Cerebrospinal Fluid Flow Rate Research Articles

Near-Infrared-II Imaging Revealed Hypothermia Regulates Neuroinflammation Following Brain Injury by Increasing the Glymphatic Influx.

Advanced in vivo imaging techniques have facilitated the comprehensive visual exploration of animal biological processes, leading to groundbreaking discoveries such as the glymphatic system. However, current limitations of macroscopic imaging techniques impede the precise investigation of physiological parameters regulating this specialized lymphatic transport system. While NIR-II fluorescence imaging has demonstrated advantages in peripheral lymphatic imaging, there are few reports regarding its utilization in the glymphatic system. To address this, a noninvasive transcranial macroscopic NIR-II fluorescence imaging model is developed using a cyanine dye-protein coupled nanoprobe. NIR-II imaging with high temporal and spatial resolution reveals that hypothermia can increase the glymphatic influx by reducing the flow rate of cerebrospinal fluid. In addition, respiratory rate, respiratory amplitude, and heart rate all play a role in regulating the glymphatic influx. Thus, targeting the glymphatic influx may alter the trajectory of immune inflammation following brain injury, providing therapeutic prospects for treating brain injury with mild hypothermia.

Effect of nitric oxide modulators on cerebrospinal fluid outflow through the cribriform plate of C57Bl/6 mice

Introduction. Beside the excretion of metabolic wastes, the lymphatic system in CNS play a crucial role in the regulation of intracranial pressure that is vital for the organism. One of the possible pathways of cerebrospinal fluid (CSF) drainage is its flow through the foramen of the cribriform plate (CP) into the nasal cavity. Despite the significant contribution of the nasal tract to the overall dynamics of the liquor, not much is known about the mechanisms of this process and how it is regulated. Due to its influence on the tone of blood vessels and peristalsis of lymphatic vessels, nitric oxide (NO) is a powerful modulator of liquor outflow, but its effects on nasal CSF outflow have not been studied yet. Aim and Methods. Using diffusion-weighted magnetic resonance imaging (DW MRI), we characterized the changes in CSF outflow through the CP of C57Bl/6 mice influenced by intranasal application of NO synthesis modulators. Results. In our study, using DW MRI and computer tomography (CT) mapping of the CP, we detected significant CSF outflow through its large dorsal and ventral foramen located along the nasal septum. At the same time, the CSF flow rate through the dorsal orifices of the CP was the highest. In addition, we showed that intranasal introduction of NO donor after 30 min leads to a significant decrease of water diffusion through the CP whereas application of a nonspecific NO synthase inhibitor into the nasal cavity enhances nasal outflow. The effects of the NO modulators did not have any significant spatial patterns; CSF outflow was significantly altered across all CP orifices regardless of their size or localization. Conclusion. The obtained results demonstrate the potential possibility of noninvasive local regulation of liquor dynamics, which may be used in the development of new approaches to the therapy of intracranial hypertension of various etiologies and methods of CNS detoxification.

A novel ventriculoperitoneal shunt flow sensor based on electrically induced spatial variation in cerebrospinal fluid charge density.

Introduction: Ventriculoperitoneal (VP) shunts divert cerebrospinal fluid (CSF) out of cerebral ventricles in patients with hydrocephalus or elevated intracranial pressure (ICP). Despite high failure rates, there exist limited clinically viable solutions for long-term and continuous outpatient monitoring of CSF flow rate through VP shunts. We present a novel, low-power method for sensing analog CSF flow rate through a VP shunt premised on induced spatial electrical charge variation. Methods: Two geometric variants of the proposed sensing mechanism were prototyped: linear wire (P1) and cylindrical (P2) electrodes. Normal saline was gravity-driven through P1 and a commercially available shunt system in series. True flow rates were measured using a high-precision analytical balance. Subsequently, artificial CSF was driven by a programmable syringe pump through P2. Flow rate prediction models were empirically derived and tested. Sensor response was also assessed during simulated obstruction trials. Finally, power consumption per flow measurement was measured. Results: P1 (17mm long) and P2 (22mm long) averaged 7.2% and 4.2% error, respectively, in flow rate measurement from 0.01 to 0.90mL/min. Response curves exhibited an appreciably flattened profile during obstruction trials compared to non-obstructed states. P2 consumed 37.5 µJoules per flow measurement. Conclusion: We propose a novel method for accurately sensing CSF flow rate through a VP shunt and validate this method at the benchtop with normal saline and artificial CSF over a board range of flows (0.01-0.90mL/min). The sensing element is highly power efficient, compact, insertable into existing shunt and valve assemblies, and does not alter CSF flow mechanics.

CSIG-27. FLUID SHEAR STRESS ACTIVATES A MECHANO-METASTATIC CASCADE TO PROMOTE MEDULLOBLASTOMA METASTASIS

Abstract Medulloblastoma (MB) is the most common malignant pediatric brain tumor. Dissemination of MB cells into cerebrospinal fluid (CSF) and blood initiates metastasis in the central nervous system, which significantly worsens patient prognosis. Disseminated MB cells survive the nutrient-deprived CSF environment and are subjected to fluid shear stress (FSS) by CSF flow. Whether and how FSS contributes to MB metastasis is completely unknown. We computationally simulated FSS dynamics in MB patients using MRI-informed CSF flow models. Based on CSF flow rates and force magnitudes in patients, we engineered two FSS application systems: (1) an orbital shaker system that applies FSS to large populations of cells, and (2) a microfluidic system compatible with live-cell and high-resolution imaging. By applying physiologically relevant FSS to MB cells, we discovered that FSS-treated MB cells metastasize more frequently and form larger metastatic tumors along the spinal cords of mice. Mechanistically, FSS induces actomyosin contraction, which promotes cell clustering, glucose transporter 1 (GLUT1) localization at the cell surface, and GLUT1-dependent glucose uptake. FSS elevates intracellular calcium through mechanosensitive ion channel PIEZO2, which is required for FSS-induced actomyosin contraction, cell clustering, and GLUT1 activity. Genetically perturbing PIEZO2 or pharmacologically inhibiting GLUT1 robustly suppresses MB metastasis in mice. Collectively, we discover that MB cells perceive FSS, define an FSS-activated mechano-metastatic cascade, and demonstrate that this cascade is clinically targetable to mitigate MB metastasis.

Impact of continuous-flow mechanical circulatory support on cerebrospinal fluid motility.

Mechanical circulatory support (MCS), including ventricular assist devices (VADs), have emerged as promising therapeutic alternatives for end-stage congestive heart failure (CHF). The latest generation of these devices are continuous flow (CF) blood pumps. While there have been demonstrated benefits to patient outcomes due to CF-MCS, there continue to be significant clinical challenges. Research to-date has concentrated on mitigating thromboembolic risk (stroke), while the downstream impact of CF-MCS on the cerebrospinal fluid (CSF) flow has not been well investigated. Disturbances in the CSF pressure and flow patterns are known to be associated with neurologic impairment and diseased states. Thus, here we seek to develop an understanding of the pathophysiologic consequences of CF-MCS on CSF dynamics. We built and validated a computational framework using lumped parameter modeling of cardiovascular, cerebrovascular physics, CSF dynamics, and autoregulation. A sensitivity analysis was performed to confirm robustness of the modeling framework. Then, we characterized the impact of CF-MCS on the CSF and investigated cardiovascular conditions of healthy and end-stage heart failure. Modeling results demonstrated appropriate hemodynamics and indicated that CSF pressure depends on blood flow pulsatility more than CSF flow. An acute equilibrium between CSF production and absorption was observed in the CF-MCS case, characterized by CSF pressure remaining elevated, and CSF flow rates remaining below healthy, but higher than CHF states. This research has advanced our understanding of the impact of CF-MCS on CSF dynamics and cerebral hemodynamics.

Biomechanical effects of hyper-dynamic cerebrospinal fluid flow through the cerebral aqueduct in idiopathic normal pressure hydrocephalus patients

Normal pressure hydrocephalus (NPH) is an intracranial disease characterized by an abnormal accumulation of cerebrospinal fluid (CSF) in brain ventricles within the normal range of intracranial pressure. Most NPH in aged patients is idiopathic (iNPH) and without any prior history of intracranial diseases. Although an abnormal increase of CSF stroke volume (hyper-dynamic CSF flow) in the aqueduct between the third and fourth ventricles has received much attention as a clinical evaluation index in iNPH patients, the biomechanical effects of this flow on iNPH pathophysiology are poorly understood. This study aimed to clarify the potential biomechanical effects of hyper-dynamic CSF flow through the aqueduct of iNPH patients using magnetic resonance imaging-based computational simulations. Ventricular geometries and CSF flow rates through aqueducts of 10 iNPH patients and 10 healthy control subjects were obtained from multimodal magnetic resonance images, and these CSF flow fields were simulated using computational fluid dynamics. As biomechanical factors, we evaluated wall shear stress on the ventricular wall and the extent of flow mixing, which potentially disturbs the CSF composition in each ventricle. The results showed that the relatively high CSF flow rate and large and irregular shapes of the aqueduct in iNPH resulted in large wall shear stresses localized in relatively narrow regions. Furthermore, the resulting CSF flow showed a stable cyclic motion in control subjects, whereas strong mixing during transport through the aqueduct was found in patients with iNPH. These findings provide further insights into the clinical and biomechanical correlates of NPH pathophysiology.

Noninvasive Calculation of Cerebrospinal Fluid Production Using Phase-Contrast Magnetic Resonance Imaging: First Implementation in Augusta, Georgia.

This retrospective review examines the utility of phase-contrast magnetic resonance imaging (PC-MRI) to calculate flow through the aqueduct between the third and fourth ventricles to estimate cerebrospinal fluid (CSF) production. Imaging software quantified the CSF flow rate across the aqueduct of four females and two males at a single center, and the mean of these results was compared to the established mean CSF production calculated by invasive techniques. There was no significant difference between the means, contributing to the body of literature suggesting the utility of PC-MRI in estimating CSF production rates.

SEGMENTATION OF SPINAL SUBARACHNOID LUMEN WITH 3D ATTENTION U-NET

Phase Contrast Magnetic Resonance Image (PC-MRI) is an emerging noninvasive technique that contains pulsatile information by measuring the parameters of cerebrospinal fluid (CSF) flow. As CSF flow quantities are measured from the selected region on the images, the accuracy in the identification of the interested region is the most essential, and the examination requires a lot of time and experience to analyze and for accurate CSF flow assessment. In this study, a three-dimensional (3D)-Unet architecture, including pulsatile flow data as the third dimension, is proposed to address the issue. The dataset contains 2176 phase and rephase images from 57 slabs of 39 3-tesla PC-MRI subjects collected from the lower thoracic levels of control and Idiopathic Scoliosis (IS) patients. The procedure starts with labeling the CSF containing spaces in the spinal canal. In the preprocessing step, unequal cardiac cycle images (i.e., frame) and the numbers of MRIs in cases are adjusted by interpolation to align the temporal dimension of the dataset to an equal size. The five-fold cross-validation procedure is used to evaluate the 3D Attention-U-Net model after training and achieved an average weighted performance of 97% precision, 95% recall, 98% F1 score, and 95% area under curve. The success of the model is also measured using the CSF flow waveform quantities as well. The mean flow rates through the labeled and predicted CSF lumens have a significant correlation coefficient of 0.96, and the peak CSF flow rates have a coefficient of 0.65. To our knowledge, this is the first fully automatic 3D deep learning architecture implementation to segment spinal CSF-containing spaces that utilizes both spatial and pulsatile information in PC-MRI data. We expect that our work will attract future research on the use of PC-MRI temporal information for training deep models.

Blood and cerebrospinal fluid flow oscillations measured with real-time phase-contrast MRI: breathing mode matters

BackgroundCervical blood and cerebrospinal fluid (CSF) flow rates can be quantified with Phase-contrast (PC) MRI, which is routinely used for clinical studies. Previous MRI studies showed that venous and CSF flow alterations are linked to various pathological conditions. Since it is well known that, besides the heart beating, the thoracic pump influences the blood and CSF dynamics, we studied the effect of different respiration modes on blood and CSF flow rates using a real-time (RT)-PC prototype.MethodsThirty healthy volunteers were examined with a 3 T scanner. A RT-PC sequence was acquired at the first cervical level to quantify the flow rates of internal carotid arteries, internal jugular veins (IJVs) and CSF. Each RT-PC acquisition was repeated three times, while the subjects were asked to breathe in three different ways for 60 s each: freely (F), with a constant rate (PN) and with deep and constant respiration rate (PD). The average flow rates were computed, they were removed from the respective signals and integrated in the inspiratory and expiratory phases (differential volumes). Finally, the power spectral density was computed for each detrended flow rate. High- and very-high frequency peaks were identified on the spectra while their frequencies were compared to the respiratory and cardiac frequencies estimated using a thoracic belt and a pulse oximeter. The area under the spectra was computed in four 0.5 Hz-wide ranges, centered on the high-frequency peak, on very-high frequency peak and its 2nd and 3rd harmonics, and then they were normalized by the flow rate variance. The effect of breathing patterns on average flow rates, on systolic and diastolic peaks, and on the normalized power was tested. Finally, the differential volumes of inspiration were compared to those of expiration.ResultsThe frequencies of the high- and very-high spectral peaks corresponded to the respiratory and cardiac frequencies. The average flow rate progressively decreased from F to PN to PD breathing, and the cardiac modulations were less predominant especially for the IJVs. The respiratory modulation increased with PD breathing. The average volumes displaced in the inspiratory phases were not significantly different from those of the expiratory one.ConclusionsThe spectral analyses demonstrated higher respiratory modulations in PD compared to free breathing, even prevailing the cardiac modulation in the IJVs, showing an increment of the thoracic pump affecting the flow rate shape.

Ventricular and lumbar cerebrospinal fluid analysis in 77 HIV-negative patients with Cryptococcal meningitis who received a ventriculoperitoneal shunt.

Lumbar cerebrospinal fluid (CSF) parameters are widely studied and have wide clinical applications, but ventricular CSF has rarely been studied since it is relatively difficult to obtain. To determine whether there are differences between ventricular and lumbar CSF parameters and whether the differences have clinical significance, we retrospectively reviewed 77 patients with Cryptococcal meningitis who received a ventriculoperitoneal shunt. We analyzed the following parameters: white blood cell count, total protein concentration, CSF/blood glucose ratio, chloride ion concentration, and Cryptococcal count. All parameters between lumbar and ventricular CSF were remarkably different (all p < 0.001). White blood cell count, total protein level and Cryptococcal count were lower in ventricular CSF than in lumbar CSF, while CSF/blood glucose ratio and chloride ion concentration were higher. Compared to patients without ventriculomegaly, patients with ventriculomegaly had a significantly higher total protein concentration in ventricular CSF (p = 0.047). Compared to patients without surgical complications, patients with complications had a significantly lower CSF/blood glucose ratio in ventricular CSF (p = 0.032). The lumbar CSF parameters had no significant differences between these groups. The changes in lumbar CSF indices over time after shunt placement were also analyzed. After shunt placement, total protein concentration was transiently increased, white blood cell count, CSF/blood glucose ratio and chloride ion concentration were continued at the preoperative level until two months after shunting surgery. These findings suggest that the composition of ventricular CSF differs from that of lumbar CSF, and different CSF parameters have disparate rostro-caudal gradients in patients with Cryptococcal meningitis. Furthermore, ventricular and lumbar CSF parameters may have different clinical implications. Transient deterioration of lumbar CSF parameters after ventriculoperitoneal shunt placement may not be due to disease progression, but to change in CSF flow rate by CSF shunts.

Measuring respiratory and cardiac influences on blood and cerebrospinal fluid flow with real-time MRI

Background. A link between various pathological conditions and blood and cerebrospinal fluid (CSF) flow alterations has been suggested by numerous studies.1 The blood and CSF dynamics are influenced by many factors, such as posture,2 heart beating, and thoracic pressure changes during respiration.2,3 The blood/CSF can be estimated using phase-contrast (PC) – magnetic resonance imaging (MRI). However, the clinical cardiac-gated cine PC-MRI requires several heartbeats to form the time-resolved flow images covering the entire cardiac cycle, not allowing to assess beat-by-beat variability differences and respiratory-driven flow changes. To overcome these limitations, we recently used a real-time (RT)-PC prototype for the study of blood and CSF flow rate modulations, showing low-frequency oscillations (Mayer waves).4 With the same MRI technique, in the current study we focused on assessing the cardiac and respiratory modulations on the blood and CSF flow rates, and the effects of different respiration modes.&#x0D; Methods. Thirty healthy volunteers (21 females, median age=26 years old, age range= 19-57 years old) were examined with a 3 T scanner. RT-PC sequences (Figure 1) allowed for a quantification of the flow rates of internal carotid arteries (ICAs), internal jugular veins (IJVs), and CSF at the first cervical level. The superior sagittal sinus (SSS) was also studied in 16 subjects.5 The flow rates were estimated with a temporal resolution of 58.5 ms for the blood, and 94 ms for the CSF. Each RT-PC lasted 60 seconds and was repeated three times: while the subject breathed with free (F) breathing, at a constant rate with a normal (PN) or forced (PD) strength. The systolic, diastolic and average flow rates and their power spectral densities were computed. High and very-high frequency peaks were identified on the spectra. Frequencies associated to the identified peaks were compared to the respiratory and cardiac frequencies estimated by a thoracic band and a pulse oximeter. The area under the spectra, normalized by the flow rate variance, was computed in the respiratory and cardiac frequency ranges (0.5 Hz-wide ranges, centered on the cardiac or breathing frequency peaks, respectively).&#x0D; Results. The frequencies associated with the spectral peaks were not significantly different compared to the respiratory and cardiac frequencies, for all regions and breathing modes. The average blood flow rate and the diastolic CSF peak progressively decreased from F to PN to PD breathing, the flow rate variance remained stable, and only the ICAs cross-sectional area decreased. The respiratory modulation increased with PD breathing compared with F and PN, while the cardiac modulations were less predominant for all the structures of interest.&#x0D; Conclusions. Using the RT-PC sequence we showed that the blood and CSF flow rates were modulated at the respiratory and cardiac frequencies. The observed reduced blood flow rate during forced breathing in the arteries and consequently in the extra and intracranial veins are suggestive of compensatory vasoconstriction in response to decreased CO2 blood concentration. Breathing modulation of flow rates was observed both in the extracranial and intracranial compartments, and it was greater during forced breathing than free breathing, due to the greater thoracic pump effect on the flow rates.

A Clinical Study on the Treatment of Recurrent Chiari (Type I) Malformation with Syringomyelia Based on the Dynamics of Cerebrospinal Fluid.

Objective Combining the dynamics of cerebrospinal fluid, our study investigates the clinical effects of syringomyelia after the combination of fourth ventricle-subarachnoid shunt (FVSS) for recurrent Chiari (type I) malformations after cranial fossa decompression (foramen magnum decompression (FMD)). Methods From December 2018 to December 2020, 15 patients with recurrent syringomyelia following posterior fossa decompression had FVSS surgery. Before and after the procedure, the clinical and imaging data of these individuals were retrospectively examined. Results Following FVSS, none of the 15 patients experienced infection, nerve injury, shunt loss, or obstruction. 13 patients improved dramatically after surgery, while 2 patients improved significantly in the early postoperative period, but the primary symptoms returned 2 months later. The Japanese Orthopedic Association (JOA) score was 12.67 ± 3.95, which was considerably better than preoperatively (t = 3.69, P0.001). The MRI results revealed that the cavities in 13 patients were reduced by at least 50% compared to the cavities measured preoperatively. The shrinkage rate of syringomyelia was 86.67% (13/15). One patient's cavities nearly vanished following syringomyelia. The size of the cavity in the patient remain unchanged, and the cavity's maximal diameter was significantly smaller than the size measured preoperatively (P < 0.001) PC-MRI results indicated that the peak flow rate of cerebrospinal fluid at the central segment of the midbrain aqueduct and the foramen magnum in patients during systole and diastole were significantly reduced after surgery (P < 0.05). Conclusion After posterior fossa decompression, FVSS can effectively restore the smooth circulation of cerebrospinal fluid and alleviate clinical symptoms in patients with recurrent Chiari (type I) malformation and syringomyelia. It is a highly effective way of treatment.

Partial Obstruction of Ventricular Catheters Affects Performance in a New Catheter Obstruction Model of Hydrocephalus.

Objective: One of the major causes of cerebral ventricular shunt failure is proximal catheter occlusion. We describe a novel ventricular cerebrospinal fluid (CSF) flow replicating system that assesses pressure and flow responses to varying degrees of catheter occlusion. Methods: Ventricular catheter performance was assessed during conditions of partial and complete occlusion. The catheters were placed into a three-dimensionally-printed phantom ventricular replicating system. Artificial CSF was pumped through the ventricular system at a constant rate of 1 mL/min to mimic CSF flow, with the proximal end of the catheter in the phantom ventricle. Pressure transducer and flow rate sensors were used to measure intra-phantom pressure, outflow pressure, and CSF flow rates. The catheters were also inserted into silicone tubing and pressure was measured in the same manner for comparison with the phantom. Results: Pressure measured in the ventricle phantom did not change when the outflow of the ventricular catheter was partially occluded. However, the intraventricular phantom pressure significantly increased when the outflow catheter was 100% occluded. The flow through the catheter showed no significant difference in rate with any degree of partial occlusion of the catheter. At the distal end of the partially occluded catheters, there was less pressure compared with the nonoccluded catheters. This difference in pressure in partially occluded catheters correlated with the percentage of catheter hole occlusion. Conclusions: Our model mimics the physiological dynamics of the CSF flow in partially and completely obstructed ventricular catheters. We found that partial occlusion of the catheter had no effect on the CSF flow rate, but did reduce outflow pressure from the catheter.

A one-dimensional model for the pulsating flow of cerebrospinal fluid in the spinal canal.

The monitoring of intracranial pressure (ICP) fluctuations, which is needed in the context of a number of neurological diseases, requires the insertion of pressure sensors, an invasive procedure with considerable risk factors. Intracranial pressure fluctuations drive the wave-like pulsatile motion of cerebrospinal fluid (CSF) along the compliant spinal canal. Systematically derived simplified models relating the ICP fluctuations with the resulting CSF flow rate can be useful in enabling indirect evaluations of the former from non-invasive magnetic resonance imaging (MRI) measurements of the latter. As a preliminary step in enabling these predictive efforts, a model is developed here for the pulsating viscous motion of CSF in the spinal canal, assumed to be a linearly elastic compliant tube of slowly varying section, with a Darcy pressure-loss term included to model the fluid resistance introduced by the trabeculae, which are thin collagen-reinforced columns that form a web-like structure stretching across the spinal canal. Use of Fourier-series expansions enables predictions of CSF flow rate for realistic anharmonic ICP fluctuations. The flow rate predicted using a representative ICP waveform together with a realistic canal anatomy is seen to compare favourably with in vivo phase-contrast MRI measurements at multiple sections along the spinal canal. The results indicate that the proposed model, involving a limited number of parameters, can serve as a basis for future quantitative analyses targeting predictions of ICP temporal fluctuations based on MRI measurements of spinal-canal anatomy and CSF flow rate.

CT Image under Improved Fuzzy C-Means Clustering Algorithm for Evaluation of the Relationship between Cerebrospinal Fluid Change and Communicating Hydrocephalus after Decompressive Craniectomy in Patients with Traumatic Brain Injury

This study was aimed to realize the automatic segmentation of communicating hydrocephalus lesions in brain CT after decompressive craniotomy (DC) in patients with traumatic brain injury (TBI) and discover correlation between cerebrospinal fluid changes and communicating hydrocephalus. Based on the traditional fuzzy C-means (FCM) algorithm, a new segmentation method filter-based FCM (FBFCM) algorithm was proposed. With 56 TBI patients as the research objects, the hydrocephalus lesions in CT images of patients after DC were segmented. The segmentation success rate (SSR), the segmentation coefficient Epc, the segmentation entropy Epe, and the number of iterations were indicators reflecting segmentation performance of FBFCM. The region of interest (ROI) on the segmented image was used to study the patient’s cerebral aqueduct, foramen magnum, and C2 level of the cerebrospinal fluid velocity and flow, to analyze the characteristics of the occurrence of communicative hydrocephalus. It was indicated that average Epc of FBFCM algorithm was 0.9321 ± 0.0144, Epe was 0.1126 ± 0.0081, the average number of iterations was 14.42 ± 3.79, and the segmentation success rate was 96%. Moreover, the above four indicators had statistically considerable differences compared with those of the FCM algorithm and the hard clustering algorithm (HCM) ( P &lt; 0.05). Analysis of the cerebrospinal fluid flow rate in patients with communicative hydrocephalus found that the cerebrospinal fluid flow rate at the midbrain aqueduct of the patient increased greatly. The net flow was 0.000 ± 0.004 mL/s in the aqueduct of the midbrain, 0.001 ± 0.006 mL/s in the foramen magnum, and 0.002 ± 0.004 mL/s in the C2 layer. In summary, the FBFCM algorithm is effective in the segmentation and processing of CT images, which can further improve the effect of this diagnosis. After examination, it is concluded that the cranial cerebrospinal fluid flow rate and flow of TBI patients are improved after DC treatment, so that the patient’s condition can be effectively relieved. It has promotion value with clinical application.

Neural Network Segmentation Algorithm-Based Magnetic Resonance Imaging to Explore the Relationship between Cerebrospinal Fluid Flow with Communicating Hydrocephalus after Decompressive Craniectomy for Craniocerebral Injury

This study aimed to explore the application value of magnetic resonance imaging optimized by neural network segmentation algorithm in analyzing the relationship between cerebrospinal fluid changes after decompressive craniectomy and the occurrence of communicating hydrocephalus. 100 patients with craniocerebral injury undergoing decompressive craniectomy in hospital were selected as research subjects. The collected MRI images were processed using the OTSU algorithm, the cerebrospinal fluid flow rate was calculated based on the observation results, and the MRI based on the neural network segmentation algorithm was used to analyze the relationship between the occurrence of communicating hydrocephalus with the cerebrospinal fluid flow after decompressive craniectomy for craniocerebral injury. Additionally, the dynamics of the flow of cerebrospinal fluid in the midbrain aqueduct was analyzed. After decompressive craniectomy for craniocerebral injury, of the 24 cases of cerebrospinal fluid accumulation, 23 cases had hydrocephalus; of the 55 cases of cerebrospinal fluid flow disorder, hydrocephalus occurred in 47 cases; and of the 21 cases of normal cerebrospinal fluid, no patients had hydrocephalus. For patients with communicating hydrocephalus, the cerebrospinal fluid flow at the aqueduct was obviously accelerated and the flow was increased. From this, the differential diagnosis of cerebrospinal fluid and communicating hydrocephalus can be further confirmed. The results showed that the third ventricle of the study group was significantly reduced, and the flow of cerebrospinal fluid was similar to that of normal people. It suggested that decompressive craniectomy can relieve communicating hydrocephalus. In patients with communicating hydrocephalus, the cerebrospinal fluid flow at the aqueduct was significantly accelerated, the flow amount was increased, and the blocked flow of cerebrospinal fluid can also lead to hydrocephalus, which further clarified the relationship between the occurrence of communicating hydrocephalus with the flow of cerebrospinal fluid. In short, the neural network segmentation algorithm-based magnetic resonance imaging demonstrated a good value in the analysis of craniocerebral injury, from which the doctor observed that the cerebrospinal fluid flow at the aqueduct was significantly accelerated. Its detection of brain complications after decompressive craniectomy was also effective.

Ventriculoperitoneal Shunt Drainage Increases With Gravity and Cerebrospinal Fluid Pressure Pulsations: Benchtop Model.

There have been few improvements in cerebrospinal fluid (CSF) shunt technology since John Holter introduced the silicon valve, with overdrainage remaining a major source of complications. To better understand why valves are afflicted by supra-normal CSF flow rates. We present in Vitro benchtop analyses of flow through a differential pressure valve under simulated physiological conditions. The pseudo-ventricle benchtop valve testing platform that comprises a rigid pseudo-ventricle, compliance chamber, pulsation generator, and pressure sensors was used to measure flow rates through a differential pressure shunt valve under the following simulated physiological conditions: orientation (horizontal/vertical), compliance (low/medium/high), and pulsation generator force (low/medium/high). Our data show that pulse pressures are faithfully transmitted from the ventricle to the valve, that lower compliance and higher pulse generator forces lead to higher pulse pressures in the pseudo-ventricle, and that both gravity and higher pulse pressure lead to higher flow rates. The presence of a valve mitigates but does not eliminate these higher flow rates. Shunt valves are prone to gravity-dependent overdrainage, which has motivated the development of gravitational valves and antisiphon devices. This study shows that overdrainage is not limited to the vertical position but that pulse pressures that simulate rhythmic (eg, cardiac) and provoked (eg, Valsalva) physiological CSF pulsations increase outflow in both the horizontal and vertical positions and are dependent on compliance. A deeper understanding of the physiological parameters that affect intracranial pressure and flow through shunt systems is prerequisite to the development of novel valves.

Optimization of a Thermal Flow Meter for Failure Management of the Shunt in Pediatric Hydrocephalus Patients.

Hydrocephalus patients suffer from an abnormal buildup of cerebrospinal fluid (CSF) in their ventricles, and there is currently no known way to cure hydrocephalus. The most prevalent treatment for managing hydrocephalus is to implant a ventriculoperitoneal shunt, which diverts excess CSF out of the brain. However, shunts are prone to failure, resulting in vague symptoms. Our patient survey results found that the lack of specificity of symptoms complicates the management of hydrocephalus in the pediatric population. The consequences include persistent mental burden on caretakers and a significant amount of unnecessary utilization of emergency healthcare resources due to the false-positive judgement of shunt failure. In order to reliably monitor shunt failures for hydrocephalus patients and their caretakers, we propose an optimized design of the thermal flow meter for precise measurements of the CSF flow rate in the shunt. The design is an implantable device which slides onto the shunt and utilizes sinusoidal heating and temperature measurements to improve the signal-to-noise ratio of flow-rate measurements by orders of magnitude.Clinical Relevance- An implantable flow meter would be transformative to allow hydrocephalus patients to monitor their shunt function at home, resulting in reduced hospital visits, reduced exposure to radiation typically required to rule out shunt failure, and reduced caretaker anxiety.

Head-nodding: a driving force for the circulation of cerebrospinal fluid

The myodural bridge (MDB) is a dense connective tissue bridge connecting the suboccipital muscles to the spinal dura mater, and it has been proven to be a normal common existing structure in humans and mammals. Some scholars believe that the suboccipital muscles can serve as a dynamic cerebrospinal fluid (CSF) pump via the MDB, and they found head rotations promote the CSF flow in human body, which provided evidence for this hypothesis. Head movement is a complex motion, but the effects of other forms of head movement on CSF circulation are less known. The present study explored the effects of head-nodding on CSF circulation. The CSF flow of 60 healthy volunteers was analyzed via cine phase-contrast magnetic resonance imaging at the level of the occipitocervical junction before and after one-minute-head-nodding period. Furthermore, the CSF pressures of 100 volunteers were measured via lumbar puncture before and after 5 times head-nodding during their anesthetizing for surgical preparation. As a result, it was found that the maximum and average CSF flow rates at the level of the upper border of atlas during ventricular diastole were significantly decreased from 1.965 ± 0.531 to 1.839 ± 0.460 ml/s and from 0.702 ± 0.253 to 0.606 ± 0.228 ml/s respectively. In the meantime, the changes in the ratio of cranial and caudal orientation of the net flow volume were found differed significantly after the one-minute-head-nodding period (p = 0.017). And on the other hand, the CSF pressures at the L3–L4 level were markedly increased 116.03 ± 26.13 to 124.64 ± 26.18 mmH2O. In conclusion, the head-nodding has obvious effects on CSF circulation and head movement is one of the important drivers of cerebrospinal fluid circulation. We propose that the suboccipital muscles, participating in various head movements, might pull the dura sac via the myodural bridge, and thus, head movement provides power for the CSF circulation.

Cerebrospinal Fluid Flow Dynamics during Handgrip Exercise in Young Healthy Adults: An MRI Study

Cerebral blood flow (CBF) increases during exercise, but its impact on cerebrospinal fluid (CSF) flow remains unknown. This study investigated CBF and CSF flow dynamics during moderate-intensity rhythmic handgrip (RHG) exercise in young healthy men and women. Twenty-six participants (12 women) underwent the RHG and resting control conditions in random order. Participants performed 3 sets of RHG, during which CINE phase-contrast magnetic resonance imaging (PC-MRI) was performed to measure blood stroke volume (SV) and flow rate in the internal carotid (ICA) and vertebral (VA) arteries, the internal jugular vein (IJV), the superior sagittal (SSS) and straight sinuses (SRS), and CSF SV and flow rate in the cerebral aqueduct of Sylvius. Blood pressure, end-tidal CO2 (EtCO2), heart rate (HR), and respiratory rate were simultaneously measured during CINE PC-MRI scans. Compared with control conditions, RHG showed significant elevations of HR, mean arterial pressure, and respiratory rate with a mild reduction of EtCO2 (all P<0.05). RHG decreased blood SV in the measured arteries, veins, and sinuses and CSF SV in the aqueduct (all P<0.05). Conversely, RHG increased blood flow in the ICA, VA, and IJV (all P<0.05). At the aqueduct, RHG decreased the absolute CSF flow rate (P=0.031), which was calculated as a sum of the caudal and cranial CSF flow rates. Change in the ICA SV was positively correlated with changes in the IJV, SSS, SRS, and aqueductal SV during RHG (all P<0.05). These findings demonstrate a close coupling between the CBF and CSF flow dynamics during moderate-intensity RHG exercise in young healthy adults.