1
|
Williams H. A unifying hypothesis for hydrocephalus and the Chiari malformations part two: The hydrocephalus filling mechanism. Med Hypotheses 2016; 94:30-9. [DOI: 10.1016/j.mehy.2016.06.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 06/04/2016] [Accepted: 06/09/2016] [Indexed: 10/21/2022]
|
2
|
Naz N, Jimenez AR, Sanjuan-Vilaplana A, Gurney M, Miyan J. Neonatal hydrocephalus is a result of a block in folate handling and metabolism involving 10-formyltetrahydrofolate dehydrogenase. J Neurochem 2016; 138:610-23. [DOI: 10.1111/jnc.13686] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 04/29/2016] [Accepted: 05/23/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Naila Naz
- Faculty of Life Sciences; The University of Manchester; Manchester UK
| | | | | | - Megan Gurney
- Faculty of Life Sciences; The University of Manchester; Manchester UK
| | - Jaleel Miyan
- Faculty of Life Sciences; The University of Manchester; Manchester UK
| |
Collapse
|
3
|
Mehrabian A, Abousleiman YN, Mapstone TB, El-Amm CA. Dual-porosity poroviscoelasticity and quantitative hydromechanical characterization of the brain tissue with experimental hydrocephalus data. J Theor Biol 2015; 384:19-32. [PMID: 26277735 DOI: 10.1016/j.jtbi.2015.08.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Revised: 07/31/2015] [Accepted: 08/03/2015] [Indexed: 12/30/2022]
Abstract
Hydromechanical brain models often involve constitutive relations which must account for soft tissue deformation and creep, together with the interstitial fluid movement and exchange through capillaries. The interaction of rather unknown mechanisms which produce, absorb, and circulate the cerebrospinal fluid within the central nervous system can further add to their complexity. Once proper models for these phenomena or processes are selected, estimation of the associated parameters could be even more challenging. This paper presents the results of a consistent, coupled poroviscoelastic modeling and characterization of the brain tissue as a dual-porosity system. The model draws from Biot's theory of poroviscoelasticity, and adopts the generalized Kelvin's rheological description of the viscoelastic tissue behavior. While the interstitial space serves as the primary porosity through which the bulk flow of the interstitial fluid occurs, a secondary porosity network comprising the capillaries and venous system allows for its partial absorption into the blood. The correspondence principle is used in deriving a time-dependent analytical solution to the proposed model. It allows for identical poroelastic formulation of the original poroviscoelastic problem in the Laplace transform space. Hydrocephalus generally refers to a class of medical conditions which share the ventricles enlargement as a common feature. A set of published data from induced hydrocephalus and follow-up perfusion of cats' brains is used for quantitative characterization of the proposed model. A selected portion of these data including the ventricular volume and rate of fluid absorption from the perfused brain, together with the forward model solution, is utilized via an inverse problem technique to find proper estimations of the model parameters. Results show significant improvement in model predictions of the experimental data. The convoluted and coupled solution results are presented through the time-dependent plots of the ventricular volume undergoing the perfusion experiment. The plots demonstrate the intricate interplay of viscous and poroelastic diffusive time scales, and their competition in reaching the steady state response of the system.
Collapse
Affiliation(s)
- Amin Mehrabian
- PoroMechanics Institute, Mewbourne School of Petroleum and Geological Engineering, University of Oklahoma, Norman, OK 73019
| | - Younane N Abousleiman
- Mewbourne School of Petroleum and Geological Engineering, School of Geology and Geophysics, School of Civil Engineering and Environmental Science, PoroMechanics Institute, University of Oklahoma, Norman, OK 73019.
| | - Timothy B Mapstone
- School of Medicine and Department of Neurosurgery, University of Oklahoma, Oklahoma City, OK 73104
| | - Christian A El-Amm
- Section of Plastic and Reconstructive Surgery, Department of Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
| |
Collapse
|
4
|
Changes in the cerebrospinal fluid circulatory system of the developing rat: quantitative volumetric analysis and effect on blood-CSF permeability interpretation. Fluids Barriers CNS 2015; 12:8. [PMID: 25793105 PMCID: PMC4365764 DOI: 10.1186/s12987-015-0001-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 01/30/2015] [Indexed: 12/27/2022] Open
Abstract
Background The 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. Methods Immunohistofluorescence 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. Results Claudin-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. Conclusion Reference 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 material The online version of this article (doi:10.1186/s12987-015-0001-2) contains supplementary material, which is available to authorized users.
Collapse
|
5
|
Paul L, Madan M, Rammling M, Chigurupati S, Chan SL, Pattisapu JV. Expression of aquaporin 1 and 4 in a congenital hydrocephalus rat model. Neurosurgery 2011; 68:462-73. [PMID: 21135737 DOI: 10.1227/neu.0b013e3182011860] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Hydrocephalus occurs because of an imbalance of bulk fluid flow in the brain, and aquaporins (AQPs) play pivotal roles in cerebral water movement as essential mediators during edema and fluid accumulation. AQP1 is a water channel found in the choroid plexus (CP), and AQP4 is expressed at the brain-CSF interfaces and astrocytic end feet; excessive fluid accumulation may involve expression of changes in these AQPs during various stages of hydrocephalus. OBJECTIVE To determine the alterations of CP AQP1 expression in congenital hydrocephalus; detect hydrocephalus-induced AQP1 expression in the cortical parenchyma, ependyma, and pia mater of hydrocephalic animals; and evaluate AQP4 expression in congenital hydrocephalus through progressive stages of the condition. METHODS We evaluated differential expression of AQPs 1 and 4 in the congenital hydrocephalus Texas rat at postnatal days 5, 10, and 26 in isolated CP and cortex by enzyme-linked immunosorbent assay, Western blot, quantitative reverse transcriptase polymerase chain reaction, and immunohistochemistry. RESULTS The CP exhibited a 34% decrease in AQP1 expression in young hydrocephalic pups (postnatal days 5 and 10), which became normal (postnatal day 26) just before death. With advancing hydrocephalus, expression of AQPs 1 and 4 increased at the brain-CSF interfaces; AQP1 was localized to the endothelium of cortical capillaries with increased AQP4 expression in surrounding astrocytes end feet. AQP1 expression level was increased in the pia mater, with prominent AQP4 expression in the subpial layers. Subependymal capillaries expressed AQP1 in the endothelium, with increasing AQP4 expression in surrounding astrocytes. Hydrocephalic animals (postnatal day 26) had significant nonendothelial (CD34) AQP1 expression in the septal nucleus of the basal forebrain, an area affected by increased intracranial pressure. CONCLUSION Biphasic AQP1 expression in the CP with increased AQPs 1 and 4 at the brain-fluid interfaces may indicate compensatory mechanisms to regulate choroidal cerebrospinal fluid secretion and increase parenchymal fluid absorption in the high-pressure hydrocephalic condition.
Collapse
Affiliation(s)
- Leena Paul
- Burnett School of Biomedical Science, College of Medicine, University of Central Florida Orlando, Florida, USA.
| | | | | | | | | | | |
Collapse
|
6
|
Del Bigio MR, Slobodian I, Schellenberg AE, Buist RJ, Kemp-Buors TL. Magnetic resonance imaging indicators of blood-brain barrier and brain water changes in young rats with kaolin-induced hydrocephalus. Fluids Barriers CNS 2011; 8:22. [PMID: 21834998 PMCID: PMC3162928 DOI: 10.1186/2045-8118-8-22] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 08/11/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Hydrocephalus is associated with enlargement of cerebral ventricles. We hypothesized that magnetic resonance (MR) imaging parameters known to be influenced by tissue water content would change in parallel with ventricle size in young rats and that changes in blood-brain barrier (BBB) permeability would be detected. METHODS Hydrocephalus was induced by injection of kaolin into the cisterna magna of 4-week-old rats, which were studied 1 or 3 weeks later. MR was used to measure longitudinal and transverse relaxation times (T1 and T2) and apparent diffusion coefficients in several regions. Brain tissue water content was measured by the wet-dry weight method, and tissue density was measured in Percoll gradient columns. BBB permeability was measured by quantitative imaging of changes on T1-weighted images following injection of gadolinium diethylenetriamine penta-acetate (Gd-DTPA) tracer and microscopically by detection of fluorescent dextran conjugates. RESULTS In nonhydrocephalic rats, water content decreased progressively from age 3 to 7 weeks. T1 and T2 and apparent diffusion coefficients did not exhibit parallel changes and there was no evidence of BBB permeability to tracers. The cerebral ventricles enlarged progressively in the weeks following kaolin injection. In hydrocephalic rats, the dorsal cortex was more dense and the white matter less so, indicating that the increased water content was largely confined to white matter. Hydrocephalus was associated with transient elevation of T1 in gray and white matter and persistent elevation of T2 in white matter. Changes in the apparent diffusion coefficients were significant only in white matter. Ventricle size correlated significantly with dorsal water content, T1, T2, and apparent diffusion coefficients. MR imaging showed evidence of Gd-DTPA leakage in periventricular tissue foci but not diffusely. These correlated with microscopic leak of larger dextran tracers. CONCLUSIONS MR characteristics cannot be used as direct surrogates for water content in the immature rat model of hydrocephalus, probably because they are also influenced by other changes in tissue composition that occur during brain maturation. There is no evidence for widespread persistent opening of BBB as a consequence of hydrocephalus in young rats. However, increase in focal BBB permeability suggests that periventricular blood vessels may be disrupted.
Collapse
Affiliation(s)
- Marc R Del Bigio
- Department of Pathology, University of Manitoba; 401 Brodie Centre, 727 McDermot Avenue, Winnipeg MB R3E 3P5 Canada.
| | | | | | | | | |
Collapse
|
7
|
Del Bigio MR, Enno TL. Effect of hydrocephalus on rat brain extracellular compartment. Cerebrospinal Fluid Res 2008; 5:12. [PMID: 18616813 PMCID: PMC2488327 DOI: 10.1186/1743-8454-5-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Accepted: 07/10/2008] [Indexed: 11/23/2022] Open
Abstract
Background The cerebral cortex may be compressed in hydrocephalus and some experiments suggest that movement of extracellular substances through the cortex is impaired. We hypothesized that the extracellular compartment is reduced in size and that the composition of the extracellular compartment changes in rat brains with kaolin-induced hydrocephalus. Methods We studied neonatal (newborn) onset hydrocephalus for 1 or 3 weeks, juvenile (3 weeks) onset hydrocephalus for 3–4 weeks or 9 months, and young adult (10 weeks) onset hydrocephalus for 2 weeks, after kaolin injection. Freeze substitution electron microscopy was used to measure the size of the extracellular compartment. Western blotting and immunohistochemistry with quantitative image densitometry was used to study the extracellular matrix constituents, phosphacan, neurocan, NG2, decorin, biglycan, and laminin. Results The extracellular space in cortical layer 1 was reduced significantly from 16.5 to 9.6% in adult rats with 2 weeks duration hydrocephalus. Western blot and immunohistochemistry showed that neurocan increased only in the periventricular white matter following neonatal induction and 3 weeks duration hydrocephalus. The same rats showed mild decorin increases in white matter and around cortical neurons. Juvenile and adult onset hydrocephalus was associated with no significant changes. Conclusion We conclude that compositional changes in the extracellular compartment are negligible in cerebral cortex of hydrocephalic rats at various ages. Therefore, the functional change related to extracellular fluid flow should be reversible.
Collapse
Affiliation(s)
- Marc R Del Bigio
- Department of Pathology, University of Manitoba, and Manitoba Institute of Child Health, Winnipeg MB, R3E 3P5, Canada.
| | | |
Collapse
|
8
|
Bashir Z, Miller J, Miyan JA, Thorniley MS. A near infrared spectroscopy study investigating oxygen utilisation in hydrocephalic rats. Exp Brain Res 2006; 175:127-38. [PMID: 16733697 DOI: 10.1007/s00221-006-0541-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Accepted: 04/26/2006] [Indexed: 11/26/2022]
Abstract
Determination of hydrocephalus and its severity is important for optimal management of the condition. We have used near infrared spectroscopy (NIRS) to assess changes in concentrations of oxygenated (O2Hb), deoxygenated (HHb), total haemoglobin (tHb) and cytochrome c oxidase (Caa3) in normal and hydrocephalic Texas (HTx) rats in response to a 5 min head down tilt and a sodium pentobarbitone (NaPB) challenge. The former was used to test vascular responses and the latter to test metabolic responses. The haemoglobin oxygenation index (HbD) was derived which provides information regarding oxygen utilisation ([HbD]=[O2Hb]-[HHb]). With the tilt challenge, a significant (P=0.001) difference was observed in [HbD] between normal (n=24) and hydrocephalic (n=14) rats (-3.50 (-6.00 to 0.00) microM cm(-1 )and 7.50 (0.75 to 14.25) microM cm(-1), respectively). In another experiment we tested the response of ten rats to NaPB administration and observed a significant difference (P=0.008) in [Caa3] between normal (n=5) and hydrocephalic (n=5) rats (-6.60 (-7.55 to -5.50) microM cm(-1 )and -2.20 (-5.60 to -1.05) microM cm(-1), respectively). Coronal sections of these ten rat brains were analysed and significant (P<0.05) relationships were found between some of the NIRS parameters and cortical thickness or lateral ventricle area measurements. Our studies demonstrate that a significant difference in cerebral oxygenation and haemodynamics can be observed between normal and hydrocephalic HTx rats using NIRS.
Collapse
Affiliation(s)
- Zareen Bashir
- School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, M60 1QD, UK.
| | | | | | | |
Collapse
|
9
|
Abstract
The literature concerning brain damage due to hydrocephalus, especially in children and animal models, is reviewed. The following conclusions are reached: 1. Hydrocephalus has a deleterious effect on brain that is dependent on magnitude and duration of ventriculomegaly and modified by the age of onset. 2. Animal models have many histopathological similarities to humans and can be used to understand the pathogenesis of brain damage. 3. Periventricular axons and myelin are the primary targets of injury. The pathogenesis has similarities to traumatic and ischemic white matter injury. Secondary changes in neurons reflect compensation to the stress or ultimately the disconnection. 4. Altered efflux of extracellular fluid could result in accumulation of waste products that might interfere with neuron function. Further research is needed in this as well as the blood-brain barrier in hydrocephalus. 5. Some, but not all, of the changes are preventable by shunting CSF. However, axon loss cannot be reversed, therefore shunting in a given case must be considered carefully. 6. Experimental work has so far failed to show any benefit in reducing CSF production. Pharmacologic protection of the brain, at least as a temporary measure, holds some promise but more pre-clinical research is required.
Collapse
Affiliation(s)
- Marc R Del Bigio
- Department of Pathology, University of Manitoba, and Manitoba Institute for Child Health, Winnipeg, Canada.
| |
Collapse
|
10
|
Gefen A, Gefen N, Zhu Q, Raghupathi R, Margulies SS. Age-Dependent Changes in Material Properties of the Brain and Braincase of the Rat. J Neurotrauma 2003; 20:1163-77. [PMID: 14651804 DOI: 10.1089/089771503770802853] [Citation(s) in RCA: 186] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Clinical and biomechanical evidence indicates that mechanisms and pathology of head injury in infants and young children may be different from those in adults. Biomechanical computer-based modeling, which can be used to provide insight into the thresholds for traumatic tissue injury, requires data on material properties of the brain, skull, and sutures that are specific for the pediatric population. In this study, brain material properties were determined for rats at postnatal days (PND) 13, 17, 43, and 90, and skull/suture composite (braincase) properties were determined at PND 13, 17, and 43. Controlled 1 mm indentation of a force probe into the brain was used to measure naive, non-preconditioned (NPC) and preconditioned (PC) instantaneous (G(i)) and long-term (G( infinity )) shear moduli of brain tissue both in situ and in vitro. Brains at 13 and 17 PND exhibited statistically indistinguishable shear moduli, as did brains at 43 and 90 PND. However, the immature (average of 13 and 17 PND) rat brain (G(i) = 3336 Pa NPC, 1754 Pa PC; G( infinity )= 786 Pa NPC, 626 Pa PC) was significantly stiffer (p < 0.05) than the mature (average of 43 and 90 PND) brains (G(i) = 1721 Pa NPC, 1232 Pa PC; G( infinity ) = 508 Pa NPC, 398 Pa PC). A "reverse engineering" finite element model approach, which simulated the indentation of the force probe into the intact braincase, was used to estimate the effective elastic moduli of the braincase. Although the skull of older rats was significantly thicker than that of the younger rats, there was no significant age-dependent change in the effective elastic modulus of the braincase (average value = 6.3 MPa). Thus, the increase in structural rigidity of the braincase with age (up to 43 PND) was due to an increase in skull thickness rather than stiffening of the tissue. These observations of a stiffer brain and more compliant braincase in the immature rat compared with the adult rat will aid in the development of age-specific experimental models and in computational head injury simulations. Specifically, these results will assist in the selection of forces to induce comparable mechanical stresses, strains and consequent injury profiles in brain tissues of immature and adult animals.
Collapse
Affiliation(s)
- Amit Gefen
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | | | | | | |
Collapse
|
11
|
Desai M, Ladella S, Ross MG. Reversal of pregnancy-mediated plasma hypotonicity in the near-term rat. J Matern Fetal Neonatal Med 2003; 13:197-202. [PMID: 12820842 DOI: 10.1080/jmf.13.3.197.202] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVE Maternal plasma hypotonicity occurs early in rat and human pregnancy with resetting of the plasma osmolality threshold for vasopressin secretion and thirst. In humans, amniotic fluid volume reaches maximum levels in the mid-third trimester and decreases thereafter. We hypothesized that a reversal of maternal plasma hypotonicity occurs near term, contributing to reduced fetal and amniotic fluid water content. METHODS Maternal plasma and amniotic fluid osmolality and sodium levels, including amniotic fluid volume, were measured at 16, 18 and 20 days of rat gestation. Additionally, maternal and fetal brains were analyzed for water and electrolyte content. Non-pregnant adult female rats represented controls. RESULTS Compared to non-pregnant adults, 16-day and 18-day pregnant rats had significantly lower plasma osmolality (301.0 +/- 2.3 vs. 295.4 +/- 2.8 and 289.7 +/- 3.3 mOsm/kg, respectively) and sodium levels (140.3 +/- 1.0 vs. 135.7 +/- 0.8 and 133.4 +/- 1.4 mEq/l, respectively). Conversely, 20-day pregnant rats showed no significant difference in plasma osmolality (298.4 +/- 3.1 mOsm/kg) or sodium levels (137.6 +/- 1.0 mEq/l) from non-pregnant adults. With advancing gestation, the amniotic fluid volume decreased whereas the osmolality and sodium levels increased significantly. Maternal brain water content was significantly higher in 16-day and 18-day pregnant rats compared to control rats (78.7 +/- 0.1 and 78.1 +/- 0.2 vs. 76.9 +/- 0.2% wet weight) and returned to non-pregnant values in the 20-day pregnant rats (76.6 +/- 0.2%). In association with the maternal changes, fetal brain water and electrolyte content significantly decreased from 16-day to 18-day to 20-day fetuses. CONCLUSION These findings indicate a reversal of maternal plasma hypotonicity and reduced maternal brain water content in the near-term pregnant rat. We speculate that relative maternal plasma hypertonicity near term may contribute to reduced amniotic fluid volume.
Collapse
Affiliation(s)
- M Desai
- Perinatal Research Laboratories, Department of Obstetrics and Gynecology, University of California Los Angeles School of Medicine, Harbor-University of California Los Angeles Medical Center, Torrance, California 90502, USA
| | | | | |
Collapse
|
12
|
|
13
|
Doyle JA, Davis DP, Hoyt DB. The use of hypertonic saline in the treatment of traumatic brain injury. THE JOURNAL OF TRAUMA 2001; 50:367-83. [PMID: 11242309 DOI: 10.1097/00005373-200102000-00030] [Citation(s) in RCA: 156] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- J A Doyle
- Department of Emergency Medicine, University of California at San Diego, 200 West Arbor Drive, San Diego, CA 92103-8676, USA
| | | | | |
Collapse
|
14
|
Massicotte EM, Buist R, Del Bigio MR. Altered diffusion and perfusion in hydrocephalic rat brain: a magnetic resonance imaging analysis. J Neurosurg 2000; 92:442-7. [PMID: 10701531 DOI: 10.3171/jns.2000.92.3.0442] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT It can be inferred from data published in the literature that brain compression occurs in the early stages of acute hydrocephalus and that drainage of extracellular waste products is impaired. The authors hypothesized that compression of the cortex would alter water distribution and retard the diffusion of fluid in the hydrocephalic brain. METHODS Proton diffusion, blood perfusion, and T1 and T2 relaxation times were determined in adult rat brain by using magnetic resonance imaging prior to, and 1 and 8 days after induction of hydrocephalus by kaolin injection. Five anatomical regions of interest were studied. The striatum, dorsal cortex, and lateral cortex exhibited decreased T2 and apparent diffusion coefficient (ADC) values but no change in perfusion. Examination of white matter revealed an initial decrease in ADC followed by a significant increase. The T2 relaxation times increased and perfusion decreased progressively between 1 and 8 days after induction of hydrocephalus. CONCLUSIONS Acute experimental hydrocephalus causes compression of gray matter, perhaps associated with reduction in total water, which impairs diffusion of water in the tissue. White matter compression and hypoperfusion precede the development of edema. These findings have importance for understanding the neurochemical changes that occur in hydrocephalic brains.
Collapse
Affiliation(s)
- E M Massicotte
- Department of Surgery, University of Manitoba and Health Sciences Centre, Winnipeg, Canada
| | | | | |
Collapse
|
15
|
Massicotte EM, Buist R, Del Bigio MR. Altered diffusion and perfusion in hydrocephalic rat brain: a magnetic resonance imaging analysis. Neurosurg Focus 1999. [DOI: 10.3171/foc.1999.7.4.14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
It can be inferred from data published in the literature that brain compression occurs in the early stages of acute hydrocephalus and that drainage of extracellular waste products is impaired. The authors hypothesized that compression of the cortical extracellular compartment will alter water distribution and retard the diffusion of fluid in the hydrocephalic brain.
Using magnetic resonance imaging proton diffusion, blood perfusion, and T1 and T2 relaxation times were determined in adult rat brain prior to, and 1 and 8 days following induction of hydrocephalus by using kaolin injection. Five anatomical regions of interest were studied. The striatum, dorsal cortex, and lateral cortex were shown to exhibit decreased T2 and apparent diffusion coefficient (ADC) values but no change in perfusion. Examination of white matter demonstrated an initial decrease in ADC followed by a significant increase. The T2 relaxation times increased and perfusion decreased progressively from 1 to 8 days.
Acute experimental hydrocephalus causes compression of gray matter, perhaps associated with reduction in total water, which impairs diffusion of protons in the tissue. White matter compression and hypoperfusion precede the development of edema. These findings have importance for understanding the neurochemical changes that occur in hydrocephalic brains.
Collapse
|
16
|
Socci DJ, Bjugstad KB, Jones HC, Pattisapu JV, Arendash GW. Evidence that oxidative stress is associated with the pathophysiology of inherited hydrocephalus in the H-Tx rat model. Exp Neurol 1999; 155:109-17. [PMID: 9918710 DOI: 10.1006/exnr.1998.6969] [Citation(s) in RCA: 210] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Oxidative stress can contribute to many neurological disease processes. Because many events known to involve oxidative stress (infection, hemorrhage, brain trauma) are accompanied by hydrocephalus, the present study sought to evaluate the relationship between oxidative stress and the progression of hydrocephalus. Assays for reactive oxygen species (ROS), using dichlorofluorescein (DCF) fluorescence, and lipid peroxidation, using malondialdehyde (MDA), were performed on brain tissue from the cerebral cortex, cerebellum, basal ganglia, and hippocampus of 4-, 10-, and 25-day-old normal and hydrocephalic H-Tx rats. These rats inherit hydrocephalus at a rate of 30-50% and represent a unique model for studying the progression of hydrocephalus. When hydrocephalic and normal H-Tx rats were compared, ROS levels were significantly higher in the cerebral cortex of 4-day-old and in the cerebellum and hippocampus of 4- and 10-day-old hydrocephalic rats. ROS levels also were significantly higher in the basal ganglia of 25-day-old hydrocephalic rats. MDA levels were significantly higher in the hippocampus and basal ganglia of 25-day-old hydrocephalic rats. There were no significant differences in MDA levels at younger ages. These results indicate that, in H-Tx rats, oxidative stress is associated with the progression and molecular pathophysiology of hydrocephalus. This association suggests that oxidative brain damage may represent an important factor resulting from or contributing to the pathogenesis of hydrocephalus.
Collapse
Affiliation(s)
- D J Socci
- Wade's Center for Hydrocephalus, Orlando Regional Healthcare System Health Research Institute, Orlando, Florida, 32806, USA
| | | | | | | | | |
Collapse
|