Cerebrovascular Circulation ; physiology ; Humans ; Microcomputers ; Tomography, X-Ray Computed ; methods

Animals ; Carotid Arteries ; physiology ; Cerebral Angiography ; Cerebral Arteries ; physiology ; Cerebrovascular Circulation ; Humans ; Rats ; Vertebral Artery ; physiology

By using Doppler sensor and pressure sensor, the cerebrovascular stroke detector can be used to measure the blood flow velocity and blood pressure of the carotid artery. In this study, a variety of signal conversion and isolation processing techniques are proposed for processing and feature extraction of the output signals from the sensors. Finally, effective signal output waveforms that can be used to evaluate the cerebrovascular hemodynamics index (CVHI) are obtained, and the sound signal outputs that can reflect the change characteristics of blood flow velocity and blood pressure signals are generated, which realizes the application functional requirements of the detector.
Blood Flow Velocity/physiology* ; Cerebrovascular Circulation/physiology* ; Hemodynamics/physiology* ; Humans ; Stroke ; Technology

OBJECTIVEFollowing traumatic brain injury (TBI), brain tissue that surrounding the regional primary lesion is known as traumatic penumbra; this region may undergo secondary injury and is considered to have the potential to recover. This review aimed to reveal the existence and significance of traumatic penumbra by analyzing all relevant studies concerning basic pathologic changes and brain imaging after TBI.

DATA SOURCESWe collected all relevant studies about TBI and traumatic penumbra in Medline (1995 to June 2013) and ISI (1997 to March 2013), evaluated their quality and relevance, then extracted and synthesized the information.

STUDY SELECTIONWe included all relevant studies concerning TBI and traumatic penumbra (there was no limitation of research design and article language) and excluded the duplicated articles.

RESULTSThe crucial pathological changes after TBI include cerebral blood flow change, cerebral edema, blood-brain barrier damage, cell apoptosis and necrosis. Besides, traditional imaging method cannot characterize the consequences of CBF reduction at an early stage and provides limited insights into the underlying pathophysiology. While advanced imaging technique, such as diffusion tensor imaging (DTI) and positron emission tomography (PET), may provide better characterization of such pathophysiology.

CONCLUSIONSThe future of traumatic brain lesions depends to a large extent on the evolution of the penumbra. Therefore, understanding the formation and pathophysiologic process of the traumatic penumbra and its imaging research progress is of great significant for early clinical determination and timely brain rescue.

Animals ; Apoptosis ; physiology ; Brain ; pathology ; Brain Injuries ; complications ; pathology ; Cerebrovascular Circulation ; physiology ; Humans ; Necrosis ; physiopathology

BACKGROUND: To develop human space exploration, it is necessary to study the effects of an isolated and confined environment, as well as a microgravity environment, on cerebral circulation. However, no studies on cerebral circulation in an isolated and confined environment have been reported. Therefore, we investigated the effects of a 14-day period of confinement in an isolated environment on dynamic cerebral autoregulation. METHODS: We participated in an isolation and confinement experiment conducted by the Japan Aerospace Exploration Agency in 2016. Eight healthy males were isolated and confined in a facility for 14 days. Data were collected on the days immediately before and after confinement. Arterial blood pressure waveforms were obtained using a finger blood pressure monitor, and cerebral blood flow velocity waveforms in the middle cerebral artery were obtained using transcranial Doppler ultrasonography for 6 min during quiet rest in a supine position. Dynamic cerebral autoregulation was evaluated by transfer function analysis between spontaneous variability of beat-to-beat mean arterial blood pressure and mean cerebral blood flow velocity. RESULTS: Transfer function gain in the low- and high-frequency ranges increased significantly (0.54 ± 0.07 to 0.69 ± 0.09 cm/s/mmHg and 0.80 ± 0.05 to 0.92 ± 0.09 cm/s/mmHg, respectively) after the confinement. CONCLUSION: The increases observed in transfer function gain may be interpreted as indicating less suppressive capability against transmission from arterial blood pressure oscillation to cerebral blood flow velocity fluctuation. These results suggest that confinement in an isolated environment for 14 days may impair dynamic cerebral autoregulation. TRIAL REGISTRATION UMIN000020703 , Registered 2016/01/22.
Adult ; Cerebrovascular Circulation ; physiology ; Confined Spaces ; Homeostasis ; physiology ; Humans ; Male ; Middle Aged ; Space Flight ; Young Adult

Aging is a natural process accompanied with a progressive deterioration of cognitive functions. With an aging population, more and more elderly people are suffering from cognitive impairment. Previous studies have paid more attention to the impact of inflammation and oxidative stress on cognitive function during aging. Recently, it has been discovered that neurovascular coupling (NVC), a mechanism regulating cerebral blood flow, may play a significant role in aging-related cognitive impairment. NVC responses regulate the supply of energy substances and oxygen during brain activity, which in turn enhances cognitive function. However, as people grow older, NVC responses gradually weaken, which may be one of the mechanisms underlying aging-induced cognitive impairment. Given the important role of NVC responses in the brain, it is necessary to search for intervention methods that can improve NVC responses and promote cognitive function. Exercise is an effective means to delay aging and improve cognitive function. It also has a certain promoting effect on NVC responses. This article reviews the regulatory mechanisms of NVC responses, the relationship between NVC responses and cognitive function, and explores the effects of aging and exercise intervention on NVC responses, hoping to provide new research ideas for exercise intervention to improve NVC responses and promote cognitive function in the elderly.
Humans ; Aged ; Neurovascular Coupling/physiology* ; Aging ; Cerebrovascular Circulation/physiology* ; Cognition ; Brain

The methods for measurement of blood flow contain dilution, electro-magnetism, nuclear magnetic resonance, Doppler etc. The dilution, which includes heat dilution, 131Xe, etc., can not display the moving blood flow in real-time. The expenses of nuclear magnetic resonance expenses are very high. Electromagnetism must be used in the surgical operation. And ultrasound Doppler can not record other parameters of hemodynamics synchronously. This paper brings up a kind of blood flow measuring method with simple operating rules, dependable performance, and low cost to meet the needs in hemodynamic studies. The differential pressure between stay and fluxion points of the tube is produced in proportion to the square of velocity while fluid flows through the tube. We not only measure blood pressure or transfer drug using the detention catheter with double chamber, but also detect the differential pressure related within blood flow. The result of detecting cerebral blood flow (CBF) in clinical setting shows this method can record the diagram of dynamic blood flow and is a valid was of detecting blood flow for hemodynamic studies.
Blood Flow Velocity ; Cerebrovascular Circulation ; physiology ; Equipment Design ; Hemorheology ; instrumentation ; methods ; Humans ; Middle Aged ; Monitoring, Intraoperative

BACKGROUNDCerebral hyperperfusion syndrome is an important complication of carotid endarterectomy (CEA). An >100% increase in middle cerebral artery velocity (MCAV) after CEA is used to predict the cerebral hyperperfusion syndrome (CHS) development, but the accuracy is limited. The increase in blood pressure (BP) after surgery is a risk factor of CHS, but no study uses it to predict CHS. This study was to create a more precise parameter for prediction of CHS by combined the increase of MCAV and BP after CEA.

METHODSSystolic MCAV measured by transcranial Doppler and systematic BP were recorded preoperatively; 30 min postoperatively. The new parameter velocity BP index (VBI) was calculated from the postoperative increase ratios of MCAV and BP. The prediction powers of VBI and the increase ratio of MCAV (velocity ratio [VR]) were compared for predicting CHS occurrence.

RESULTSTotally, 6/185 cases suffered CHS. The best-fit cut-off point of 2.0 for VBI was identified, which had 83.3% sensitivity, 98.3% specificity, 62.5% positive predictive value and 99.4% negative predictive value for CHS development. This result is significantly better than VR (33.3%, 97.2%, 28.6% and 97.8%). The area under the curve (AUC) of receiver operating characteristic: AUC(VBI) = 0.981, 95% confidence interval [CI] 0.949-0.995; AUC(VR) = 0.935, 95% CI 0.890-0.966, P = 0.02.

CONCLUSIONSThe new parameter VBI can more accurately predict patients at risk of CHS after CEA. This observation needs to be validated by larger studies.

Aged ; Blood Pressure ; physiology ; Cerebrovascular Circulation ; physiology ; Cerebrovascular Disorders ; physiopathology ; Endarterectomy, Carotid ; Female ; Hemodynamics ; physiology ; Humans ; Male ; Middle Aged ; Prospective Studies

Sympathetic neuronal activity is primarily responsible for the neurogenic control of cerebral autoregulation. The stimulation of sympathetic nerves causes both large arterial constriction and small vessel dilation in experimental animals. However, the role of the sympathetic nervous system in the control of cerebral hemodynamics has yet to be clarified in humans. In order to assess the effect of sympathetic activation on human cerebral hemodynamics, we performed a simultaneous transcranial Doppler (TCD) monitoring of bilateral middle cerebral arterial flow velocity in 16 healthy male volunteers (mean age 26) during well-known sympathetic activation measures such as isometric hand-grip exercise (IHE) and cold pressor test (CPT). Blood pressure was checked manually before and at each minute during tests. The mean arterial pressure (MAP) was calculated as (systolic pressure + 2 X diastolic pressure)/3. There was a significant increase in MCA flow velocities during both sympathetic activation tests. The percent increase of diastolic velocity (36% with IHE and 24% with CPT) was significantly higher than systolic velocity (21% with IHE and 9% with CPT). The pulsatility index was significantly decreased during the tests (from 0.75 to 0.58 with IHE and from 0.81 to 0.63 with CPT). These results suggest that sympathetic activation increases MCA flow velocities, related with a reduction in small vessel resistance and/or a constriction of large arteries.
Adult ; Blood Flow Velocity ; Carbon Dioxide/blood ; Cerebral Arteries/physiology* ; Cerebrovascular Circulation* ; Hemodynamics ; Human ; Male ; Sympathetic Nervous System/physiology*

OBJECTIVETo investigate the effect of occlusal reconstruction on blood flow velocity and cerebral oxygen saturation in patients with malocclusion.

METHODSThirty-three patients with malocclusion treated with occlusal reconstruction in Department of Stomatology, Medical School of Huzhou Normal College from Feb 2011 to Oct 2013 were enrolled in the study. The systolic peak flow velocity (vs), end-diastolic peak flow (vd) , mean peak flow velocity (vm) of middle cerebral artery and the oxygen saturation (rScO2) in the brain were detected at rest or chewing status by using transcranial Doppler color ultrasonography and near-infrared spectroscopy, respectively.

RESULTSIn rest state, vm was significantly increased on 3 months after treatment, while vs and vd were significantly increased on 6 months after treatment and rScO2 were increased on 12 months after treatment (P<0.05). In chewing state, vs, vm, and rScO2 were increased on 3 months after treatment, and vd was increased on 6 months after treatment (P<0.05).

CONCLUSIONOcclusal reconstruction can increase blood flow velocity of middle cerebral artery and cerebral oxygen saturation and improve oxygen supply of the brain in patients with malocclusion.

Blood Flow Velocity ; Brain ; blood supply ; physiology ; Cerebrovascular Circulation ; Humans ; Malocclusion ; surgery ; Oxygen ; physiology ; Reconstructive Surgical Procedures ; Ultrasonography, Doppler, Transcranial