Cerebrospinal Fluid Volume Changes Research Articles

Anesthesia Blunts Carbon Dioxide Effects on Glymphatic Cerebrospinal Fluid Dynamics in Mechanically Ventilated Rats.

Impaired glymphatic clearance of cerebral metabolic products and fluids contribute to traumatic and ischemic brain edema and neurodegeneration in preclinical models. Glymphatic perivascular cerebrospinal fluid flow varies between anesthetics possibly due to changes in vasomotor tone and thereby in the dynamics of the periarterial cerebrospinal fluid (CSF)-containing space. To better understand the influence of anesthetics and carbon dioxide levels on CSF dynamics, this study examined the effect of periarterial size modulation on CSF distribution by changing blood carbon dioxide levels and anesthetic regimens with opposing vasomotor influences: vasoconstrictive ketamine-dexmedetomidine (K/DEX) and vasodilatory isoflurane. End-tidal carbon dioxide (ETco2) was modulated with either supplemental inhaled carbon dioxide to reach hypercapnia (Etco2, 80 mmHg) or hyperventilation (Etco2, 20 mmHg) in tracheostomized and anesthetized female rats. Distribution of intracisternally infused radiolabeled CSF tracer 111In-diethylamine pentaacetate was assessed for 86 min in (1) normoventilated (Etco2, 40 mmHg) K/DEX; (2) normoventilated isoflurane; (3) hypercapnic K/DEX; and (4) hyperventilated isoflurane groups using dynamic whole-body single-photon emission tomography. CSF volume changes were assessed with magnetic resonance imaging. Under normoventilation, cortical CSF tracer perfusion, perivascular space size around middle cerebral arteries, and intracranial CSF volume were higher under K/DEX compared with isoflurane (cortical maximum percentage of injected dose ratio, 2.33 [95% CI, 1.35 to 4.04]; perivascular size ratio 2.20 [95% CI, 1.09 to 4.45]; and intracranial CSF volume ratio, 1.90 [95% CI, 1.33 to 2.71]). Under isoflurane, tracer was directed to systemic circulation. Under K/DEX, the intracranial tracer distribution and CSF volume were uninfluenced by hypercapnia compared with normoventilation. Intracranial CSF tracer distribution was unaffected by hyperventilation under isoflurane despite a 28% increase in CSF volume around middle cerebral arteries. K/DEX and isoflurane overrode carbon dioxide as a regulator of CSF flow. K/DEX could be used to preserve CSF space and dynamics in hypercapnia, whereas hyperventilation was insufficient to increase cerebral CSF perfusion under isoflurane.

Analysis of brain edema in RHAPSODY.

Cerebral edema is a secondary complication of acute ischemic stroke, but its time course and imaging markers are not fully understood. Recently, net water uptake (NWU) has been proposed as a novel marker of edema. Studying the RHAPSODY trial cohort, we sought to characterize the time course of edema and test the hypothesis that NWU provides distinct information when added to traditional markers of cerebral edema after stroke by examining its association with other markers. A total of 65 patients had measurable supratentorial ischemic lesions. Patients underwent head computed tomography (CT), brain magnetic resonance imaging (MRI) scans, or both at the baseline visit and after 2, 7, 30, and 90 days following enrollment. CT and MRI scans were used to measure four imaging markers of edema: midline shift (MLS), hemisphere volume ratio (HVR), cerebrospinal fluid (CSF) volume, and NWU using semi-quantitative threshold analysis. Trajectories of the markers were summarized, as available. Correlations of the markers of edema were computed and the markers compared by clinical outcome. Regression models were used to examine the effect of 3K3A-activated protein C (APC) treatment. Two measures of mass effect, MLS and HVR, could be measured on all imaging modalities, and had values available across all time points. Accordingly, mass effect reached a maximum level by day 7, normalized by day 30, and then reversed by day 90 for both measures. In the first 2 days after stroke, the change in CSF volume was associated with MLS (ρ = -0.57, p = 0.0001) and HVR (ρ = -0.66, p < 0.0001). In contrast, the change in NWU was not associated with the other imaging markers (all p ⩾ 0.49). While being directionally consistent, we did not observe a difference in the edema markers by clinical outcome. In addition, baseline stroke volume was associated with all markers (MLS (p < 0.001), HVR (p < 0.001), change in CSF volume (p = 0.003)) with the exception of NWU (p = 0.5). Exploratory analysis did not reveal a difference in cerebral edema markers by treatment arm. Existing cerebral edema imaging markers potentially describe two distinct processes, including lesional water concentration (i.e. NWU) and mass effect (MLS, HVR, and CSF volume). These two types of imaging markers may represent distinct aspects of cerebral edema, which could be useful for future trials targeting this process.

Effect of antisiphon devices on ventriculoperitoneal shunt drainage dynamics in growing children.

Infants and small children face changing boundary conditions when treated with a ventriculoperitoneal shunt (VPS) for hydrocephalus. There are no systematic data describing shunt drainage behavior and changes over time in a growing child. Using a child-adapted patient simulator, the authors investigated the drainage behaviors of fixed differential pressure (DP) valves and adjustable valves with devices for preventing overdrainage in children of different ages. Three miniNAV DP valves with a 10-cm H2O medium-pressure setting (MN10) and three adjustable proGAV2.0 valves with a 25-cm H2O gravitational unit (GU) at low 5-cm H2O opening pressure (PG5) and medium 10-cm H2O opening pressure (PG10) settings were each investigated with a hardware-in-the-loop test bed. This test bed consisted of a posture motion mechanism and two pressure compartments that mimicked intracranial and abdominal pressures and was used to test the VPS under realistic in vitro conditions. Body orientation and length were physically set according to the child's age. The software simulated the physiological situations of children aged 1, 5, and 10 years. All valves were tested according to these specifications, with 5 runs for 1 hour each in the horizontal, vertical, and horizontal positions. Intracranial pressure (ICP) and VPS flow were measured, and the respective cerebrospinal fluid volume changes and ICP set value were computed. The drainage parameters increased with age in all valves in the vertical position, with that of MN10 being pronounced in the 1-year-old simulation. The GU values in PG5 and PG10 substantially reduced drainage compared with MN10. PG10 prevented drainage in the 1-year-old and 5-year-old setups, but there was some drainage at physiological ICP in the 10-year-old setup. In contrast, MN10 produced the largest decreases in ICP across all ages and positions, and overdrainage resulted in insufficient ICP recovery in the subsequent horizontal position. ICP levels were mostly constant with PG10 at all ages. This study shows that unprotected DP valves may lead to overdrainage in infants, whereas low-pressure GU valves can prevent overdrainage through 5 years and medium-pressure GU valves admit physiological ICP through at least 10 years. Therefore, devices for preventing overdrainage should be included in the first implanted shunt, and opening pressure should be adjusted as the child grows.

Assessment of disorders of hemodynamics and csf dynamics in idiopathic intracranial hypertension syndrome according to MRI data

Highlights. An increase in the pulsatility index of intracranial venous blood flow and cerebrospinal fluid flow at the foramen magnum level, and a decrease in arteriovenous delay and an intracranial compliance index indicate disturbances in the pulse wave distribution, and a decrease in compliance/extensibility of the brain due to increased intracranial pressure.Aim. To assess the parameters of hemodynamics and cerebrospinal fluid dynamics in patients with idiopathic intracranial hypertension syndrome according to phase-contrast MRI.Methods. The study included 18 patients with idiopathic intracranial hypertension syndrome and 20 controls, all patient were examined using the Ingenia 3,0T MRI scanner. The analysis was performed using phase-contrast MRI to assess quantitative parameters of hemodynamics and cerebrospinal fluid (CSF) dynamics in 14 different structures. The blood and CSF volumes, pulsatility index (PI), arterio-venous delay, and intracranial compliance index were calculated. The Mann-Whitney U-test reliability was used to assess the differences between the controls and patients.Results. The group of patients had an increased CSF systolic peak at the foramen magnum without significant changes in CSF volume, and significantly increased CSF PI at the cervical level by 11.88% (p&lt;0,05). There was a tendency toward an increase in the intracranial venous blood volume, as well as a tendency toward significant increase in PI at the straight and superior sagittal sinuses by 1,3 times (p&gt;&lt;0,01, p&gt;&lt;0,05). Moreover, there was a reduction of intracranial arterio-venous delay by 1,9 times (p&gt;&lt;0,05), and a significant decrease in the intracranial compliance index by 1,2 times (p&gt;&lt;0,05). Conclusion We have assessed the parameters of hemodynamics and CSF dynamics in patients with idiopathic intracranial hypertension and revealed disturbances in CSF dynamics and pulse wave propagation in the intracranial regions. Such changes may indicate a decrease in compliance/increase in stiffness of the brain tissue due to an increase in intracranial pressure and a possible diffuse stagnation of interstitial fluid. Keywords Phase-contrast magnetic resonance imaging • Central nervous system • Idiopathic intracranial hypertension • Hemodynamics • Cerebrospinal fluid dynamics • Intracranial compliance index&gt;˂0,05). There was a tendency toward an increase in the intracranial venous blood volume, as well as a tendency toward significant increase in PI at the straight and superior sagittal sinuses by 1,3 times (p˂0,01, p˂0,05). Moreover, there was a reduction of intracranial arterio-venous delay by 1,9 times (p˂0,05), and a significant decrease in the intracranial compliance index by 1,2 times (p˂0,05).Conclusion. We have assessed the parameters of hemodynamics and CSF dynamics in patients with idiopathic intracranial hypertension and revealed disturbances in CSF dynamics and pulse wave propagation in the intracranial regions. Such changes may indicate a decrease in compliance/increase in stiffness of the brain tissue due to an increase in intracranial pressure and a possible diffuse stagnation of interstitial fluid.

Boundary conditions investigation to improve computer simulation of cerebrospinal fluid dynamics in hydrocephalus patients

Three-D head geometrical models of eight healthy subjects and 11 hydrocephalus patients were built using their CINE phase-contrast MRI data and used for computer simulations under three different inlet/outlet boundary conditions (BCs). The maximum cerebrospinal fluid (CSF) pressure and the ventricular system volume were more effective and accurate than the other parameters in evaluating the patients’ conditions. In constant CSF pressure, the computational patient models were 18.5% more sensitive to CSF volume changes in the ventricular system under BC “C”. Pulsatile CSF flow rate diagrams were used for inlet and outlet BCs of BC “C”. BC “C” was suggested to evaluate the intracranial compliance of the hydrocephalus patients. The results suggested using the computational fluid dynamic (CFD) method and the fully coupled fluid-structure interaction (FSI) method for the CSF dynamic analysis in patients with external and internal hydrocephalus, respectively.

Progressive Ventricles Enlargement and Cerebrospinal Fluid Volume Increases as a Marker of Neurodegeneration in Patients with Spinal Cord Injury: A Longitudinal Magnetic Resonance Imaging Study.

Next to gray and white matter atrophy, cerebrospinal fluid (CSF) volume and ventricular dilation may be surrogate biomarkers for brain atrophy in spinal cord injury (SCI). We therefore aimed to track brain atrophy by means of CSF volume changes and ventricular enlargements over two years after SCI. Fifteen patients with SCI and 18 healthy controls underwent a series of T1-weighted scans during five time points over two years. Changes of CSF/intracranial volume (CSF/ICV) ratio, CSF volume, and ventricular enlargement rate over time were determined. Sample sizes with 80% power and 5% significance were calculated to detect a range of treatment effects for a two-armed trial. There was a significant cross-sectional increased CSF/ICV ratio in patients compared with controls at each time point (p < 0.02). The rate of CSF/ICV changes, however, was not significantly different between groups over time. CSF volume increased linearly over bilateral sensorimotor cortices (left: p = 0.002, right: p = 0.042) and in the supracerebellar space (p < 0.001) within two years. An acceleration of the enlargement within the third (p = 0.017) and the fourth (p = 0.006) ventricles was observed in patients over time. Sample size estimation for six-month trials with CSF volume requires 25 patients per treatment arm to detect a hypothetical treatment effect in terms of slowing of atrophy rate of 30%. This study shows that SCI-induced changes in CSF/ICV ratio and ventricular expansion rate provide additional information on the neurodegenerative processes after injury. The sensitivity to scoring treatment effects speaks to its potential to serve as a sensitive biomarker in addition to local atrophy measures.

Lumbosacral and thoracolumbosacral cerebrospinal fluid volume changes in neonates, infants, children, and adolescents: A retrospective magnetic resonance imaging study.

The volume of cerebrospinal fluid can affect the pharmacokinetics and pharmacodynamics of local anesthetics for spinal anesthesia and other intrathecal medications. The objective of this study was to estimate the lumbosacral cerebrospinal fluid volume and thoracolumbosacral cerebrospinal fluid volume using magnetic resonance images in pediatric patients from neonates and infants to adolescents. Spinal magnetic resonance images of 500 pediatric patients (age <18years) were reviewed. The lumbosacral cerebrospinal fluid volumes of 418 patients and thoracolumbosacral cerebrospinal fluid volumes of 248 patients were measured. The relationship between cerebrospinal fluid volumes and age, height, and weight were evaluated. The lumbosacral and thoracolumbosacral cerebrospinal fluid volumes per weight were calculated to elucidate developmental changes. The lumbosacral and thoracolumbosacral cerebrospinal fluid volumes showed linear correlations with height (r2 =0.730 and r2 =0.661, respectively), whereas they showed curvilinear correlations with age (r2 =0.752 and r2 =0.717, respectively) and weight (r2 =0.734 and r2 =0.734, respectively). The mean lumbosacral cerebrospinal fluid volume per weight (mL/kg) was 0.85 (standard deviation [SD]: 0.19, 95% confidence interval [CI]: 0.81-0.90) in neonates and infants, 0.86 (SD: 0.22, 95% CI: 0.83-0.89) in toddlers and preschoolers, 0.71 (SD: 0.26, 95% CI: 0.66-0.76) in schoolers, and 0.54 (SD: 0.20, 95% CI: 0.49-0.60) in adolescents. The mean thoracolumbosacral cerebrospinal fluid volume per weight (mL/kg) was 1.95 (SD: 0.37, 95% CI: 1.86-2.04) in neonates and infants, 1.82 (SD: 0.41, 95% CI: 1.75-1.88) in toddlers and preschoolers, 1.38 (SD: 0.40, 95% CI: 1.23-1.52) in schoolers, and 0.99 (SD: 0.34, 95% CI: 0.45-1.53) in adolescents. The lumbosacral and thoracolumbosacral cerebrospinal fluid volumes in pediatric patients were much smaller than previously presented values, showing linear correlations with height, and demonstrate curvilinear correlations with age and weight.

Apparent diffusion coefficient changes in human brain during sleep – Does it inform on the existence of a glymphatic system?

The role of sleep in brain physiology is poorly understood. Recently rodent studies have shown that the glymphatic system clears waste products from brain more efficiently during sleep compared to wakefulness due to the expansion of the interstitial fluid space facilitating entry of cerebrospinal fluid (CSF) into the brain. Here, we studied water diffusivity in the brain during sleep and awake conditions, hypothesizing that an increase in water diffusivity during sleep would occur concomitantly with an expansion of CSF volume - an effect that we predicted based on preclinical findings would be most prominent in cerebellum. We used MRI to measure slow and fast components of the apparent diffusion coefficient (ADC) of water in the brain in 50 healthy participants, in 30 of whom we compared awake versus sleep conditions and in 20 of whom we compared rested-wakefulness versus wakefulness following one night of sleep-deprivation. Sleep compared to wakefulness was associated with increases in slow-ADC in cerebellum and left temporal pole and with decreases in fast-ADC in thalamus, insula, parahippocampus and striatal regions, and the density of sleep arousals was inversely associated with ADC changes. The CSF volume was also increased during sleep and was associated with sleep-induced changes in ADCs in cerebellum. There were no differences in ADCs with wakefulness following sleep deprivation compared to rested-wakefulness. Although we hypothesized increases in ADC with sleep, our findings uncovered both increases in slow ADC (mostly in cerebellum) as well as decreases in fast ADC, which could reflect the distinct biological significance of fast- and slow-ADC values in relation to sleep. While preliminary, our findings suggest a more complex sleep-related glymphatic function in the human brain compared to rodents. On the other hand, our findings of sleep-induced changes in CSF volume provide preliminary evidence that is consistent with a glymphatic transport process in the human brain.

New Insight into the Mechanism of Mannitol Effects on Cerebrospinal Fluid Pressure Decrease and Craniospinal Fluid Redistribution

Intracranial hypertension, which often follows a severe brain injury, is usually treated with intravenous (i.v.) application of hyperosmolar solutions. The mechanism of intracranial cerebrospinal fluid (CSF) pressure decrease after such a treatment is still unclear. The aim of this article was to try to explain the mechanism of CSF pressure reduction after i.v. hyperosmolar mannitol bolus in regard to the changes in CSF volume. Two types of experiments were done on anesthetized cats before and after hyperosmolar mannitol application: ventriculo-cisternal perfusion at different perfusion rates, simultaneously measuring the perfusate outflow volume, and CSF pressure recording in the lateral ventricle before and during artificial CSF infusion. Mannitol application in the first group of cats significantly reduced collected prefusate volume during ventriculo-cisternal perfusion, and in the second group it prevented CSF pressure increase caused by artificial CSF infusion. Our results strongly suggest that the mechanism of hyperosmolar mannitol action after its i.v. application is based on osmotic fluid retrieval from interstitial and cerebrospinal compartments into the microvessels. This shift, without significant volume change inside the cranium, causes a predominant decrease of CSF volume in the spinal part of the system, which in turn leads to lowering of the CSF pressure. Spinal CSF volume decrease is enabled by the extensibility of the spinal dura, this way providing the possibility for CSF volume redistribution inside the CSF system, together with CSF pressure decrease. This mechanism of mannitol action is in accordance with the new hypothesis of CSF physiology.

Osmotic Shifts, Cerebral Edema, and Neurologic Deterioration in Severe Hepatic Encephalopathy.

We sought to determine the effect of acute electrolyte and osmolar shifts on brain volume and neurologic function in patients with liver failure and severe hepatic encephalopathy. Retrospective analysis of brain CT scans and clinical data. Tertiary care hospital ICUs. Patients with acute or acute-on-chronic liver failure and severe hepatic encephalopathy. Clinically indicated CT scans and serum laboratory studies. Change in intracranial cerebrospinal fluid volume between sequential CT scans was measured as a biomarker of acute brain volume change. Corresponding changes in serum osmolality, chemistry measurements, and Glasgow Coma Scale were determined. Associations with cerebrospinal fluid volume change and Glasgow Coma Scale change for initial volume change assessments were identified by Spearman's correlations (rs) and regression models. Consistency of associations with repeated assessments was evaluated using generalized estimating equations. Forty patients were included. Median baseline osmolality was elevated (310 mOsm/Kg [296-321 mOsm/Kg]) whereas sodium was normal (137 mEq/L [134-142 mEq/L]). Median initial osmolality change was 9 mOsm/kg (5-17 mOsm/kg). Neuroimaging consistent with increased brain volume occurred in 27 initial assessments (68%). Cerebrospinal fluid volume change was more strongly correlated with osmolality (r = 0.70; p = 4 × 10) than sodium (r = 0.28; p = 0.08) change. Osmolality change was independently associated with Glasgow Coma Scale change (p = 1 × 10) and cerebrospinal fluid volume change (p = 2.7 × 10) in initial assessments and in generalized estimating equations using all 103 available assessments. Acute decline in osmolality was associated with brain swelling and neurologic deterioration in severe hepatic encephalopathy. Minimizing osmolality decline may avoid neurologic deterioration.

ICP Monitoring and Phase-Contrast MRI to Investigate Intracranial Compliance.

The amplitude of intracranial pressure (ICP) can be measured by ICP monitoring. Phase-contrast magnetic resonance imaging (PCMRI) can quantify blood and cerebrospinal fluid (CSF) flows. The aim of this work was to investigate intracranial compliance at rest by combining baseline ICP monitoring and PCMRI in hydrocephalus patients. ICP monitoring was performed before infusion testing to quantify ΔICP_rest at the basal condition in 33 suspected hydrocephalus patients (74 years). The day before, patients had had a PCMRI to assess total cerebral blood flow (tCBF), intracranial blood volume change (stroke volume SVblood), and cervical CSF volume change (the stroke volume CSV). Global (blood and CSF) intracranial volume change (ΔIVC) during each cardiac cycle (CC) was calculated. Finally, Compliance: C_rest = ΔIVC/ΔICP_rest was calculated. The data set was postprocessed by two operators according to blind analysis. Bland-Altman plots showed that measurements presented no significant difference between the two operators. ΔICP_rest = 2.41 ± 1.21 mmHg, tCBF = 469.89 ± 127.54 mL/min, SVblood = 0.82 ± 0.32 mL/cc, CSV = 0.50 ± 0.22 mL/cc, ΔIVC = 0.44 ± 0.22 mL, and C_rest = 0.23 ± 0.15 mL/mmHg. There are significant relations between SVblood and CSV and also SVblood and tCBF. During "basal" condition, the compliance amplitude of the intracranial compartment is heterogeneous in suspected hydrocephalus patients, and its value is lower than expected! This new parameter could represent new information, complementary to conventional infusion tests. We hope that this information can be applied to improve the selection of patients for shunt surgery.

Intracranial volumetric changes govern cerebrospinal fluid flow in the Aqueduct of Sylvius in healthy adults

Purpose: To characterize the intracranial volumetric changes that influence the cerebrospinal fluid (CSF) pulse in the Aqueduct of Sylvius (AoS). Materials and Methods: Neck MRI data were acquired from 12 healthy adults (8 female and 4 males; mean age=30.9 years), using a 1.5 Tesla scanner. The intracranial arterial, venous and CSF volumes changes, together with the aqueductal CSF (aCSF) volume, were estimated from flow rate data acquired at C2/C3 level and in the AoS. The correlations and temporal relationships among these volumes were computed. Results: The aCSF volumetric changes were strongly correlated (r = 0.967, p<0.001) with the changes in intracranial venous volume, whose peak occurred 7.0% of cardiac cycle (p = 0.023) before peak aCSF volume, but less correlated with the intracranial arterial and CSF volume changes (r=-0.664 and 0.676 respectively, p<0.001). The intracranial CSF volume change was correlated with the intracranial venous volume change (r=0.820, p<0.001), whose peak occurred slightly before (4.2% of CC, p=0.059). Conclusion: The aCSF pulse is strongly correlated with intracranial venous volume, with expansion of the cortical veins occurring prior to aCSF flow towards the third ventricle. Both caudal-cranial aCSF flow and venous blood retention occur when arterial blood volume is at a minimum.

Changes in the cerebrospinal fluid circulatory system of the developing rat: quantitative volumetric analysis and effect on blood-CSF permeability interpretation.

BackgroundThe cerebrospinal fluid (CSF) circulatory system is involved in neuroimmune regulation, cerebral detoxification, and delivery of various endogenous and exogenous substances. In conjunction with the choroid plexuses, which form the main barrier site between blood and CSF, this fluid participates in controlling the environment of the developing brain. The lack of comprehensive data on developmental changes in CSF volume and distribution impairs our understanding of CSF contribution to brain development, and limits the interpretation of blood-CSF permeability data. To address these issues, we describe the evolution of the CSF circulatory system during the perinatal period and have quantified the volume of the different ventricular, cisternal and subarachnoid CSF compartments at three ages in developing rats.MethodsImmunohistofluorescence was used to visualize tight junctions in parenchymal and meningeal vessels, and in choroid plexus epithelium of 19-day fetal rats. A quantitative method based on serial sectioning of frozen head and surface measurements at the cutting plane was used to determine the volume of twenty different CSF compartments in rat brain on embryonic day 19 (E19), and postnatal days 2 (P2) and 9 (P9). Blood-CSF permeability constants for sucrose were established at P2 and P9, following CSF sampling from the cisterna magna.ResultsClaudin-1 and claudin-5 immunohistofluorescence labeling illustrated the barrier phenotype acquired by all blood–brain and blood-CSF interfaces throughout the entire CNS in E19 rats. This should ensure that brain fluid composition is regulated and independent from plasma composition in developing brain. Analysis of the caudo-rostral profiles of CSF distribution and of the volume of twenty CSF compartments indicated that the CSF-to-cranial cavity volume ratio decreases from 30% at E19 to 10% at P9. CSF compartmentalization within the brain changes during this period, with a major decrease in CSF-to-brain volume ratio in the caudal half of the brain. Integrating CSF volume with the measurement of permeability constants, adds to our understanding of the apparent postnatal decrease in blood-CSF permeability to sucrose.ConclusionReference data on CSF compartment volumes throughout development are provided. Such data can be used to refine blood-CSF permeability constants in developing rats, and should help a better understanding of diffusion, bulk flow, and volume transmission in the developing brain.Electronic supplementary materialThe online version of this article (doi:10.1186/s12987-015-0001-2) contains supplementary material, which is available to authorized users.

3D mapping of cerebrospinal fluid local volume changes in patients with hydrocephalus treated by surgery: preliminary study

To develop automated deformation modelling for the assessment of cerebrospinal fluid (CSF) local volume changes in patients with hydrocephalus treated by surgery. Ventricular and subarachnoid CSF volume changes were mapped by calculating the Jacobian determinant of the deformation fields obtained after non-linear registration of pre- and postoperative images. A total of 31 consecutive patients, 15 with communicating hydrocephalus (CH) and 16 with non-communicating hydrocephalus (NCH), were investigated before and after surgery using a 3D SPACE (sampling perfection with application optimised contrast using different flip-angle evolution) sequence. Two readers assessed CSF volume changes using 3D colour-encoded maps. The Evans index and postoperative volume changes of the lateral ventricles and sylvian fissures were quantified and statistically compared. Before surgery, sylvian fissure and brain ventricle volume differed significantly between CH and NCH (P = 0.001 and P = 0.025, respectively). After surgery, 3D colour-encoded maps allowed for the visual recognition of the CSF volume changes in all patients. The amounts of ventricle volume loss of CH and NCH patients were not significantly different (P = 0.30), whereas readjustment of the sylvian fissure volume was conflicting in CH and NCH patients (P < 0.001). The Evans index correlated with ventricle volume in NCH patients. 3D mapping of CSF volume changes is feasible providing a quantitative follow-up of patients with hydrocephalus. • MRI can provide helpful information about cerebrospinal fluid volumes. • 3D CSF mapping allows quantitative follow-up in communicating and non-communicating hydrocephalus. • Following intervention, fissures and cisterns readjust in both forms of hydrocephalus. • These findings support the hypothesis of suprasylvian block in communicating hydrocephalus. • 3D mapping may improve shunt dysfunction detection and guide valve pressure settings.

Gestation-related Reduction in Lumbar Cerebrospinal Fluid Volume and Dural Sac Surface Area

Onuki, E.; Higuchi, H.; Takagi, S.; Nishijima, K.; Fujita, N.; Matsuura, T.; Ozaki, M. Author Information

Neocortical and hippocampal volume loss in a human ciliopathy: A quantitative MRI study in Bardet–Biedl syndrome

Cilia are ubiquitous cell surface organelles with diverse roles from embryogenesis to adult life. The neurodevelopmental functions of the cilium are currently under investigation in animal systems, but relevance to human brain development remains uncertain. We present the first systematic investigation of structural neuroanatomy in a ciliopathy-Bardet-Biedl syndrome (BBS). Qualitative and quantitative aspects of brain structure were evaluated via magnetic resonance imaging in 10 patients with BBS (ages 14-28 years). In comparison to age and gender-matched healthy controls, BBS patients had significantly reduced total gray matter (GM) volume but no total white matter (WM) or cerebrospinal fluid volume changes. Voxel-based morphometric analysis indicated regional GM volume loss bilaterally in the anterior temporal lobes and in the medial orbitofrontal cortex, and WM volume loss in the right inferior longitudinal fasciculus. Region-of-interest measurements revealed reduced volume of the hippocampus. Two patients were found to have ventriculomegaly. Global GM reduction and regional volume reductions in the temporal lobe may underlie the learning disabilities and behavioral problems experienced by some patients with BBS. These findings are consistent with previous observations in mouse models of BBS, and further implicate the cilium in neurodevelopmental processes relevant to human cognitive function.

Gestation-Related Reduction in Lumbar Cerebrospinal Fluid Volume and Dural Sac Surface Area

Facilitation of the spread of neuraxial anesthesia in pregnant women may be attributable in part to compression of the dural sac by the engorged epidural venous plexus. In this study, we used magnetic resonance imaging to examine pregnancy-induced changes in the lumbosacral cerebrospinal fluid (CSF) volume and dural sac surface area. Magnetic resonance images of 18 healthy women (mean age 29 yr, mean height 158 cm, and mean weight 58 kg) were obtained to measure lumbosacral CSF volume and dural sac surface area in the nonpregnant and pregnant states (median 36 wk gestation [31-39]) and the paired images were compared. The mean lumbosacral CSF volume and dural sac surface area in the nonpregnant state were 39.6 +/- 5.8 mL and 11.0 +/- 0.8 cm(2), respectively. Pregnancy was associated with compression of the dural sac, resulting in a significantly reduced mean CSF volume (33.2 +/- 6.2 mL) and dural sac surface area (9.9 +/- 1.0 cm(2)) in all subjects (P < 0.001). The mean change in CSF volume and dural sac surface area was 16.7% +/- 0.8% and 10.0% +/- 0.5%, respectively. Gestational week (between 31 and 39 wk) correlated significantly with the reduction in CSF volume (rho = 0.74, P < 0.001) and dural sac surface area (rho = 0.66, P < 0.01). These findings indicate an association between gestational week (Weeks 31-39) and a reduction in both CSF volume and dural sac surface area. These reductions may, at least in part, explain the facilitation of the spread of intrathecal anesthesia in pregnant women.

A model for an inverse power constitutive law for cerebral compliance

This work provides a model that links the commonly used inverse power relationship between cerebral compliance and intracranial pressure to some mechanical properties of distal cerebral veins. The underlying model of the compliance is based on a mechanism whereby the distal cerebral blood vessels are assumed to be the main compliant part of the brain and cerebrospinal fluid volume changes are accommodated by blood displacement into or out of these vessels. This simplified model is not intended to produce a highly accurate prediction of the intracranial pressure-volume curve, which is best achieved by a numerical solution of more complicated models, but rather to justify the phenomenological inverse power law and to provide a basic interpretation of cerebral elasticity, reference pressure and exponent of the constitutive law in terms of underlying mechanical parameters.

Multiplicity of cerebrospinal fluid functions: New challenges in health and disease.

This review integrates eight aspects of cerebrospinal fluid (CSF) circulatory dynamics: formation rate, pressure, flow, volume, turnover rate, composition, recycling and reabsorption. Novel ways to modulate CSF formation emanate from recent analyses of choroid plexus transcription factors (E2F5), ion transporters (NaHCO3 cotransport), transport enzymes (isoforms of carbonic anhydrase), aquaporin 1 regulation, and plasticity of receptors for fluid-regulating neuropeptides. A greater appreciation of CSF pressure (CSFP) is being generated by fresh insights on peptidergic regulatory servomechanisms, the role of dysfunctional ependyma and circumventricular organs in causing congenital hydrocephalus, and the clinical use of algorithms to delineate CSFP waveforms for diagnostic and prognostic utility. Increasing attention focuses on CSF flow: how it impacts cerebral metabolism and hemodynamics, neural stem cell progression in the subventricular zone, and catabolite/peptide clearance from the CNS. The pathophysiological significance of changes in CSF volume is assessed from the respective viewpoints of hemodynamics (choroid plexus blood flow and pulsatility), hydrodynamics (choroidal hypo- and hypersecretion) and neuroendocrine factors (i.e., coordinated regulation by atrial natriuretic peptide, arginine vasopressin and basic fibroblast growth factor). In aging, normal pressure hydrocephalus and Alzheimer's disease, the expanding CSF space reduces the CSF turnover rate, thus compromising the CSF sink action to clear harmful metabolites (e.g., amyloid) from the CNS. Dwindling CSF dynamics greatly harms the interstitial environment of neurons. Accordingly the altered CSF composition in neurodegenerative diseases and senescence, because of adverse effects on neural processes and cognition, needs more effective clinical management. CSF recycling between subarachnoid space, brain and ventricles promotes interstitial fluid (ISF) convection with both trophic and excretory benefits. Finally, CSF reabsorption via multiple pathways (olfactory and spinal arachnoidal bulk flow) is likely complemented by fluid clearance across capillary walls (aquaporin 4) and arachnoid villi when CSFP and fluid retention are markedly elevated. A model is presented that links CSF and ISF homeostasis to coordinated fluxes of water and solutes at both the blood-CSF and blood-brain transport interfaces.Outline1 Overview2 CSF formation2.1 Transcription factors2.2 Ion transporters2.3 Enzymes that modulate transport2.4 Aquaporins or water channels2.5 Receptors for neuropeptides3 CSF pressure3.1 Servomechanism regulatory hypothesis3.2 Ontogeny of CSF pressure generation3.3 Congenital hydrocephalus and periventricular regions3.4 Brain response to elevated CSF pressure3.5 Advances in measuring CSF waveforms4 CSF flow4.1 CSF flow and brain metabolism4.2 Flow effects on fetal germinal matrix4.3 Decreasing CSF flow in aging CNS4.4 Refinement of non-invasive flow measurements5 CSF volume5.1 Hemodynamic factors5.2 Hydrodynamic factors5.3 Neuroendocrine factors6 CSF turnover rate6.1 Adverse effect of ventriculomegaly6.2 Attenuated CSF sink action7 CSF composition7.1 Kidney-like action of CP-CSF system7.2 Altered CSF biochemistry in aging and disease7.3 Importance of clearance transport7.4 Therapeutic manipulation of composition8 CSF recycling in relation to ISF dynamics8.1 CSF exchange with brain interstitium8.2 Components of ISF movement in brain8.3 Compromised ISF/CSF dynamics and amyloid retention9 CSF reabsorption9.1 Arachnoidal outflow resistance9.2 Arachnoid villi vs. olfactory drainage routes9.3 Fluid reabsorption along spinal nerves9.4 Reabsorption across capillary aquaporin channels10 Developing translationally effective models for restoring CSF balance11 Conclusion

Brain structural damage in spinocerebellar ataxia type 2. A voxel‐based morphometry study

Voxel-based morphometry (VBM) enables an unbiased in-vivo whole-brain quantitative analysis of differences in gray matter (GM), white matter (WM) and cerebro-spinal fluid (CSF) volumes. We assessed with VBM 20 spinocerebellar ataxia Type 2 (SCA2) patients with mild or moderate cerebellar deficit and 20 age and sex-matched healthy controls. SCA2 patients showed a significant (P < 0.05 corrected for multiple comparison) symmetric loss of GM in the cerebellar vermis and hemispheres sparing lobules I,II, Crus II,VII, and X, and of the WM in the peridentate region, middle cerebellar peduncles, dorsal pons, and cerebral peduncles. The CSF volume was increased in the posterior cranial fossa. No GM, WM or CSF volume changes were observed in the supratentorial compartment. A mild (P < 0.05, >0.01) correlation was observed between the GM and WM loss and severity of the neurological deficit. In SCA2 patients with mild to moderate cerebellar deficit, GM and WM volume loss and CSF volume increase are confined to the posterior cranial fossa.