In neurosurgical operations, such as cerebral aneurysm clipping, bypass surgery and arteriovenous malformations, monitoring of cerebral blood flow is critically important. Currently, surgeons do not have real-time noninvasive methods for intraoperative visualization of cerebral blood flow. Laser speckle contrast imaging (LSCI), widely used in the diagnosis of blood flow, may be promising for solving this problem. In the present study, the LSCI was demonstrated for the evaluation of acute cerebral blood flow abnormalities in laboratory animals. To visualize cerebral blood flow, the rats underwent cranial trepanation. The disruption of cerebral blood circulation was simulated by clamping both common carotid arteries through the neck approach. A specially designed LSCI system was used to assess blood flow. A distinct reduction in blood flow in the cerebral cortex after carotid artery clipping was shown, which lasted for 10 min continuously. At the same time, a more intensive blood flow decrease was observed in the right hemisphere, which can be related to the blood supply of the left hemisphere through the circle of Willis. After the clips were removed, blood flow in both hemispheres was restored to a level higher than the initial level. The results obtained show the prospects of using LSCI for the control of acute disorders of cerebral blood flow during neurosurgical operations in real-time.
The aim of the study was to compare the metabolic activity of brain cortex after the acute hypoxia caused by the impairment of breathing or blood circulation. Male Wistar rats were randomized in two groups: impaired breathing and blood circulation failure groups. Fluorescence under 365 and 450 nm excitation and diffuse reflectance intensity at 550-820 nm range were estimated. We found that after long-term hypoxic conditions, notable metabolic changes occur. We suppose that oxygen deficiency causes an activation of the GABA shunt mechanism. In cases of blood circulation failure, fluorescence intensity changes faster than in cases of breathing impairment.
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