ORCID Profile
0000-0003-3095-9047
Current Organisations
Royal Australian and New Zealand College of Radiologists
,
John Hunter Hospital
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Publisher: American Society of Neuroradiology (ASNR)
Date: 02-2008
DOI: 10.3174/AJNR.A0804
Publisher: Springer Science and Business Media LLC
Date: 29-09-2022
Publisher: Georg Thieme Verlag KG
Date: 04-12-2014
Abstract: The etiology of external hydrocephalus is usually ascribed to either a delay in maturation or obstruction of the arachnoid granulations, but the arachnoid granulations are absent in neonates. Venous outflow stenoses, similar to those seen in idiopathic intracranial hypertension (IIH), have been described in external hydrocephalus. A reversible collapse of the sinuses is known to operate in IIH, but collapsible sinuses have not been previously described in infants with external hydrocephalus. Three infants with external hydrocephalus had magnetic resonance venography at differing time points during their illness. The venous sinuses varied in size depending on the cerebrospinal fluid pressure similar to IIH in adults. External hydrocephalus may be analogous to IIH in adults.
Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
Date: 2007
Publisher: Springer Science and Business Media LLC
Date: 17-08-2010
Publisher: Springer Science and Business Media LLC
Date: 28-04-2015
Publisher: Elsevier BV
Date: 02-2004
Publisher: American Roentgen Ray Society
Date: 04-2002
DOI: 10.2214/AJR.178.4.1780921
Abstract: Obstructive uropathy in the early stages can be difficult to diagnose using either standard sonography or the arterial resistive index. We tested the hypothesis that acute obstruction of the renal collecting system reduces the intraparenchymal renal compliance, which affects the intraparenchymal venous blood flow to a greater degree than the arterial flow. Twelve patients with clinical evidence of acute obstructive uropathy were referred for helical CT to confirm the diagnosis and to provide a gold standard by which we could evaluate the sonographic findings in the 12 test patients. Twelve patients without renal disease served as a control group. Doppler sonography of the interlobar arteries and veins of both kidneys then was performed, with the sonographer unaware of which kidney had an obstruction. Peak venous flow measurements and arterial resistive and venous impedance indexes were obtained. The impedance indexes of the obstructed and unobstructed kidney were compared for each patient. The mean arterial resistive indexes of the obstructed kidneys were larger than those of the unobstructed kidneys, 0.67 +/- 0.08 and 0.62 +/- 0.05, respectively (p = 0.05). The venous impedance indexes comparing obstructed and unobstructed sides were 0.38 +/- 0.25 and 0.80 +/- 0.25, respectively, a statistically significant result (p = 0.0002). On average, the peak venous flow signal in the obstructed kidney was 69% higher than that of the unobstructed kidney (p = 0.04) and 86% higher than that of the peak venous flow signal in the control group (p = 0.005). Renal obstruction alters the venous flow to a greater extent than the arterial flow, and a comparison between the venous flow in the obstructed and unobstructed kidneys may improve diagnostic accuracy.
Publisher: Research Square Platform LLC
Date: 13-04-2022
DOI: 10.21203/RS.3.RS-1543872/V1
Abstract: The cross-sectional area of the superior sagittal sinus (SSS) is larger in multiple sclerosis than normal and correlates with disease severity and progression. The sinus could be enlarged due to a decrease in the pressure difference between the lumen and the subarachnoid space, an increase in wall thickness or increased wall stiffness. The cross-sectional area of the SSS and straight sinus (ST) were measured in 103 patients with multiple sclerosis and compared to 50 controls. The cross-sectional area of the SSS and ST were increased by 20% and 13% compared to the controls (p = 0.005 and 0.02 respectively). The deflection of the wall of the sinus was estimated. The change in pressure gradient, wall thickness or elastic modulus between groups was calculated by modelling the walls as simply supported beams. To account for these findings, the modelling suggests either a 70% reduction in transmural venous pressure or a 3 fold increase in SSS wall stiffness plus an 11% increase in wall thickness. An increase in sinus pressure, although the most straight forward possibility to account for the change in sinus size, may be the least feasible. An increase in sinus wall stiffness and thickness may need further investigation.
Publisher: Springer Science and Business Media LLC
Date: 29-07-2022
DOI: 10.1038/S41598-022-17465-9
Abstract: Dogs with a naturally occurring form of hydrocephalus have an elevated transmural venous pressure leading to cortical vein dilatation. The purpose of this study is to discover if there is vein dilatation in childhood hydrocephalus and to estimate the pressure required to maintain any enlargement found. Children with hydrocephalus between the ages of 4 and 15 years were compared with a control group. Magnetic resonance venography (MRV) and flow quantification were performed. The arterial inflow, sagittal sinus and straight sinus venous outflow were measured and the outflow percentages compared to the inflow were calculated. The cross-sectional area of the veins were measured. There were a total of 18 children with hydrocephalus, compared to 72 age and sex matched control MRV’s and 22 control flow quantification studies. In hydrocephalus, the sagittal sinus venous return was reduced by 12.9%, but the straight sinus flow was not significantly different. The superficial territory veins were 22% larger than the controls but the vein of Galen was unchanged. There is evidence of a significant increase in the superficial vein transmural pressure in childhood hydrocephalus estimated to be approximately 4 mmHg. An impedance pump model is suggested to explain these findings.
Publisher: Elsevier BV
Date: 04-2008
DOI: 10.1016/J.JOCN.2007.03.018
Abstract: A reduction in the proportion of the arterial inflow drained by the superior sagittal sinus in idiopathic intracranial hypertension (IIH) patients without stenoses has been noted and this has suggested elevated collateral flow. This study defines the interaction between arterial inflow and venous outflow in patients with outflow stenoses and IIH. Forty patients with clinical IIH underwent standard MRI, MR venography and MR flow quantification studies of the cerebral arteries and veins. There were 21/40 patients with venous stenoses. The arterial inflow was 21% higher than normal (p=0.01) however, the superior sagittal sinus outflow was normal, giving a reduced percentage of venous outflow compared to inflow. Seven patients were followed up after remission of their symptoms and the arterial inflows and percentage outflow returned to normal. There is a spectrum of findings in IIH patients with stenoses have lower inflows than those with patent sinuses but still have evidence of collateral flow.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2012
Publisher: SAGE Publications
Date: 19-12-2014
Abstract: Background. Upper-limb (UL) dysfunction is experienced by up to 75% of patients poststroke. The greatest potential for functional improvement is in the first month. Following reperfusion, evidence indicates that neuroplasticity is the mechanism that supports this recovery. Objective. This preliminary study hypothesized increased activation of putative motor areas in those receiving intensive, task-specific UL training in the first month poststroke compared with those receiving standard care. Methods. This was a single-blinded, longitudinal, randomized controlled trial in adult patients with an acute, first-ever ischemic stroke 23 participants were randomized to standard care (n = 12) or an additional 30 hours of task-specific UL training in the first month poststroke beginning week 1. Patients were assessed at 1 week, 1 month, and 3 months poststroke. The primary outcome was change in brain activation as measured by functional magnetic resonance imaging. Results. When compared with the standard-care group, the intensive-training group had increased brain activation in the anterior cingulate and ipsilesional supplementary motor areas and a greater reduction in the extent of activation ( P = .02) in the contralesional cerebellum. Intensive training was associated with a smaller deviation from mean recovery at 1 month (Pr F0 = 0.017) and 3 months (Pr F = 0.006), indicating more consistent and predictable improvement in motor outcomes. Conclusion. Early, more-intensive, UL training was associated with greater changes in activation in putative motor (supplementary motor area and cerebellum) and attention (anterior cingulate) regions, providing support for the role of these regions and functions in early recovery poststroke.
Publisher: Springer Science and Business Media LLC
Date: 16-01-2003
DOI: 10.1007/S00234-002-0901-0
Abstract: Superficial cortical venous compression secondary to alterations in craniospinal compliance is implicated in the pathogenesis of normal pressure hydrocephalus (NPH). A reduction in the pulsation in the outflow of the cortical veins would be expected to occur following compression of these veins and this has been shown in NPH. If cortical vein compression is a causative factor in NPH, it would be expected that cortical vein compliance as measured by pulsatility would be significantly altered by a curative procedure i.e. shunt tube insertion. My purpose is to compare the blood flow pulsatility characteristics in a group of patients with NPH before and after shunt tube insertion. I initially studied 18 subjects without pathology with MRI flow quantification studies of the cerebral arteries and veins to define the range of normality. The main study involved 18 patients with idiopathic dementia and mild leukoaraiosis who served as controls and seven patients with NPH studied before and after shunt insertion. Arterial, superior sagittal and straight sinus pulsatility was not significantly different between the patients with idiopathic dementia and those NPH patients before or after shunting. Cortical vein pulsatility before shunting in the patients with NPH was 43% lower than in those with idiopathic dementia ( P=0.006). Following shunting, cortical vein pulsatility increased by 186% ( P=0.007). There is thus reduced compliance in cortical veins in NPH which is significantly increased in patients who respond to insertion of a shunt tube. These findings suggest that reversible elevation in cortical vein pressure and reversal of the normal absorption pathway for cerebrospinal fluid may be behind the pathophysiology of NPH.
Publisher: MDPI AG
Date: 06-11-2015
Publisher: Frontiers Media SA
Date: 2013
Publisher: Springer Science and Business Media LLC
Date: 20-10-2022
DOI: 10.1038/S41598-022-21810-3
Abstract: The cross-sectional area of the superior sagittal sinus (SSS) is larger in multiple sclerosis than normal and correlates with disease severity and progression. The sinus could be enlarged due to a decrease in the pressure difference between the lumen and the subarachnoid space, an increase in wall thickness or increased wall stiffness. The cross-sectional area of the SSS and straight sinus (ST) were measured in 103 patients with multiple sclerosis and compared to 50 controls. The cross-sectional area of the SSS and ST were increased by 20% and 13% compared to the controls ( p = 0.005 and 0.02 respectively). The deflection of the wall of the sinus was estimated. The change in pressure gradient, wall thickness or elastic modulus between groups was calculated by modelling the walls as simply supported beams. To account for these findings, the modelling suggests either a 70% reduction in transmural venous pressure or a 2.4 fold increase in SSS wall stiffness plus an 11% increase in wall thickness or a combination of changes. An increase in sinus pressure, although the most straight forward possibility to account for the change in sinus size may exist in only a minority of patients. An increase in sinus wall stiffness and thickness may need further investigation.
Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
Date: 10-2013
Publisher: Springer Science and Business Media LLC
Date: 27-10-2012
DOI: 10.1007/S00381-011-1617-4
Abstract: Despite 100 years of study, the theories of cerebrospinal fluid (CSF) formation and absorption remain controversial. Measuring CSF flow through the aqueduct using magnetic resonance imaging (MRI) provides a unique insight into the physiology of CSF hydrodynamics. The published data in adults tend to refute rather than support the prevailing theories of CSF flow. There are limited data regarding this metric in children. This paper seeks to measure the aqueduct flow in normal and hydrocephalic children to help formulate a more complete theory of CSF flow. Twenty-four children with communicating hydrocephalus aged from 4 months to 16 years underwent MRI flow quantification of the aqueduct measuring the net flow. The patients were compared to 19 controls. The controls revealed two different flow patterns: (1) an infantile pattern characterized by flow directed into the ventricular system and (2) a mature pattern with flow directed out of the ventricles, similar to the published findings in adults. In infants with communicating hydrocephalus, the aqueduct flow changed direction but was of similar magnitude compared with the controls (p = 0.001). In the older hydrocephalic children, the flow was elevated 7-fold, but the direction was unchanged compared to the controls (p = 0.002). There is an abrupt change in the aqueduct CSF flow pattern at the age of 2 years from an infantile pattern to a mature pattern. These findings together with the findings in hydrocephalic children do not support the current theories of CSF hydrodynamics. A new theory of CSF circulation based on capillary absorption is presented.
Publisher: Elsevier BV
Date: 11-2020
Publisher: Oxford University Press (OUP)
Date: 09-06-2009
DOI: 10.1093/BRAIN/AWP155
Abstract: It is unknown whether collateral vessel status, as seen on computed tomography angiography, can predict the fate of penumbral tissue identified on perfusion computed tomography and thereby influence clinical outcome. We tested this hypothesis in consecutive patients who underwent perfusion computed tomography/computed tomography angiography within 6 h of anterior circulation stroke, who also had repeat perfusion/infarct volume imaging at 24 h, and modified Rankin Scale at 3 months. Collateral status was graded as good or reduced depending on the extent of contrast visualized distal to the occlusion on computed tomography angiography. 'Perfusion computed tomography mismatch' ratio was calculated from the ratio of the mean transit time lesion/cerebral blood volume lesion. Of 92 patients with proximal intracranial vessel occlusion, good collateral status (51/92) was significantly associated with reduced infarct expansion and more favourable functional outcomes (modified Rankin Scale 0-2). Significant univariate predictors of favourable outcome were good collateral status, major reperfusion at 24 h, presence of perfusion computed tomography mismatch (for a range of ratios: > or = 1.2, > or = 2, > or = 3, > or = 3.5) and baseline National Institutes of Health Stroke Scale score. Notably, none of the 37 patients with a perfusion computed tomography mismatch ratio < 3.0 had a favourable outcome. In patients with perfusion computed tomography mismatch, significant independent predictors of favourable outcome were good collateral status, major reperfusion and baseline National Institutes of Health Stroke Scale score. There was also a strong interaction between major reperfusion and good collateral status in the regression models. In patients with proximal vessel occlusion, perfusion computed tomography mismatch is a prerequisite for a favourable clinical response, but good collateral status appears a critical determinant of ultimate outcome, particularly if major reperfusion occurs.
Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
Date: 07-2016
Abstract: Ventricular dilation secondary to tumor obstruction of the posterior fossa CSF outflow in childhood is an intraaxial process. However, third ventriculostomy or complete tumor removal often fails to reduce the pressure in some children, and in others there is a delayed reduction in intracranial pressure this is termed the adaptation period. The cause of this adaptation period has not been studied. Venous sinus compression is highly correlated with other forms of childhood hydrocephalus, and this study seeks to follow the changes that occur in sinus cross-sectional area after surgery. Twelve children with posterior fossa tumors underwent MRI examination that included standard T2-weighted and 3D contrast-enhanced images obtained preoperatively, in the immediate postoperative period, and after several months. The volumes of the lateral and third ventricles and the minimum cross-sectional area of the transverse and sigmoid sinuses were measured. Patients were categorized by 1) shunt status (those who required a shunt vs those who did not) and 2) by age (those younger than 3 years vs those older than 3 years at diagnosis). There was a significant reduction in ventricular volume in both the immediate and secondary follow-up periods for all patients. There was preoperative venous sinus compression in all groups, which did not change significantly in the immediate postoperative period but did improve in the secondary follow-up period. The younger children had larger ventricles and smaller sinuses before surgery compared with the older children. In children with obstructed hydrocephalus caused by tumor, there is secondary compression of venous outflow, indicating both an intra- and extraaxial process. The expansion of the sinuses following decompression of the posterior fossa is delayed and may correlate with the adaptation period. Younger children have greater sinus compression than older ones.
Publisher: Georg Thieme Verlag KG
Date: 11-01-2023
DOI: 10.1055/A-1994-9759
Publisher: American Society of Neuroradiology (ASNR)
Date: 09-10-2008
DOI: 10.3174/AJNR.A0739
Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
Date: 12-2007
Publisher: Springer Science and Business Media LLC
Date: 15-07-2005
DOI: 10.1007/S00234-005-1418-0
Abstract: Variable results are obtained from the treatment of normal pressure hydrocephalus (NPH) by shunt insertion. There is a high correlation between NPH and the pathology of Alzheimer's disease (AD) on brain biopsy. There is an overlap between AD and vascular dementia (VaD), suggesting that a correlation exists between NPH and other forms of dementia. This study seeks to (1) understand the physiological factors behind, and (2) define the ability of, the aqueduct stroke volume to exclude dementia co-morbidity. Twenty-four patients from a dementia clinic were classified as having either early AD or VaD on the basis of clinical features, Hachinski score and neuropsychological testing. They were compared with 16 subjects with classical clinical findings of NPH and 12 aged-matched non-cognitively impaired subjects. MRI flow quantification was used to measure aqueduct stroke volume and arterial pulse volume. An arterio-cerebral compliance ratio was calculated from the two volumes in each patient. The aqueduct stroke volume was elevated in all three forms of dementia, with no significant difference noted between the groups. The arterial pulse volume was elevated by 24% in VaD and reduced by 35% in NPH, compared to normal (P = 0.05 and P = 0.002, respectively), and was normal in AD. There was a spectrum of relative compliance with normal compliance in VaD and reduced compliance in AD and NPH. The aqueduct stroke volume depends on the arterial pulse volume and the relative compliance between the arterial tree and brain. The aqueduct stroke volume cannot exclude significant co-morbidity in NPH.
Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
Date: 2010
Abstract: In the majority of adults with idiopathic intracranial hypertension (IIH), there is an elevation in venous pressure associated with a venous outflow stenosis. In about 15% of IIH patients the elevated venous pressure is associated with an elevation in blood flow but little or no evidence of a stenosis. Venostenotic IIH and idiopathic hydrocephalus in children with a normal blood inflow have been shown to be equivalent. The aim of this study was to test whether children with hydrocephalus and an elevated arterial inflow have a vascular pathophysiology that is analogous to the hyperemic form of IIH in adults. Nine children with idiopathic hydrocephalus underwent MR imaging with flow quantification and were found to have arterial inflows 2 SDs above the mean for normal controls. Measurements of the head circumference, ventricular enlargement, total blood inflow, superior sagittal sinus (SSS)/straight sinus (SS) outflow, and the degree of collateral venous flow were performed. The results were compared with findings in 14 age-matched controls. In hyperemic hydrocephalus the cerebral blood inflow was elevated but the SSS and SS outflows were in the normal range. The sinus outflow as a percentage of the inflow was reduced by 8 percentage points in the SSS territory and 5 percentage points in the SS territory compared with findings in the controls (p = 0.04, p = 0.003, respectively), suggesting blood was returning via collateral channels. Similar to patients with hyperemic IIH, children with hyperemic hydrocephalus show a significant elevation in collateral venous flow, indicating that the same venous pathophysiology may be operating in both conditions.
Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
Date: 12-2007
Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
Date: 02-2014
DOI: 10.3171/2013.10.PEDS13343
Abstract: It is known that CSF ersion in neonatal hydrocephalus can significantly increase cerebral blood flow, suggesting that a rapidly reversible elevation in vascular resistance underlies this disorder. Various sites of vascular compression have been described in the literature, from the arterioles to the capillary bed to the venules and sinuses. The purpose of this study was to define the site of the hemodynamically significant vascular compression seen in neonatal hydrocephalus. The author performed a retrospective review of all patients who, in the first 28 days of life, had undergone 3-T MRI examination, including MR venography and susceptibility weighted scanning, at a tertiary care referral hospital in the period from April 2010 to April 2013. The maximum size of the subependymal veins over the thalamus and transverse sinuses was measured. Three children with hydrocephalus were identified, and 10 children with a normal ventricular size served as controls. The subependymal veins were twice as prominent and the transverse sinuses were half as large in the patients with hydrocephalus compared with those in controls. The hemodynamically significant elevation in vascular resistance, which occurs in neonatal hydrocephalus, appears to be located in the venous sinuses.
Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
Date: 10-2013
Publisher: Massachusetts Medical Society
Date: 22-03-2012
Publisher: Springer Science and Business Media LLC
Date: 29-09-2020
DOI: 10.1186/S12987-020-00221-4
Abstract: Children referred to a tertiary hospital for the indication, “rule out idiopathic intracranial hypertension (IIH)” may have an increased risk of raised venous sinus pressure. An increase in sinus pressure could be due to obesity, venous outflow stenosis or cerebral hyperemia. The purpose of this paper is to define the incidence of each of these variables in these children. Following a data base review, 42 children between the ages of 3 and 15 years were found to have been referred over a 10 year period. The body mass index was assessed. The cross sectional areas and circumferences of the venous sinuses were measured at 4 levels to calculate the hydraulic and effective diameters. The arterial inflow, sagittal and straight sinus outflows were measured. Automatic cerebral volumetry allowed the brain volume and cerebral blood flow (CBF) to be calculated. The optic nerve sheath diameter was used as a surrogate marker of raised intracranial pressure (ICP). The sagittal sinus percentage venous return was used as a surrogate marker of elevated venous pressure. Age and sex matched control groups were used for comparison. Compared to controls, the obesity rates were not significantly different in this cohort. Compared to controls, those at risk for IIH had a 17% reduction in transverse sinus and 14% reduction in sigmoid sinus effective cross sectional area (p = 0.005 and 0.0009). Compared to controls, the patients at risk for IIH had an arterial inflow increased by 34% (p 0.0001) with a 9% larger brain volume (p = 0.02) giving an increase in CBF of 22% (p = 0.005). The sagittal and straight sinus venous return were reduced by 11% and 4% respectively (p 0.0001 and 0.0009) suggesting raised venous sinus pressure. Forty five percent of the patients were classified as hyperemic and these had optic nerve sheath diameters 17% larger than controls (p 0.0002) suggesting raised ICP. In children with the chronic headache/ IIH spectrum, the highest associations were with cerebral hyperemia and mild venous sinus stenosis. Obesity was not significantly different in this cohort. There is evidence to suggest hyperemia increases the venous sinus pressure and ICP.
Publisher: Springer Science and Business Media LLC
Date: 22-09-2016
Publisher: MDPI AG
Date: 20-10-2023
DOI: 10.3390/JCM12206646
Publisher: Oxford University Press (OUP)
Date: 09-2020
Publisher: SAGE Publications
Date: 12-04-2017
Abstract: The connection between ownership structure and firm performance has attracted significant attention especially in emerging markets, yet empirical evidence remains inconsistent. This article presents an analysis of the association among eight categories of ownership, Hirschman–Herfindahl index (HHI) index, Gini index, and firm performance in the emerging market of Pakistan. Some researchers argue that ownership concentration can improve firm performance by making the owners more willing or able to monitor agents. In contrast, others argue that in the presence of efficient markets, market monitoring will discipline the managers. Our results show that there is a significant positive association between ownership structure and both market-based performance measures and also economic profit. The ownership proportion of the institutional shareholding and foreign shareholding is also positively associated with firm performance.
Publisher: Springer Science and Business Media LLC
Date: 12-07-2005
Publisher: Springer Science and Business Media LLC
Date: 18-10-2011
Publisher: Wiley
Date: 06-03-2020
DOI: 10.1111/ANS.15024
Publisher: Elsevier BV
Date: 11-2021
DOI: 10.1016/J.MSARD.2021.103262
Abstract: The theory that multiple sclerosis is related to venous pressure has been discredited due to previous operator dependent diagnostic criteria and premature attempts at treatment. (1) An elevation in venous pressure may only be a component of the compliance changes found in MS. (2) The neck veins may only supply a component of the venous pressure elevation found intracranially. Although a more targeted approach towards neck angioplasty (both towards disease subtype and those with more favorable stenoses) may be beneficial, we would advocate caution. We encourage others to give the venous pressure theory a second chance and to replicate our work.
Publisher: Springer Science and Business Media LLC
Date: 15-02-2022
DOI: 10.1038/S41526-022-00188-6
Abstract: Spaceflight associated neuro-ocular syndrome (SANS) alters the vision of astronauts during long-duration spaceflights. There is controversy regarding SANS being similar to patients with idiopathic intracranial hypertension (IIH). IIH has been shown to be due to an elevation in venous sinus pressure. The literature suggests an increase in jugular vein pressure secondary to a headward shift of fluid occurs in SANS but this may not be enough to significantly alter the intracranial pressure (ICP). The literature regarding cardiac output and cerebral blood flow (CBF) in long-duration spaceflight is contradictory, however, more recent data suggests increased flow. Recent modelling has shown that an increase in CBF can significantly increase sinus pressure. The purpose of the present paper is to review the SANS vascular dynamics literature and through mathematical modelling suggest the possible underlying cause of SANS as an elevation in venous sinus pressure, secondary to the redistribution of fluids towards the head, together with a significant increase in pressure drop across the venous system related to the CBF.
Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
Date: 11-2007
Abstract: Findings in animal models of noncommunicating hydrocephalus have suggested that a reduction in compliance of the superior sagittal sinus, an elevation in venous outflow pressure, and the development of venous collateral flow may be associated with this condition. Although elevated venous pressure is known to cause hydrocephalus in children, this mechanism has fallen out of favor as a theory in adults. Twenty-one patients with late-onset idiopathic aqueductal stenosis (LIAS) underwent magnetic resonance imaging with flow quantification measuring the degree of ventricular enlargement, sulcal compression, total blood inflow, superior sagittal/straight sinus outflow, aqueduct flow, arteriovenous delay (AVD), and the extent of collateral venous flow. Data obtained in these patients were compared with those obtained in 21 age-matched control in iduals. There was a reduction in compliance in the patients with LIAS in whom the AVD decreased by 50% (p = 0.01). The arterial inflow and the straight sinus outflow were normal, but the sagittal sinus outflow was reduced by 23% (p = 0.001). This indicated that significant collateral venous outflow pathways were draining blood away from the superficial but not the deep drainage system. Similar to the animal models, patients with LIAS exhibit a reduced venous compliance and an elevation in venous collateral flow. Together, these findings suggest that an elevation in venous pressure may be associated with this disease process. A review of the literature has indicated that only subtle differences may exist in the pathophysiology among patients with LIAS, normal-pressure hydrocephalus, and idiopathic intracranial hypertension.
Publisher: Elsevier BV
Date: 2022
DOI: 10.1016/J.MSARD.2021.103477
Abstract: Multiple Sclerosis (MS) is a complex neurodegenerative condition that is influenced by a combination of genetic and environmental factors. Included in these factors is the venous system, however, the extent to which it influences the etiology of MS has yet to be fully characterised. The aim of this review is to critically summarize the literature available concerning the venous system in MS, primarily concerning specific data on the venous pressure and blood flow in this system. A systematic review was conducted with the application of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. The advanced search functions of both the Scopus and PubMed databases were used to conduct the literature search, resulting in 136 unique articles initially identified. Applying relevant exclusion criteria, 22 of the studies were chosen for this review. The selected studies were analysed for venous pressure and blood flow related findings, with 14 studies contributing data on the internal jugular vein (IJV) flow rate, 5 on blood flows of the intracranial venous sinuses, 2 on blood flow pulsatility and 6 supplying information relevant to the venous pressure (3 studies contributed to multiple areas). The general findings of the review included that the IJV flow was not significantly different between MS patients and controls, however, there were variances between stenotic (S) and non-stenotic (NS) MS patients. Due to the limited data in the other two areas defined in this review, further research is required to establish if any variances in MS are present. It remains unclear if there are significant differences in many flow variables between MS patients and controls considered in this review. It would be advantageous if future work in this area focused on understanding the hemodynamics of this system, primarily concerning how the flow rate, venous pressure and vascular resistance are related, and any impact that these factors have on the etiology of MS.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-03-2009
DOI: 10.1212/01.WNL.0000344168.05315.9D
Abstract: Tenecteplase is a modified tissue plasminogen activator with a longer half-life and higher fibrin specificity than alteplase. We conducted a prospective, nonrandomized, pilot study of 0.1 mg/kg IV tenecteplase given 3 to 6 hours after ischemic stroke onset. For a control group, we used patients contemporaneously treated with sub-3-hour 0.9 mg/kg IV alteplase following standard selection criteria. All patients underwent pretreatment and 24-hour perfusion/angiographic imaging with CT or MRI. Eligibility criteria for tenecteplase (but not alteplase) treatment included a perfusion lesion at least 20% greater than the infarct core, with an associated vessel occlusion. Primary outcomes, assessed blind to treatment group, were reperfusion (reduction in baseline-24-hour mean transit time lesion) and major vessel recanalization. Fifteen patients received tenecteplase, and 35 patients received alteplase. The tenecteplase group had greater reperfusion (mean 74% vs 44% in the alteplase group, p = 0.01) and major vessel recanalization (10/15 tenecteplase vs 7/29 alteplase, p = 0.01). Despite later time to treatment, more tenecteplase patients (10/15 vs 7/35 alteplase, p = 0.001) had major neurologic improvement at 24 hours (NIH Stroke Scale reduction > or = 8). Four of the alteplase patients and none of the tenecteplase patients had parenchymal hematoma at 24 hours. Tenecteplase 0.1 mg/kg, using advanced imaging guidance in an extended time window, may have significant biologic efficacy in acute ischemic stroke. The imaging selection differences between the tenecteplase and alteplase groups prevent a conclusive efficacy comparison. Nonetheless, these results lend support for randomized trials comparing tenecteplase with alteplase, preferably incorporating penumbral/angiographic imaging selection.
Publisher: Oxford University Press (OUP)
Date: 11-2013
DOI: 10.2522/PTJ.20120477
Abstract: Manual therapy of the cervical spine has occasionally been associated with serious adverse events involving compromise of the craniocervical arteries. Ultrasound studies have shown certain neck positions can alter craniocervical arterial blood flow velocities however, findings are conflicting. Knowledge about the effects of neck position on blood flow may assist clinicians in avoiding potentially hazardous practices. The purpose of this study was to examine the effects of selected manual therapeutic interventions on blood flow in the craniocervical arteries and blood supply to the brain using magnetic resonance angiography (MRA). This was an experimental, observational magnetic resonance imaging study. Twenty adult participants who were healthy and had a mean age of 33 years were imaged using MRA in the following neck positions: neutral, rotation, rotation/distraction (similar to a Cyriax manipulation), C1–C2 rotation (similar to a Maitland or osteopathic manipulation), and distraction. The participants were imaged using 3T MRA. All participants had normal vascular anatomy. Average inflow to the brain in neutral was 6.98 mL/s and was not significantly changed by any of the test positions. There was no significant difference in flow in any of the 4 arteries in any position from neutral, despite large in idual variations. Only in iduals who were asymptomatic were investigated, and a short section of the arteries only were imaged. Blood flow to the brain does not appear to be compromised by positions commonly used in manual therapy. Positions using end-range neck rotation and distraction do not appear to be more hazardous to cerebral circulation than more segmentally localized techniques.
Publisher: Oxford University Press (OUP)
Date: 25-03-2015
DOI: 10.1093/BRAIN/AWV071
Publisher: Springer Science and Business Media LLC
Date: 20-06-2002
DOI: 10.1007/S00234-002-0812-0
Abstract: There is a strong association between the occurrence of leukoaraiosis and normal-pressure hydrocephalus (NPH). Venous compression secondary to alterations in craniospinal compliance is implicated in the pathogenesis of NPH, and venous pathology has also been implicated in leukoaraiosis. The purpose of this paper is to compare and contrast the blood-flow and fluid-pulsatility characteristics of these conditions. I initially studied 18 subjects without pathology, with MRI flow-quantification studies of the cerebral arteries and veins, to define the range of normality. The main study involved 10 patients with idiopathic dementia but no leukoaraiosis who served as controls, 50 with idiopathic dementia with varying degrees of leukoaraiosis and 18 with NPH. I compared blood-flow volumes, vascular pulse-wave litudes and velocities. There was no significant difference in blood flow across the dementia patients. In patients with moderate leukoaraiosis, arterial pulsatility was 69%, cerebrospinal fluid (CSF) pulsation 104%, sagittal sinus pulsatility 48% and cortical vein pulsatility 34% higher than in demented patients without leukoaraiosis. Patients with NPH showed similar results with arterial pulsatility increased by 56% and sagittal sinus pulsatility by 70%. By contrast, the NPH patients' CSF pulse was 42% and the pulse wave delay at the sagittal sinus 50% less than in moderate leukoaraiosis. Thus, leukoaraiosis and NPH share increased arterial and sinus pulsatility. In leukoaraiosis cortical vein compliance is initially increased but in severe leukoaraiosis and NPH it is reduced.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-03-2007
DOI: 10.1212/01.WNL.0000256366.86353.FF
Abstract: To correlate the two types of early ischemic change on noncontrast CT (NCCT) (parenchymal hypoattenuation [PH] and isolated focal swelling [IFS]) with concurrent assessment of cerebral perfusion and to compare their rates of progression to infarction. We assessed cortical regions on NCCT for early ischemic change. Quantitative perfusion values were calculated for cortical regions from acute CT perfusion (CTP) maps of cerebral blood volume (CBV), blood flow (CBF), and mean transit time (MTT). Reperfusion and presence of infarction were determined from follow-up MRI. We studied 40 patients with sub-6 hour anterior circulation ischemic stroke 19 received IV recombinant tissue plasminogen activator. Of the 202 regions acutely hypoperfused on CTP, 123 were normal on NCCT, 58 had PH, and 21 had IFS. Acute CBV was low in PH regions, and elevated in IFS regions. Acute CBF was reduced in IFS regions, but more so in PH regions. Progression to infarction occurred in virtually all PH regions, but IFS regions had much lower rates of infarction with major reperfusion. Acute CBV in hypoperfused normal NCCT regions ranged from reduced to elevated, with substantially differing risk of infarction. Isolated focal swelling identifies penumbral tissue and parenchymal hypoattenuation identifies infarct core. Although this has prognostic implications when assessing patient suitability for thrombolytic therapy, the majority of acutely hypoperfused regions appear normal on noncontrast CT. Perfusion CT can stratify the level of risk of subsequent infarction for normal-appearing regions on noncontrast CT.
Publisher: Elsevier BV
Date: 12-2015
DOI: 10.1016/J.MEHY.2015.08.028
Abstract: Most hypotheses trying to explain the pathophysiology of idiopathic syringomyelia involve mechanisms whereby CSF is pumped against a pressure gradient, from the subarachnoid space into the cord parenchyma. On review, these theories have universally failed to explain the disease process. A few papers have suggested that the syrinx fluid may originate from the cord capillary bed itself. However, in these papers, the fluid is said to accumulate due to impaired fluid drainage out of the cord. Again, there is little evidence to substantiate this. This proffered hypothesis looks at the problem from the perspective that syringomyelia and normal pressure hydrocephalus are almost identical in their manifestations but only differ in their site of effect within the neuraxis. It is suggested that the primary trigger for syringomyelia is a reduction in the compliance of the veins draining the spinal cord. This reduces the efficiency of the pulse wave d ening, occurring within the cord parenchyma, increasing arteriolar and capillary pulse pressure. The increased capillary pulse pressure opens the blood-spinal cord barrier due to a direct effect upon the wall integrity and interstitial fluid accumulates due to an increased secretion rate. An increase in arteriolar pulse pressure increases the kinetic energy within the cord parenchyma and this disrupts the cytoarchitecture allowing the fluid to accumulate into small cystic regions in the cord. With time the cystic regions coalesce to form one large cavity which continues to increase in size due to the ongoing interstitial fluid secretion and the hyperdynamic cord vasculature.
Publisher: Springer Science and Business Media LLC
Date: 11-08-2011
DOI: 10.1007/S00381-011-1549-Z
Abstract: The cause of external hydrocephalus in infants is largely unknown. However, familial macrocephaly and delayed maturation of the arachnoid granulations are thought to play a part in the idiopathic cases. Secondary cases of external hydrocephalus are associated with hemorrhage, meningitis, and elevated venous pressure. Recently, elevated venous pressure has been shown to be a much more common cause of communicating hydrocephalus in children than previously thought. The purpose of this study is to investigate venous pressure as a cause of external hydrocephalus. Six children with external hydrocephalus underwent an MRI examination including MR venography and MR flow quantification techniques. A chart review was performed to correlate the clinical findings with the MR findings. Six children with normal head circumferences and growth profile served as controls. The net aqueduct flow in both normal and hydrocephalic children was into the ventricles. There was a spectrum of blood flow findings in the infants with hydrocephalus. (1) Those with normal arterial inflow showed venous outflow stenoses or anomalies. (2) Those with normal MR venograms tended to have elevated cerebral blood inflow. The absorption of CSF in infants is into the capillary bed of the deep white matter rather than the arachnoid granulations. Absorption into a capillary bed depends on hydrostatic pressure. Similar to older children with communicating hydrocephalus, the infants in this cohort with external hydrocephalus showed evidence of an elevation in venous pressure. Elevated venous pressure may be a much more common cause of external hydrocephalus than previously recognized.
Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
Date: 03-2009
DOI: 10.3171/2008.6.17609
Abstract: A collapsible segment in the venous outflow has been noted in many patients with idiopathic intracranial hypertension (IIH). Mathematical modeling has shown that these collapsible segments can account for the elevated cerebrospinal fluid (CSF) pressures associated with IIH. However, the model required an elevated outflow resistance of up to 10 times normal to predict the CSF pressures actually found clinically. Measurement of blood flow in patients with IIH has shown that inflow rates vary, with higher rates noted in patients with lesser outflow stenoses. The aim of this work was to extend a simple model of cerebral hydrodynamics to accommodate a collapsible sinus and elevations in cerebral blood flow in accordance with in vivo measurements. Forty patients with IIH underwent MR imaging in which the degree of stenosis on MR venography was compared with the total blood inflow by using MR flow quantification. The relative outflow resistance in IIH was estimated using the CSF opening pressure. The patients were compared with 14 age-matched control in iduals. Patients were ided into 3 groups based on MR venography appearances (minimal stenosis, stenosis of 40–70% and 70% stenosis). In vivo measurements suggested a relative resistance elevation of 2.5 times normal, 4.2 times normal, and 4.8 times normal in the 3 groups, respectively. There was an increased inflow of 1.56 times normal, 1.28 times normal, and 1.19 times normal in these groups. The model correctly predicted the CSF pressures noted in vivo, suggesting that high arterial inflow is required for patients with low-grade stenoses to be symptomatic.
Publisher: Springer Science and Business Media LLC
Date: 04-2008
DOI: 10.1007/S00234-008-0374-X
Abstract: Cerebral arterial, venous and cerebrospinal fluid (CSF) pulsations are closely coupled and this produces pulsation d ening or the windkessel effect. Normal pressure hydrocephalus is a manifestation of the breakdown of this windkessel effect with altered CSF and venous pulsations being noted. The aim of this study was to show that dysfunction of the windkessel mechanism is also a component of normal aging and senile dementia. The study group comprised 24 patients classified as either early senile dementia of Alzheimer's type (SDAT) or vascular dementia (VaD). The patients with dementia were compared with 12 age-matched non-cognitively impaired subjects, and 12 normal young in iduals were compared with the normal aging group. MRI flow quantification was used to measure the nonpulsatile and pulsatile components of blood flow as well as the pulsation at the tentorial incisura. With normal aging blood flow decreased but arterial pulsations increased in volume by 49% (P=0.003). The CSF vented via the tentorial incisura does not change significantly with age and therefore increased venous pulsation is necessary. In patients with VaD the arterial pulse volume was higher by 24% and the straight sinus pulsation was higher by 57% than in normal aging subjects (P=0.05 and P=0.03, respectively). In patients with SDAT the total venous pulsation volumes were similar to those in normal aging subjects but there was less basal sinus pulsation. Normal aging, SDAT and VaD are associated with alterations in venous pulsation due to a breakdown of the windkessel effect.
Publisher: Elsevier BV
Date: 02-2006
DOI: 10.1016/J.JOCN.2005.03.030
Abstract: CT perfusion scanning produces dynamic contrast-enhanced brain images, but to generate and interpret the colour maps of cerebral perfusion from these source images requires specialist neuroimaging knowledge. We hypothesized that physicians without such training might still utilise the CT perfusion source images (CTPSI) to diagnose early ischaemic change. Fifteen patients had cerebral non-contrast CT (NCCT) and perfusion CT within 6 hours of hemispheric stroke onset. We tested 15 non-stroke clinicians and radiology trainees, plus three experts, in assessing the presence and extent of early ischaemic change on NCCT versus CTPSI. Day 5-7 CT or MRI was used as the gold standard. Agreement with follow-up imaging was poor for both detection, and extent of early ischaemic change on NCCT (kappa = 0.01-0.11). There was a marked improvement in agreement for both the presence and extent of early ischaemic change on CTPSI (kappa = 0.67-0.83). CTPSI were much more accurate than NCCT in identifying acute ischaemic change. 'Less expert' users accurately identified major early ischaemic change on acute CTPSI. These findings suggest that such physicians might utilise CTPSI to screen potential thrombolysis candidates.
Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
Date: 2010
Publisher: Springer Science and Business Media LLC
Date: 04-02-2013
DOI: 10.1186/S12987-021-00239-2
Abstract: It has been shown that idiopathic intracranial hypertension (IIH) in children is associated with cerebral hyperemia, which induces an increase in cerebral venous pressure. The current literature suggests venous pressure scales with blood flow in a linear fashion, however, a linear relationship would not raise the pressure high enough to induce IIH. There is, however, some evidence to suggest that this relationship could be quadratic in nature. The purpose of this paper is to characterize the relationship between cerebral blood flow and the pressure drop across the cerebral venous system. 10 CT venogram data sets were collected for this study, with 5 useable geometries created. Computational fluid dynamics (CFD) models were generated using these geometries, with 10 simulations conducted per patient. The flow rates tested ranged from 200 mL/min to 2000 mL/min. 3D pressure and velocity streamline distributions were created and analyzed for each CFD model, with pressure drops across the cerebral venous system determined. The effective and hydraulic diameters were determined at the superior sagittal sinus, transverse sinus and both proximal and distal sigmoid sinuses. A quadratic relationship between blood flow and sinus pressure was found, with correlations of 0.99 or above in all five patients. The presence of vortical blood flow was found to explain this trend, with fluid curl and pressure drop correlations being above 0.97. This suggests that the presence of high blood flow should be considered in the diagnostic workup of IIH. The cerebral venous sinus blood flow and pressure response relationship are quadratic in nature, with the major cause of this being the degree of rotation induced in the flow. The elevated blood flow found in children with IIH can explain the increased ICP that is found, secondary to the increase in venous pressure that develops.
Publisher: Elsevier BV
Date: 2004
Publisher: Elsevier BV
Date: 10-2021
Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
Date: 03-2009
Publisher: Springer Science and Business Media LLC
Date: 05-04-2007
DOI: 10.1007/S00701-007-1142-0
Abstract: Between 10 and 90% of patients with normal pressure hydrocephalus (NPH) treated with a shunt will improve but they risk significant morbidity/mortality from this procedure. NPH is treated hydrodynamically and it has been assumed that a hydrodynamic difference must exist to differentiate which patient will respond. The purpose of this study is to see whether MRI hydrodynamics can differentiate which patients will improve post shunting. Thirty-two patients with NPH underwent MRI with flow quantification measuring the degree of ventricular enlargement, sulcal compression, white matter disease, total blood inflow, sagittal sinus outflow, aqueduct stroke volume, relative compliance ratio and arteriovenous delay. Patients were followed up after shunt insertion to gauge the degree of improvement and were compared with 12 age-matched controls and 12 patients with Alzheimer's disease. 63% of patients improved with insertion. The responders were identical to the non-responders in all variables. The NPH patients were significantly different to the controls (e.g. Total blood inflow reduced 20%, sagittal sinus outflow reduced 35%, aqueduct stroke volume increased 210%, relative compliance ratio reduced 60% and arteriovenous delay reduced 57% with p = 0.007, 0.03, 0.04, 0.0002 and 0.0003 respectively. The patient's with Alzheimer's disease values were midway between the NPH and control patients. Significant hydrodynamic differences were noted between NPH and controls but these were unable to differentiate the responders from non-responders. The hydrodynamics of Alzheimer's disease makes exclusion of comorbidity from this disease difficult.
Publisher: Elsevier BV
Date: 2004
DOI: 10.1016/J.MEHY.2004.04.019
Abstract: Normal pressure hydrocephalus, Alzheimer's disease and syringomyelia appear to be completely unrelated diseases, however, they share a reduction in subarachnoid space compliance as part of their pathophysiology. This paper discusses the physiology of pulsatile fluid flow and its relationship to compliance/impedance. Unlike continuous or non-pulsatile flow where the vessel resistance and pressure gradient are the major determinants of the volume of fluid flowing, when the fluid flow in a vessel pulsates then the vessel compliance/impedance becomes important. A reduction in compliance in the craniospinal cavity in each of the three diseases discussed, leads to a limitation of the outflow vessel compliance. Therefore, there is an increase in outflow vessel impedance. The venous blood, CSF and interstitial brain/spinal cord fluid all have significantly pulsatile flow and an increase in the impedance of the fluid outflow in each disease would limit the volume of these fluids as they attempt to cross the subarachnoid space. It is hypothesised that a reduction in the efficiency of the outflow of venous blood, CSF and interstitial brain/spinal cord fluid would lead to the accumulation of CSF in NPH, cord fluid in syringomyelia and delay the excretion of beta amyloid via the interstitial drainage pathways in AD.
Publisher: Springer Science and Business Media LLC
Date: 2014
Publisher: Wiley
Date: 24-03-2006
DOI: 10.1002/ANA.20839
Publisher: Wiley
Date: 12-2004
DOI: 10.7863/JUM.2004.23.12.1607
Abstract: The elevation in blood pressure associated with preecl sia appears to be associated with a shift in the renal pressure natriuresis curve. Pressure natriuresis is modulated by renal medullary pressure. In obstructive uropathy, Doppler sonography has been used to indicate changes in renal venous impedance, possibly measuring alterations in medullary pressure and compliance in this condition. The hypothesis tested in this study was that an elevation in renal venous pulsation may occur in preecl sia compared with normal pregnancy. Seven patients with clinical evidence of preecl sia were referred for fetal well-being confirmation by sonography in the third trimester. Seven pregnant patients without renal disease or hypertension reviewed in the third trimester served as a control group. Doppler studies of the interlobar arteries and veins of both kidneys were performed, with a total of 14 kidneys imaged per group. Arterial and venous impedance indices were obtained. The impedance indices for the patients were compared by the Student t test. No significant difference was noted between the arterial resistive indices. The mean venous impedance index for the hypertensive patients was 0.50 +/- 0.12, and that for the control patients was 0.37 +/- 0.06 (P = .003). Preecl sia in the third trimester appears to be associated with altered medullary venous pulsation, possibly indicating reduced medullary pressure.
Publisher: Springer Science and Business Media LLC
Date: 26-03-2019
DOI: 10.1007/S00234-019-02192-2
Abstract: To identify if specific findings on magnetic resonance imaging (MRI) cerebrospinal fluid (CSF) flow studies can be utilised to identify which patients with idiopathic normal pressure hydrocephalus (iNPH) will have improved gait following a CSF tap test (TT). Prospective study of patients undergoing a CSF TT for iNPH. Functional gait was assessed using the timed up and go (TUG) test before and after the CSF TT. MRI CSF flow studies accompanied the CSF TT. The minimum clinically important difference for the TUG (3.63 s) was used as a cutoff value to categorise patients as responders to the CSF TT. Fifty-three patients underwent CSF TT and MRI CSF flow studies. Significant differences were identified between groups for (non-responder vs responder) superior sagittal sinus flow (47.10% vs 40.41%), sagittal sinus stroke volume (274 vs 176.5 μl), sagittal sinus to arterial stroke volume ratio (0.203 vs 0.164), sagittal sinus area (42.2 mm A link between gait improvement resulting from CSF drainage and sagittal sinus measurements indicates that the sagittal sinus may play a role in the manifestation of symptoms in iNPH. This may have implications for the diagnosis of iNPH and potentially inform clinical decision making regarding surgical intervention.
Publisher: Wiley
Date: 20-10-2005
DOI: 10.1002/ANA.20638
Abstract: The Alberta Stroke Program Early Computed Tomography Score (ASPECTS) has not been previously applied to perfusion CT (CTP). Five raters assigned ASPECTS to baseline noncontrast CT (NCCT), CT angiography source images (CTA-SI), CTP source images (CTP-SI), and CTP maps of cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) from 37 consecutive patients with less than 6-hour anterior circulation ischemic stroke. Major reperfusion was identified on follow-up imaging. Mean baseline ASPECTS was compared with follow-up imaging ASPECTS. Rates of favorable outcome were compared for dichotomized baseline ASPECTS. In patients with major reperfusion, mean CBV and CTP-SI ASPECTS closely predicted final infarct ASPECTS. In patients without major reperfusion, mean CBF and MTT ASPECTS best predicted final infarct ASPECTS. There were significant increases in rates of favorable outcome for CTP-SI and CBV ASPECTS of greater than 6, versus less than or equal to 6, but not for other baseline CT modalities. ASPECTS applied to CTP is more accurate at identifying the extent of reversible and irreversible ischemia and at predicting final clinical outcome than NCCTor CTA-SI.
Publisher: Research Square Platform LLC
Date: 23-08-2022
DOI: 10.21203/RS.3.RS-1976913/V1
Abstract: There is a physiological similarity between the hydrodynamics of hydrocephalus and multiple sclerosis (MS). Children with hydrocephalus have been found to have a significant enlargement of the cortical veins within the subarachnoid space, suggesting an increase in venous pressure. The purpose of this study is to discover if there is dilatation of the veins within the subarachnoid space in multiple sclerosis and to estimate the pressures required to maintain any enlargement found. 103 patients with MS were compared with a control group of 50 patients. Post contrast 3DT1 images were used. The cross-sectional area of the bridging cortical veins and the vein of Galen were measured. In MS, the superficial territory cortical veins were 29% larger and the veins of Galen were 25% larger than the controls. There is evidence of a significant increase in the bridging vein transmural pressure in MS, estimated to be approximately 6.5 mmHg in the superficial cortical veins. MS patients with significant fatigue have larger cortical veins than those who are not significantly fatigued.
Publisher: American Society of Neuroradiology (ASNR)
Date: 22-11-2019
DOI: 10.3174/AJNR.A5883
Publisher: Springer Science and Business Media LLC
Date: 06-07-2017
Publisher: Hindawi Limited
Date: 10-2007
Publisher: American Physiological Society
Date: 10-2021
Publisher: Therapeutic Guidelines Limited
Date: 02-2008
Publisher: Elsevier BV
Date: 06-2006
DOI: 10.1016/J.JOCN.2005.06.005
Abstract: Twenty-four patients with a clinical diagnosis of idiopathic intracranial hypertension underwent standard magnetic resonance (MR) imaging. On the basis of MR venography, two groups of patients could be identified: (i) one group with an intrinsic venous outflow obstruction (intrinsic) and (ii) a non-intrinsically obstructed (extrinsic) group. MRI flow quantification studies of the cerebral arteries and veins, measuring arterial blood inflow as well as superior sagittal sinus (SSS) and straight sinus (ST) outflow, were performed. The MR venography confirmed that there were 12 intrinsic patients and 12 extrinsic patients. In the intrinsic group, total arterial inflow was normal however, the SSS outflow was reduced by 35% (p=0.0001). Arterial inflow in extrinsic patients was 55% higher than normal (p=0.0001) however, the SSS flow was normal. In intrinsic venous outflow obstruction, total cerebral inflow is maintained despite a reduction in outflow. In the idiopathic cases, there was cerebral hyperaemia suggesting a derangement of autoregulation.
Publisher: Springer Science and Business Media LLC
Date: 29-04-2020
DOI: 10.1186/S12987-020-00194-4
Abstract: Symptomatic or active hydrocephalus in children is linked to an elevation in intracranial pressure (ICP), which is likely to be multifactorial in origin. The CSF outflow resistance, venous sinus resistance and total cerebral blood flow are likely factors in the ICP elevation. The purpose of this paper is to define the incidence, site and significance of venous sinus stenosis and/or cerebral hyperemia in a cohort of children diagnosed with hydrocephalus at a tertiary referral hospital. The imaging database was reviewed over a 10 year period and the index MRI of all children between the ages of 4 months and 15 years, who were diagnosed with treatment naive hydrocephalus of any type (excluding secondary to tumor) and had magnetic resonance venography (MRV) and flow quantification were selected. Patients were compared with children undergoing an MRI with MRV and flow quantification who were subsequently shown to have no abnormality. The cross-sectional area and circumference of the sinuses were measured at 4 levels. The hydraulic and effective diameters were calculated. An area stenosis of 65% or greater was deemed significant. A total cerebral blood flow greater than two standard deviations above the mean for controls was taken to be abnormal. There were a total of 55 children with hydrocephalus compared to 118 age matched control MRV’s and 35 control flow quantification studies. A high grade stenosis occurred in 56% of patients but in none of the controls (p 0.0001). The commonest site of narrowing was in the distal sigmoid sinus. Cerebral hyperemia occurred in 13% of patients but did not occur in the controls. The elevation in ICP in symptomatic hydrocephalus is multifactorial. Both high grade venous stenosis and cerebral hyperemia are common in childhood hydrocephalus. High grade stenosis was noted to be a risk factor for conservative management failure. Hyperemia was a good prognostic indicator.
Publisher: Elsevier BV
Date: 06-2006
DOI: 10.1016/J.JOCN.2005.04.017
Abstract: Alzheimer's disease (AD) and vascular dementia (VaD) both share significant vascular risk factors. The present study measures the haemodynamics of these diseases in absolute rather than relative terms. Twenty-four patients were classified as either early AD or VaD and were compared with 12 non-cognitively impaired subjects. Magnetic resonance imaging flow quantification was used to measure arterial inflow and arterial pulse volume. Mean vascular resistance and compliance were calculated. In AD, the arterial inflow was lower by 18%, resistance was higher by 23% and compliance of the arterial tree was lower by 20% compared with normal (p=0.01, 0.02 and 0.05, respectively). In VaD, the arterial pulse volume was higher by 24% and compliance was higher by 35% compared with normal (p=0.05 for both). Early VaD is characterized by normal blood flow, but increased pulsation. Reduced blood flow and an incompliant arterial tree characterize early AD.
Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
Date: 12-2013
Abstract: Symptomatic shunt malfunction without ventricular enlargement is known as slit ventricle syndrome (SVS). Patients presenting with this syndrome are not a homogeneous group. Of the 5 different types classified by Rekate, Type 1 is caused by CSF overdrainage and is associated with low pressures Types 2 and 3 are associated with shunt blockage and elevated CSF pressures Type 4 is cephalocranial disproportion that increases brain parenchymal pressure but not CSF pressure and Type 5 is headache unrelated to shunt function. The low and normal CSF pressure types are relatively well understood, but the high-pressure forms are more problematic. In the high-pressure forms of SVS it is said that the lack of ventricular dilation is related to a reduction in brain compliance analogous to idiopathic intracranial hypertension or pseudotumor cerebri. Despite this, there is little evidence in the literature to support this conjecture. With this in mind, 3 cases of SVS associated with elevated CSF pressure are presented. The MR venogram findings and hemodynamics of these 3 cases are shown to be identical to those of pseudotumor cerebri. A literature review indicates that an underlying venous impairment may be functioning in the patients who re-present with small ventricles following shunt malfunction.
Location: Australia
No related grants have been discovered for Grant Bateman.