scholarly journals Modeling of Brain Shift Phenomenon for Different Craniotomies and Solid Models

2012 ◽  
Vol 2012 ◽  
pp. 1-20 ◽  
Author(s):  
Alvaro Valencia ◽  
Benjamin Blas ◽  
Jaime H. Ortega
Keyword(s):  
Elastic Solid ◽  
Brain Parenchyma ◽  
Solid Model ◽  
Elastic Model ◽  
Brain Shift ◽  
Healthy Human ◽  
Brain Surface ◽  
Solid Models ◽  
The Difference ◽  
The Brain

This study investigates the effects of different solid models on predictions of brain shift for three craniotomies. We created a generic 3D brain model based on healthy human brain and modeled the brain parenchyma as single continuum and constrained by a practically rigid skull. We have used elastic model, hyperelastic 1st, 2nd, and 3rd Ogden models, and hyperelastic Mooney-Rivlin with 2- and 5-parameter models. A pressure on the brain surface at craniotomy region was applied to load the model. The models were solved with the finite elements package ANSYS. The predictions on stress and displacements were compared for three different craniotomies. The difference between the predictions of elastic solid model and a hyperelastic Ogden solid model of maximum brain displacement and maximum effective stress is relevant.

scholarly journals Practical application of synthetic head models in real ballistic cases

2021 ◽  
Author(s):  
F. Riva ◽  
T. Fracasso ◽  
A. Guerra ◽  
P. Genet
Keyword(s):  
Soft Tissues ◽  
Spherical Model ◽  
Brain Parenchyma ◽  
Human Bone ◽  
Shape Model ◽  
The Difference ◽  
Open Shape ◽  
The Brain ◽  
Synthetic Models ◽  
Representative Material

AbstractIn shooting crimes, ballistics tests are often recommended in order to reproduce the wound characteristics of the involved persons. For this purpose, several “simulants” can be used. However, despite the efforts in the research of “surrogates” in the field of forensic ballistic, the development of synthetic models needs still to be improved through a validation process based on specific real caseworks. This study has been triggered by the findings observed during the autopsy performed on two victims killed in the same shooting incident, with similar wounding characteristics; namely two retained head shots with ricochet against the interior wall of the skull; both projectiles have been recovered during the autopsies after migration in the brain parenchyma. The thickness of the different tissues and structures along the bullets trajectories as well as the incident angles between the bullets paths and the skull walls have been measured and reproduced during the assemblage of the synthetic head models. Two different types of models (“open shape” and “spherical”) have been assembled using leather, polyurethane and gelatine to simulate respectively skin, bone and soft tissues. Six shots have been performed in total. The results of the models have been compared to the findings of post-mortem computed tomography (PMCT) and the autopsy findings.Out of the six shots, two perforated the models and four were retained. When the projectile was retained, the use of both models allowed reproducing the wounds characteristics observed on both victims in terms of penetration and ricochet behaviour. However, the projectiles recovered from the models showed less deformation than the bullets collected during the autopsies. The “open shape” model allowed a better controlling on the shooting parameters than the “spherical” model. Finally, the difference in bullet deformation could be caused by the choice of the bone simulant, which might under-represent either the strength or the density of the human bone. In our opinion, it would be worth to develop a new, more representative material for ballistic which simulates the human bone.

scholarly journals New optical method for analyzing cortical blood flow heterogeneity in small animals: validation of the method

2000 ◽  
Vol 279 (3) ◽  
pp. H1291-H1298 ◽  
Author(s):  
Istvan Schiszler ◽  
Minoru Tomita ◽  
Yasuo Fukuuchi ◽  
Norio Tanahashi ◽  
Koji Inoue
Keyword(s):  
Blood Flow ◽  
Mean Transit Time ◽  
Region Of Interest ◽  
Brain Parenchyma ◽  
Sprague Dawley ◽  
Doppler Flowmetry ◽  
Cranial Window ◽  
Brain Surface ◽  
Fine Glass ◽  
The Brain

In pentobarbital-anesthetized male Sprague-Dawley rats, a small cranial window was trephined, and the cortex was transilluminated with a fine glass fiber inserted into the brain parenchyma. The light intensity at the surface area of 2 × 2 mm was recorded during intracarotid injection of 25 μl of carbon black (CB) solution. The region of interest (ROI) was divided into a 50 × 50 matrix, and the mean transit time of CB transport was calculated in each matrix element. We found rapid transits of CB along the microvasculature, with considerable heterogeneity in the avascular area, and heterogeneous efficiency in autoregulatory capacity in the ROI during hypotension. The method was validated by comparison with laser-Doppler flowmetry. The average mean difference was 0.03 ± 0.05%. Five percent CO2 inhalation increased the flow by 85%, but heterogeneously. We concluded that the technique is exclusively sensitive to indicator transits in a very small area on the brain surface with potential usefulness in detecting regional heterogeneity in blood flow.

scholarly journals Intravital Microreflectometry of Individual Pial Vessels and Capillary Region of Rat

1994 ◽  
Vol 14 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Manabu Watanabe ◽  
Noboru Harada ◽  
Hiroaki Kosaka ◽  
Takeshi Shiga
Keyword(s):  
Oxygen Saturation ◽  
Oxygen Transport ◽  
Progressive Reduction ◽  
Slight Tendency ◽  
Pial Vessels ◽  
Brain Surface ◽  
The Difference ◽  
Spontaneously Breathing ◽  
The Brain

A microscopic reflectance spectrophotometer was constructed to obtain the spectra of single pial vessels and of a region containing only capillaries (capillary region). The difference in the oxygen saturation (So2) of hemoglobin between the regional arteriole and venule [R(A – V)] and that between the regional arteriole or capillaries [R(A – C)] were calculated. The reduction of cytochrome aa3 was also estimated in the capillary region. This method was applied to the brain surface of spontaneously breathing rats subjected to hypoxic and anemic hypoxia. On decreasing the inhaled O2 from 100 to 15%, elevation of R(A – V) and R(A – C) with slight arteriolar dilatation (though statistically not significant) was observed. Below 10% O2 (especially at 4 and 3% O2), the R(A – V) and R(A – C) decreased in spite of significant arteriolar dilatation with progressive reduction of cytochrome aa3, indicating suppression of oxygen transport to mitochondria. In the case of hemodilution down to 37% hematocrit (Ht), elevation of R(A – V) and R(A – C) occurred with a slight tendency toward arteriolar dilatation. Below 32% Ht, the R(A – V) decreased but the R(A – C) remained steady, while reduction of cytochrome aa3 progressed. Altogether, the So2 in the capillary region decreased and the reduction of cytochrome aa3 progressed with the decline of arteriolar O2 supply in both hypoxic and anemic hypoxia.

scholarly journals Application of fluorescent dextrans to the brain surface under constant pressure reveals AQP4-independent solute uptake

2021 ◽  
Vol 153 (8) ◽  
Author(s):  
Alex J. Smith ◽  
Gokhan Akdemir ◽  
Meetu Wadhwa ◽  
Dan Song ◽  
Alan S. Verkman
Keyword(s):  
Constant Pressure ◽  
Water Channel ◽  
Solute Concentration ◽  
External Pressure ◽  
Brain Parenchyma ◽  
Interstitial Space ◽  
Brain Surface ◽  
Solute Uptake ◽  
The Brain

Extracellular solutes in the central nervous system are exchanged between the interstitial fluid, the perivascular compartment, and the cerebrospinal fluid (CSF). The “glymphatic” mechanism proposes that the astrocyte water channel aquaporin-4 (AQP4) is a major determinant of solute transport between the CSF and the interstitial space; however, this is controversial in part because of wide variance in experimental data on interstitial uptake of cisternally injected solutes. Here, we investigated the determinants of solute uptake in brain parenchyma following cisternal injection and reexamined the role of AQP4 using a novel constant-pressure method. In mice, increased cisternal injection rate, which modestly increased intracranial pressure, remarkably increased solute dispersion in the subarachnoid space and uptake in the cortical perivascular compartment. To investigate the role of AQP4 in the absence of confounding variations in pressure and CSF solute concentration over time and space, solutes were applied directly onto the brain surface after durotomy under constant external pressure. Pressure elevation increased solute penetration into the perivascular compartment but had little effect on parenchymal solute uptake. Solute penetration and uptake did not differ significantly between wild-type and AQP4 knockout mice. Our results offer an explanation for the variability in cisternal injection studies and indicate AQP4-independent solute transfer from the CSF to the interstitial space in mouse brain.

Do Complication Rates of Ventricular Drain Placement Differ between Twist Drill and Burr Hole in Acute Hydrocephalus?

2019 ◽  
Vol 80 (04) ◽  
pp. 277-284 ◽  
Author(s):  
Christine Brand ◽  
Andrej Pala ◽  
Wilhelm Kielhorn ◽  
Christian Rainer Wirtz ◽  
Thomas Kapapa
Keyword(s):  
External Ventricular Drainage ◽  
Brain Parenchyma ◽  
Burr Hole ◽  
Acute Subdural Hematoma ◽  
Complication Rates ◽  
Twist Drill ◽  
Acute Hydrocephalus ◽  
Duration Of Surgery ◽  
The Difference ◽  
The Brain

Objective The aim of the study was to compare two techniques for external ventricular drainage (EVD) placement with respect to their complication rates. Methods A retrospective descriptive study was performed to analyze all patients who had undergone EVD implantation for acute hydrocephalus between January 2010 and December 2013 with a focus on surgical technique and rate of complications. The burr hole technique (BHT) was used in one group and the twist-drill technique (TDT) in the other. Particular attention was paid to malposition, hemorrhage, and catheter-associated infection. Results A total of 350 consecutive patients underwent EVD implantation for acute hydrocephalus: BHT was performed in 201 and TDT in 147 of the patients, whereas in two patients the technique used was unknown. The overall infection rate was 6.3% (n = 22). Fourteen patients (4%) in the BHT group developed an infection compared with eight patients (9.5%) in the TDT group (p = 0.154). In 16 (4.5%) of all cases, postoperative computed tomography revealed catheter-induced hemorrhage.In one case (0.3%), surgery was necessary due to acute subdural hematoma. The difference between both techniques was not statistically significant (p = 0.343). In 44 (12.6%) of all cases, the position of the EVD tip was contralateral; in 36 (10.3%) of all cases, the EVD tip was in the brain parenchyma. The rate of malposition was 11.6% (n = 17) in the TDT group and 9.5% (n = 19) in the BHT group (p = 0.078). Conclusion Neither technique showed significantly different numbers in terms of infection, malposition, and hemorrhagic complications. EVD implantation using the TDT is an adequate method compared with BHT. The advantages of TDT are clear: the duration of surgery is shorter, the size of the wound is smaller, and the surgeon is not confined to the operating room.

Video-Assisted Navigation for Adjustment of Image-Guidance Accuracy to Slight Brain Shift

2015 ◽  
Vol 11 (4) ◽  
pp. 504-511 ◽  
Author(s):  
Sven R Kantelhardt ◽  
Angelika Gutenberg ◽  
Axel Neulen ◽  
Naureen Keric ◽  
Mirjam Renovanz ◽  
...  
Keyword(s):  
Surface Relief ◽  
Image Guidance ◽  
Magnetic Resonance Images ◽  
Guidance System ◽  
Brain Shift ◽  
Operating Microscope ◽  
Registration Accuracy ◽  
Brain Surface ◽  
Standard Operating ◽  
The Brain

Abstract BACKGROUND Information supplied by an image-guidance system can be superimposed on the operating microscope oculars or on a screen, generating augmented reality. Recently, the outline of a patient's head and skull, injected in the oculars of a standard operating microscope, has been used to check the registration accuracy of image guidance. OBJECTIVE To propose the use of the brain surface relief and superficial vessels for real-time intraoperative visualization and image-guidance accuracy and for intraoperative adjustment for brain shift. METHODS A commercially available image-guidance system and a standard operating microscope were used. Segmentation of the brain surface and cortical blood vessel relief was performed manually on preoperative computed tomography and magnetic resonance images. The overlay of segmented digital and real operating-microscope images was used to monitor image-guidance accuracy. Adjustment for brain shift was performed by manually matching digital images on real structures. RESULTS Experimental manipulation on a phantom proved that the brain surface relief could be used to restore accuracy if the primary registration shifted. Afterward, the technique was used to assist during surgery of 5 consecutive patients with 7 deep-seated brain tumors. The brain surface relief could be successfully used to monitor registration accuracy after craniotomy and during the whole procedure. If a certain degree of brain shift occurred after craniotomy, the accuracy could be restored in all cases, and corticotomies were correctly centered in all cases. CONCLUSION The proposed method was easy to perform and augmented image-guidance accuracy when operating on small deep-seated lesions.

The betaine-GABA transporter (BGT1, slc6a12) is predominantly expressed in the liver and at lower levels in the kidneys and at the brain surface

2012 ◽  
Vol 302 (3) ◽  
pp. F316-F328 ◽  
Author(s):  
Y. Zhou ◽  
S. Holmseth ◽  
R. Hua ◽  
A. C. Lehre ◽  
A. M. Olofsson ◽  
...  
Keyword(s):  
Plasma Membranes ◽  
Renal Medulla ◽  
Brain Parenchyma ◽  
Ependymal Cells ◽  
Main Role ◽  
Mrna Levels ◽  
Physiological Importance ◽  
Brain Surface ◽  
Negative Controls ◽  
The Brain

The Na+- and Cl−-dependent GABA-betaine transporter (BGT1) has received attention mostly as a protector against osmolarity changes in the kidney and as a potential controller of the neurotransmitter GABA in the brain. Nevertheless, the cellular distribution of BGT1, and its physiological importance, is not fully understood. Here we have quantified mRNA levels using TaqMan real-time PCR, produced a number of BGT1 antibodies, and used these to study BGT1 distribution in mice. BGT1 (protein and mRNA) is predominantly expressed in the liver (sinusoidal hepatocyte plasma membranes) and not in the endothelium. BGT1 is also present in the renal medulla, where it localizes to the basolateral membranes of collecting ducts (particularly at the papilla tip) and the thick ascending limbs of Henle. There is some BGT1 in the leptomeninges, but brain parenchyma, brain blood vessels, ependymal cells, the renal cortex, and the intestine are virtually BGT1 deficient in 1- to 3-mo-old mice. Labeling specificity was assured by processing tissue from BGT1-deficient littermates in parallel as negative controls. Addition of 2.5% sodium chloride to the drinking water for 48 h induced a two- to threefold upregulation of BGT1, tonicity-responsive enhancer binding protein, and sodium- myo-inositol cotransporter 1 (slc5a3) in the renal medulla, but not in the brain and barely in the liver. BGT1-deficient and wild-type mice appeared to tolerate the salt treatment equally well, possibly because betaine is one of several osmolytes. In conclusion, this study suggests that BGT1 plays its main role in the liver, thereby complementing other betaine-transporting carrier proteins (e.g., slc6a20) that are predominantly expressed in the small intestine or kidney rather than the liver.

Cytochemical detection of superoxide in cerebral inflammation and ischemia in vivo

1992 ◽  
Vol 263 (4) ◽  
pp. H1234-H1242 ◽  
Author(s):  
C. D. Kontos ◽  
E. P. Wei ◽  
J. I. Williams ◽  
H. A. Kontos ◽  
J. T. Povlishock
Keyword(s):  
Electron Microscopy ◽  
Ischemia Reperfusion ◽  
Brain Parenchyma ◽  
Brain Surface ◽  
Cerebral Ischemia Reperfusion ◽  
Cerebral Inflammation ◽  
Cytochemical Technique ◽  
The Brain ◽  
Dense Product

We used a cytochemical technique for the detection of superoxide in cerebral inflammation and ischemia-reperfusion in anesthetized cats. The technique is based on the oxidation of Mn2+ to Mn3+ by superoxide; Mn3+, in turn, oxidizes diaminobenzidine. The oxidized diaminobenzidine forms an osmiophilic electron-dense product that is detected by electron microscopy. The reagents, manganese chloride (2 mM) and diaminobenzidine (2 mg/ml), were placed topically on the brain surface of anesthetized cats equipped with cranial windows. Inflammation was induced by topical carrageenan with or without phorbol 12-myristate 13-acetate to activate leukocytes. In inflammation, superoxide was detected in the plasma membrane and in the phagocytic vacuoles of leukocytes. In ischemia-reperfusion, superoxide was identified in the meninges in association with blood vessels. It was located primarily in the extracellular space and occasionally in endothelial and vascular smooth muscle cells. In both inflammation and ischemia, the reaction product was eliminated by superoxide dismutase or by the omission of either manganese or diaminobenzidine. It was unaffected by sodium azide, which inhibits peroxidases. No superoxide was detected in the brain parenchyma. The findings confirm the generation of superoxide is cerebral ischemia-reperfusion and show that it is produced in cerebral vessels.

scholarly journals Generation of CSF1-Independent Ramified Microglia-Like Cells from Leptomeninges In Vitro

Cells ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 24
Author(s):  
Junya Tanaka ◽  
Hisaaki Takahashi ◽  
Hajime Yano ◽  
Hiroshi Nakanishi
Keyword(s):  
Growth Factor Receptor ◽  
Large Cell ◽  
Brain Parenchyma ◽  
Cell Aggregates ◽  
Primary Microglia ◽  
Mixed Glial Culture ◽  
Brain Surface ◽  
Del Rio ◽  
The Brain

Although del Río-Hortega originally reported that leptomeningeal cells are the source of ramified microglia in the developing brain, recent views do not seem to pay much attention to this notion. In this study, in vitro experiments were conducted to determine whether leptomeninges generate ramified microglia. The leptomeninges of neonatal rats containing Iba1+ macrophages were peeled off the brain surface. Leptomeningeal macrophages strongly expressed CD68 and CD163, but microglia in the brain parenchyma did not. Leptomeningeal macrophages expressed epidermal growth factor receptor (EGFR) as revealed by RT-PCR and immunohistochemical staining. Cells obtained from the peeled-off leptomeninges were cultured in a serum-free medium containing EGF, resulting in the formation of large cell aggregates in which many proliferating macrophages were present. In contrast, colony-stimulating factor 1 (CSF1) did not enhance the generation of Iba1+ cells from the leptomeningeal culture. The cell aggregates generated ramified Iba1+ cells in the presence of serum, which express CD68 and CD163 at much lower levels than primary microglia isolated from a mixed glial culture. Therefore, the leptomeningeal-derived cells resembled parenchymal microglia better than primary microglia. This study suggests that microglial progenitors expressing EGFR reside in the leptomeninges and that there is a population of microglia-like cells that grow independently of CSF1.

scholarly journals Hierarchical Iso-Surface Extraction

2002 ◽  
Vol 2 (4) ◽  
pp. 323-329 ◽  
Author(s):  
Ulf Labsik ◽  
Kai Hormann ◽  
Martin Meister ◽  
Gu¨nther Greiner
Keyword(s):  
Data Sets ◽  
Brain Shift ◽  
Volume Data ◽  
Triangle Mesh ◽  
Brain Surface ◽  
Fine Detail ◽  
Novel Approach ◽  
Mesh Decimation ◽  
Archeological Artifacts ◽  
The Brain

The extraction and display of iso-surfaces is a standard method for the visualization of volume data sets. In this paper we present a novel approach that utilizes a hierarchy on both the input and the output data. For the generation of a coarse base mesh, we construct a hierarchy of volumes and extract an iso-surface from the coarsest resolution with a standard Marching Cubes algorithm. We additionally apply a simple mesh decimation algorithm to improve the shape of the triangles. We iteratively fit this mesh to the iso-surface at the finer volume levels. To be able to reconstruct fine detail of the iso-surface we thereby adaptively subdivide the mesh. To evenly distribute the vertices of the triangle mesh over the iso-surface and generate a triangle mesh with evenly shaped triangles, we have integrated a mesh smoothing algorithm into the fitting process. The advantage of this approach is that it generates a mesh with subdivision connectivity which can be utilized by several multiresolution algorithms such as compression and progressive transmission. As applications of our method we show how to reconstruct the surface of archeological artifacts and the reconstruction of the brain surface for the simulation of the brain shift phenomenon.

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