulus. During complex visual stimulation we found a mean flow velocity (MFV) increase of 29.4 % from the baseline in the subjects. However, a stimulus-related decrease was observed in the pulsatility index (PI); although the mean PI with closed eyes during baseline measurement was 1.18 (SD 0.27), on average, it fell significantly to 0.95 (SD 0.23) with the alternating chessboard and 0.82 (SD 0.22) during the complex stimulus condition. The relative decrement of the pulsatility index with increasing complexity of the visual stimulus is highly significant, with values of -19.5 % and -30.5 % compared to the baseline. CONCLUSION These findings demonstrate the inverse correlation between MFV response and pulsatility index in the PCA. We assume that this decrease of the PI in the PCA may reflect the reduced regional vascular resistance in the visual cortex during visual stimulation. |
| Databáze: | OpenAIRE |
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