scholarly journals Quantification of Arterial, Venous, and Cerebrospinal Fluid Flow Dynamics by Magnetic Resonance Imaging Under Simulated Micro-Gravity Conditions: A Prospective Cohort Study

2020 ◽  
Author(s):  
Arslan Zahid ◽  
Bryn Martin ◽  
Stephanie Collins ◽  
John N. Oshinski ◽  
Christopher Ross Ethier
Keyword(s):  
Cerebrospinal Fluid ◽  
Peak Flow ◽  
Venous Pressure ◽  
Pulse Amplitude ◽  
Flow Dynamics ◽  
Sectional Area ◽  
Csf Flow ◽  
Cross Sectional ◽  
Microgravity Conditions ◽  
Flow Variables

Abstract Background: Astronauts undergoing long-duration spaceflight are exposed to numerous health risks, including Spaceflight-Associated Neuro-Ocular Syndrome (SANS), a spectrum of ophthalmic changes that can result in permanent loss of visual acuity. The etiology of SANS is not well understood but is thought to involve changes in cerebrovascular flow dynamics in response to microgravity. There is a paucity of knowledge in this area; in particular, cerebrospinal fluid (CSF) flow dynamics have not been well characterized under microgravity conditions. Our study was designed to determine the effect of simulated microgravity (head-down tilt [HDT]) on cerebrovascular flow dynamics. We hypothesized that under microgravity conditions simulated by HDT, increased pressure in the intracranial space would alter intracranial CSF and venous flow dynamics by causing: 1) increased venous pressure reflected by increased venous cross-sectional area; and 2) a decrease in cardiac-related pulsatile CSF flow.Methods: In a prospective cohort study, we measured flow in major cerebral arteries, veins, and CSF spaces in fifteen healthy volunteers using phase contrast magnetic resonance (PCMR) before and during 15° HDT.Results: We found a significant increase in venous cross-sectional area with HDT (p=0.005), indicating increased venous pressure, along with a decrease in all CSF flow variables [systolic peak flow (p=0.009), and peak-to-peak pulse amplitude (p=0.001)]. Arterial average flow (p=0.04), systolic peak flow (p=0.04), and peak-to-peak pulse amplitude (p=0.02) all also significantly decreased.Conclusions: These results collectively demonstrate that acute application of 15° HDT caused a reduction in CSF flow variables (systolic peak flow and peak-to-peak pulse amplitude), coupled with an increase in venous CSA suggesting increased venous pressure with HDT.

scholarly journals Quantification of Arterial, Venous, and Cerebrospinal Fluid Flow Dynamics by Magnetic Resonance Imaging Under Simulated Micro-Gravity Conditions: A Prospective Cohort Study

2020 ◽  
Author(s):  
Arslan Zahid ◽  
Bryn Martin ◽  
Stephanie Collins ◽  
John N. Oshinski ◽  
Christopher Ross Ethier
Keyword(s):  
Cerebrospinal Fluid ◽  
Peak Flow ◽  
Pulse Amplitude ◽  
Flow Dynamics ◽  
Venous Congestion ◽  
Sectional Area ◽  
Csf Flow ◽  
Cross Sectional ◽  
Flow Parameters ◽  
Microgravity Conditions

Abstract Background: Astronauts undergoing long-duration spaceflight are exposed to numerous health risks, including Spaceflight-Associated Neuro-Ocular Syndrome (SANS), a spectrum of ophthalmic changes that can result in permanent loss of visual acuity. The etiology of SANS is not well understood but is thought to involve changes in cerebrovascular flow dynamics in response to microgravity. There is a paucity of knowledge in this area; in particular, cerebrospinal fluid (CSF) flow dynamics have not been well characterized under microgravity conditions. Our study was designed to determine the effect of simulated microgravity (head-down tilt [HDT]) on cerebrovascular flow dynamics. We hypothesized that under microgravity conditions simulated by HDT, increased pressure in the intracranial space would alter intracranial CSF and venous flow dynamics by causing: 1) venous congestion reflected by increased venous cross-sectional area; and 2) a decrease in cardiac-related CSF flow oscillations. Methods: In a prospective cohort study, we measured flow in major cerebral arteries, veins, and CSF spaces in fifteen healthy volunteers using phase contrast magnetic resonance (PCMR) before and during 15° HDT. Results: We found a significant increase in venous cross-sectional area with HDT (p=0.005), indicating venous congestion, along with a decrease in all CSF flow parameters [systolic peak flow (p=0.009), peak-to-peak pulse amplitude (p=0.001), and stroke volume (p=0.10)]. Arterial average flow (p=0.04), systolic peak flow (p=0.04), and peak-to-peak pulse amplitude (p=0.02) all also significantly decreased. Conclusions: These results collectively demonstrate that acute application of 15° HDT caused a reduction in CSF flow parameters (systolic peak flow and peak-to-peak pulse amplitude), coupled with an increase in venous CSA suggesting increased venous congestion with HDT.

scholarly journals Quantification of Arterial, Venous, and Cerebrospinal Fluid Flow Dynamics by Magnetic Resonance Imaging Under Simulated Micro-Gravity Conditions: A Prospective Cohort Study

2020 ◽  
Author(s):  
Arslan Zahid ◽  
Bryn Martin ◽  
Stephanie Collins ◽  
John N. Oshinski ◽  
Christopher Ross Ethier
Keyword(s):  
Cerebrospinal Fluid ◽  
Cohort Study ◽  
Magnetic Resonance ◽  
Pulsatile Flow ◽  
Peak Flow ◽  
Pulse Amplitude ◽  
Flow Dynamics ◽  
Csf Flow ◽  
Microgravity Conditions ◽  
Flow Variables

Abstract Background: Astronauts undergoing long-duration spaceflight are exposed to numerous health risks, including Spaceflight-Associated Neuro-Ocular Syndrome (SANS), a spectrum of ophthalmic changes that can result in permanent loss of visual acuity. The etiology of SANS is not well understood but is thought to involve changes in cerebrovascular flow dynamics in response to microgravity. There is a paucity of knowledge in this area; in particular, cerebrospinal fluid (CSF) flow dynamics have not been well characterized under microgravity conditions. Our study was designed to determine the effect of simulated microgravity (head-down tilt [HDT]) on cerebrovascular flow dynamics. We hypothesized that microgravity conditions simulated by HDT would result in increased intracranial pressure (ICP) reflected by increases in CSF pulsatile flow. Methods: In a prospective cohort study, we measured flow in major cerebral arteries, veins, and CSF spaces in fifteen healthy volunteers using phase contrast magnetic resonance (PCMR) before and during 15° HDT.Results: We found a decrease in all CSF flow variables [systolic peak flow (p=0.009), and peak-to-peak pulse amplitude (p=0.001)]. Cerebral arterial average flow (p=0.04), systolic peak flow (p=0.04), and peak-to-peak pulse amplitude (p=0.02) all also significantly decreased. We additionally found a decrease in average cerebral arterial flow (p=0.040). Finally, a significant increase in cerebral venous cross-sectional area with HDT (p=0.005) was also observed. Conclusions: These results collectively demonstrate that acute application of 15° HDT caused a reduction in CSF flow variables (systolic peak flow and peak-to-peak pulse amplitude) which, when coupled with a decrease in average cerebral arterial flow, systolic peak flow, and peak-to-peak pulse amplitude, is consistent with a decrease in cardiac-related pulsatile CSF flow. These results suggest that decreases in cerebral arterial inflow were the principal drivers of decreases in CSF pulsatile flow.

scholarly journals Quantification of Arterial, Venous, and Cerebrospinal Fluid Flow Dynamics by Magnetic Resonance Imaging Under Simulated Micro-Gravity Conditions: A Prospective Cohort Study

2021 ◽  
Author(s):  
Arslan Zahid ◽  
Bryn Martin ◽  
Stephanie Collins ◽  
John N. Oshinski ◽  
Christopher Ross Ethier
Keyword(s):  
Cerebrospinal Fluid ◽  
Cohort Study ◽  
Magnetic Resonance ◽  
Pulsatile Flow ◽  
Peak Flow ◽  
Pulse Amplitude ◽  
Flow Dynamics ◽  
Csf Flow ◽  
Microgravity Conditions ◽  
Flow Variables

Abstract Background: Astronauts undergoing long-duration spaceflight are exposed to numerous health risks, including Spaceflight-Associated Neuro-Ocular Syndrome (SANS), a spectrum of ophthalmic changes that can result in permanent loss of visual acuity. The etiology of SANS is not well understood but is thought to involve changes in cerebrovascular flow dynamics in response to microgravity. There is a paucity of knowledge in this area; in particular, cerebrospinal fluid (CSF) flow dynamics have not been well characterized under microgravity conditions. Our study was designed to determine the effect of simulated microgravity (head-down tilt [HDT]) on cerebrovascular flow dynamics. We hypothesized that microgravity conditions simulated by acute HDT would result in increases in CSF pulsatile flow. Methods: In a prospective cohort study, we measured flow in major cerebral arteries, veins, and CSF spaces in fifteen healthy volunteers using phase contrast magnetic resonance (PCMR) before and during 15° HDT.Results: We found a decrease in all CSF flow variables [systolic peak flow (p=0.009), and peak-to-peak pulse amplitude (p=0.001)]. Cerebral arterial average flow (p=0.04), systolic peak flow (p=0.04), and peak-to-peak pulse amplitude (p=0.02) all also significantly decreased. We additionally found a decrease in average cerebral arterial flow (p=0.040). Finally, a significant increase in cerebral venous cross-sectional area under HDT (p=0.005) was also observed. Conclusions: These results collectively demonstrate that acute application of -15° HDT caused a reduction in CSF flow variables (systolic peak flow and peak-to-peak pulse amplitude) which, when coupled with a decrease in average cerebral arterial flow, systolic peak flow, and peak-to-peak pulse amplitude, is consistent with a decrease in cardiac-related pulsatile CSF flow. These results suggest that decreases in cerebral arterial inflow were the principal drivers of decreases in CSF pulsatile flow.

scholarly journals Quantification of Arterial, Venous, and Cerebrospinal Fluid Flow Dynamics by Magnetic Resonance Imaging Under Simulated Micro-Gravity Conditions

2020 ◽  
Author(s):  
Arslan Zahid ◽  
Bryn Martin ◽  
Stephanie Collins ◽  
John N. Oshinski ◽  
Christopher Ross Ethier
Keyword(s):  
Cerebrospinal Fluid ◽  
Magnetic Resonance ◽  
Pulsatile Flow ◽  
Peak Flow ◽  
Pulse Amplitude ◽  
Flow Dynamics ◽  
Arterial Flow ◽  
Csf Flow ◽  
Microgravity Conditions ◽  
Flow Variables

Abstract Background: Astronauts undergoing long-duration spaceflight are exposed to numerous health risks, including Spaceflight-Associated Neuro-Ocular Syndrome (SANS), a spectrum of ophthalmic changes that can result in permanent loss of visual acuity. The etiology of SANS is not well understood but is thought to involve changes in cerebrovascular flow dynamics in response to microgravity. There is a paucity of knowledge in this area; in particular, cerebrospinal fluid (CSF) flow dynamics have not been well characterized under microgravity conditions. Our study was designed to determine the effect of simulated microgravity (head-down tilt [HDT]) on cerebrovascular flow dynamics. We hypothesized that microgravity conditions simulated by HDT would result in increased intracranial pressure (ICP) reflected by increases in CSF pulsatile flow.Methods: In a prospective cohort study, we measured flow in major cerebral arteries, veins, and CSF spaces in fifteen healthy volunteers using phase contrast magnetic resonance (PCMR) before and during 15° HDT.Results: We found a decrease in all CSF flow variables [systolic peak flow (p=0.009), and peak-to-peak pulse amplitude (p=0.001)]. Cerebral arterial average flow (p=0.04), systolic peak flow (p=0.04), and peak-to-peak pulse amplitude (p=0.02) all also significantly decreased. We additionally found a decrease in average cerebral arterial flow (p=0.040). Finally, a significant increase in cerebral venous cross-sectional area with HDT (p=0.005) was also observed.Conclusions: These results collectively demonstrate that acute application of 15° HDT caused a reduction in CSF flow variables (systolic peak flow and peak-to-peak pulse amplitude) which, when coupled with a decrease in average cerebral arterial flow, systolic peak flow, and peak-to-peak pulse amplitude, is consistent with a decrease in cardiac-related pulsatile CSF flow. These results suggest that decreases in cerebral arterial inflow were the principal drivers of decreases in CSF pulsatile flow.

scholarly journals Quantification of arterial, venous, and cerebrospinal fluid flow dynamics by magnetic resonance imaging under simulated micro-gravity conditions: a prospective cohort study

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Arslan M. Zahid ◽  
Bryn Martin ◽  
Stephanie Collins ◽  
John N. Oshinski ◽  
C. Ross Ethier
Keyword(s):  
Cerebrospinal Fluid ◽  
Cohort Study ◽  
Magnetic Resonance ◽  
Pulsatile Flow ◽  
Peak Flow ◽  
Pulse Amplitude ◽  
Flow Dynamics ◽  
Csf Flow ◽  
Microgravity Conditions ◽  
Flow Variables

Abstract Background Astronauts undergoing long-duration spaceflight are exposed to numerous health risks, including Spaceflight-Associated Neuro-Ocular Syndrome (SANS), a spectrum of ophthalmic changes that can result in permanent loss of visual acuity. The etiology of SANS is not well understood but is thought to involve changes in cerebrovascular flow dynamics in response to microgravity. There is a paucity of knowledge in this area; in particular, cerebrospinal fluid (CSF) flow dynamics have not been well characterized under microgravity conditions. Our study was designed to determine the effect of simulated microgravity (head-down tilt [HDT]) on cerebrovascular flow dynamics. We hypothesized that microgravity conditions simulated by acute HDT would result in increases in CSF pulsatile flow. Methods In a prospective cohort study, we measured flow in major cerebral arteries, veins, and CSF spaces in fifteen healthy volunteers using phase contrast magnetic resonance (PCMR) before and during 15° HDT. Results We found a decrease in all CSF flow variables [systolic peak flow (p = 0.009), and peak-to-peak pulse amplitude (p = 0.001)]. Cerebral arterial average flow (p = 0.04), systolic peak flow (p = 0.04), and peak-to-peak pulse amplitude (p = 0.02) all also significantly decreased. We additionally found a decrease in average cerebral arterial flow (p = 0.040). Finally, a significant increase in cerebral venous cross-sectional area under HDT (p = 0.005) was also observed. Conclusions These results collectively demonstrate that acute application of −15° HDT caused a reduction in CSF flow variables (systolic peak flow and peak-to-peak pulse amplitude) which, when coupled with a decrease in average cerebral arterial flow, systolic peak flow, and peak-to-peak pulse amplitude, is consistent with a decrease in cardiac-related pulsatile CSF flow. These results suggest that decreases in cerebral arterial inflow were the principal drivers of decreases in CSF pulsatile flow.

scholarly journals Assessment of Cerebrospinal Fluid Hydrodynamics Using Magnetic Resonance Imaging in Postcraniospinal Surgery Patients

2021 ◽  
Author(s):  
Pankaj Arora ◽  
Kanica Rawat ◽  
Rajiv Azad ◽  
Kehkashan Chouhan
Keyword(s):  
Magnetic Resonance Imaging ◽  
Cerebrospinal Fluid ◽  
Magnetic Resonance ◽  
Clinical Outcome ◽  
Phase Contrast ◽  
Flow Dynamics ◽  
Resonance Imaging ◽  
Csf Flow ◽  
Group I ◽  
Group Ii

Abstract Objective Aim of this study is to evaluate the effect of craniospinal interventions on cerebrospinal fluid (CSF) flow hydrodynamics and study the correlation of postoperative changes in flow alteration with clinical outcome. Materials and Methods Fifty patients who underwent various craniospinal procedures were studied using conventional and phase-contrast magnetic resonance imaging (PCMRI) protocol. CSF flow quantification was performed at cerebral aqueduct, foramen magnum, C2–3, and D12–L1 vertebral levels with site showing maximal alteration of CSF flow dynamics considered as the region of interest. Velocity encoding was kept at 20 cm/s. Patients with pathology atcraniovertebral junction were considered separately (group I) from others (group II) due to different flow dynamics. Follow-up scans were performed after an interval of 1 month for temporal evaluation of changes in CSF flow dynamics. Results Patients in both groups showed a significant change in peak CSF velocity postoperatively (mean change of 1.34 cm/s in group I and 0.28 cm/s in group II) with bidirectional improvement in flow on cine-phase-contrast qualitative images. Regional pain (82%) and headache (46%) were seen in most of the patients preoperatively. Postoperatively clinical symptoms improved in 59.5%, static in 26.2%, and worsened in 14.3%. In both the groups, an improvement in clinical symptomatology had significant correlation with mean changes in peak CSF velocity postoperatively (p = 0.04 in both groups). Conclusion PCMRI can effectively evaluate changes in CSF flow noninvasively both pre- and postoperatively. This may have potential role in determining clinical outcome and prognosis of patients undergoing procedures in craniospinal axis.

scholarly journals Incidence and Risk Factors for Symptomatic Spinal Epidural Hematoma Following Posterior Thoracic Spinal Surgery in a Single Institute

2020 ◽  
pp. 219256822097914
Author(s):  
Longjie Wang ◽  
Hui Wang ◽  
Zhuoran Sun ◽  
Zhongqiang Chen ◽  
Chuiguo Sun ◽  
...  
Keyword(s):  
Risk Factors ◽  
Cerebrospinal Fluid ◽  
Spinal Surgery ◽  
Cerebrospinal Fluid Leakage ◽  
Sectional Area ◽  
Kyphosis Angle ◽  
Cross Sectional ◽  
Thoracic Spinal ◽  
Local Kyphosis ◽  
Spinal Epidural

Study Design: Case-control study. Objectives: To investigate the incidence of symptomatic spinal epidural hematoma (SSEH) and recognize its risk factors in a cohort of patients undergoing posterior thoracic surgery in isolation. Methods: From January 2010 to December 2019, patients who developed SSEH after posterior thoracic surgery and underwent hematoma evacuation were enrolled. For each SSEH patient, 2 or 3 controls who did not develop SSEH and underwent the same procedures with similar complexity at the same section of the thoracic spine in the same period were collected. The preoperative and intraoperative factors, blood pressure-related factors and radiographic parameters were collected to identify possible risk factors by comparing between the 2 groups. Results: A total of 24 of 1612 patients (1.49%) were identified as having SSEH after thoracic spinal surgery. Compared to the control group (53 patients), SSEH patients had significant differences in the APTT (p = 0.028), INR (p = 0.009), ratio of previous spinal surgery (p = 0.012), ratio of cerebrospinal fluid leakage (p = 0.004), thoracic kyphosis (p<0.05), local kyphosis angle (p<0.05), epidural fat ratio at T7 (p = 0.003), occupying ratio of the cross-sectional area (p<0.05) and spinal epidural venous plexus grade (p<0.05). Multiple logistic regression analysis revealed 3 risk factors for SSEH: cerebrospinal fluid leakage, the local kyphosis angle (>8.77°) and the occupying ratio of the cross-sectional area (>49.58%). Conclusions: The incidence of SSEH was 1.49% in posterior thoracic spinal surgeries. Large local kyphosis angle (>8.77°), high occupying ratio of cross-sectional area (>49.58%) and cerebrospinal fluid leakage were identified as risk factors for SSEH.

scholarly journals Venous compliance and clinical implications

2018 ◽  
Vol 7 (2) ◽  
Author(s):  
Paolo Zamboni ◽  
Valentina Tavoni ◽  
Francesco Sisini ◽  
Massimo Pedriali ◽  
Erika Rimondi ◽  
...  
Keyword(s):  
Venous Pressure ◽  
Vena Cava ◽  
Cross Sectional Area ◽  
Venous System ◽  
Clinical Implications ◽  
Sectional Area ◽  
Venous Compliance ◽  
Cross Sectional ◽  
The Cross ◽  
Deformable System

Compliance is a characteristic of every deformable system. Compliance is very clear concept in physics and mechanics but in clinics, perhaps, is not the same. However, in veins compliance fits perfectly with the function of drainage of the venous system. Volumetric increase (dV) of the content is correlated with pressure increase (dP) inside the vein according to the equation C’= dV/dP. In humans 75% of the blood is located in the venous system, primarily because the molecular components of a vein media layer is significantly more compliant to that of arteries. This property is fundamental to understanding the change in blood volume in response to a change in posture. Measurements of venous compliance in clinical practice can be done by the means of ultrasound, as well as with the plethysmography. Ultrasound methods assimilate the cross sectional area to the volume of the vein, because it reflects the blood content. Changes in cross sectional area can be reliably measured in response to a change in posture, while pressure can be derived from the hydrostatic pressure changes. Venous compliance is of paramount importance also in pulsatile veins such as the inferior or superior vena cava and the jugular veins, where high resolution ultrasound may accurately derive the cross sectional area. Clinical implications of the mechanical properties of the venous wall are extensively discussed, including the need of dedicated venous stenting, which takes into account venous compliance as the main parameter of the venous function. In addition, venous compliance is the interpretative key for a better understanding of plethysmography curves, as well as of varicose veins and of their return to normal cross sectional area following ambulatory venous pressure reduction.

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