scholarly journals High Precision Bone Cutting by Er: YAG Lasers Might Minimize the Invasiveness of Navigated Brain Biopsies

2022 ◽  
Vol 11 ◽  
Author(s):  
Thanh Tu Ha ◽  
Florian M. Thieringer ◽  
Martin Bammerlin ◽  
Dominik Cordier
Keyword(s):  
Brain Tissue ◽  
Invasive Procedure ◽  
Brain Regions ◽  
Burr Hole ◽  
Lateral Loads ◽  
Bone Surface ◽  
Skull Bone ◽  
Biopsy Needle ◽  
Laser Technology ◽  
Skull Bones

Biopsies of brain tissue are sampled and examined to establish a diagnosis and to plan further treatment, e.g. for brain tumors. The neurosurgical procedure of sampling brain tissue for histologic examination is still a relatively invasive procedure that carries several disadvantages. The “proof of concept”-objective of this study is to answer the question if laser technology might be a potential tool to make brain biopsies less invasive, faster and safer. Laser technology might carry the opportunity to miniaturize the necessary burr hole and also to angulate the burr hole much more tangential in relation to the bone surface in order to take biopsies from brain regions that are usually only difficult and hazardous to access. We examined if it is possible to miniaturize the hole in the skull bone to such a high extent that potentially the laser-created canal itself may guide the biopsy needle with sufficient accuracy. The 2-dimensional, i.e. radial tolerance of the tip of biopsy needles inserted in these canals was measured under defined lateral loads which mimic mechanical forces applied by a surgeon. The canals through the skull bones were planned in angles of 90° (perpendicular) and 45° relative to the bone surface. We created a total of 33 holes with an Er : YAG laser in human skull bones. We could demonstrate that the achievable radial tolerance concerning the guidance of a biopsy needle by a laser created bone canal is within the range of the actual accuracy of a usual navigated device if the canal is at least 4 mm in length. Lateral mechanical loads applied to the biopsy needle had only minor impact on the measurable radial tolerance. Furthermore, in contrast to mechanical drilling systems, laser technology enables the creation of bone canals in pointed angles to the skull bone surface. The latter opens the perspective to sample biopsies in brain areas that are usually not or only hazardous to access.

scholarly journals Biomechanical comparison of concussions with and without a loss of consciousness in elite American football

Neurology ◽  
2018 ◽  
Vol 91 (23 Supplement 1) ◽  
pp. S3.1-S3
Author(s):  
Janie Cournoyer ◽  
Thomas Blaine Hoshizaki
Keyword(s):  
Brain Tissue ◽  
Impact Velocity ◽  
Linear Acceleration ◽  
Brain Regions ◽  
American Football ◽  
Loss Of Consciousness ◽  
Tissue Deformation ◽  
Rotational Acceleration ◽  
Cumulative Strain ◽  
Severity Of Injury

IntroductionLoss of consciousness (LOC) occurs with approximately 8 percent of concussions in professional American football and has been associated with severity of injury (1, 2). However it is unknown how LOC relates to severity of head impact responses. The purpose of this study was to compare the head accelerations and brain tissue deformation between cases of concussions with and without LOC in elite American football to inform prevention strategies.MethodsConcussive injuries with and without LOC from helmet-to-helmet and shoulder collisions as well as falls in elite American football were reconstructed in laboratory using hybrid III headform to obtain peak linear and rotational acceleration and maximum principal strain, cumulative strain damage at 10%, and strain rate metrics in 5 brain regions associated with loss of consciousness.ResultsImpact velocity, peak linear and rotational acceleration were greater in the LOC group than the no LOC group. The brain tissue deformation metrics were greater in the LOC group than the no LOC group. Linear acceleration was most predictive for cases of helmet-to-helmet collisions whereas shoulder collisions were best predicted by rotational acceleration. The best overall predictor was impact velocity.Discussion/conclusionThe presence of a loss of consciousness in concussive impacts is a result of greater magnitude of brain tissue trauma. This was primarily caused by greater impact velocities in head impacts leading to LOC. Rules aiming at mitigating this aspect of the game would decrease the risk of a loss of consciousness in this sport. Each type of events resulted in different values of kinematic data and brain tissue deformation, which suggests that studies evaluating risk of concussions based 1 type of event cannot be generalized.

scholarly journals Top Priorities for Cerebroprotective Studies: A Paradigm Shift

Stroke ◽  
2021 ◽  
Author(s):  
Patrick Lyden ◽  
Alastair Buchan ◽  
Johannes Boltze ◽  
Marc Fisher ◽  
Keyword(s):  
Ischemic Stroke ◽  
Brain Tissue ◽  
Imaging Techniques ◽  
Neurovascular Unit ◽  
Clinical Trial Design ◽  
Clinical Work ◽  
Brain Regions ◽  
Tissue Imaging ◽  
Health Concern ◽  
Stroke Treatment

Despite years of basic research and pioneering clinical work, ischemic stroke remains a major public health concern. Prior STAIR (Stroke Treatment Academic Industry Roundtable) conferences identified both failures of clinical trial design and failures in preclinical assessment in developing putative ischemic stroke treatments. At STAIR XI, participants in workshop no. 1 Top Priorities for Neuroprotection sought to redefine the neuroprotection paradigm and given the paucity of evidence underlying preclinical assessment, offer consensus-based recommendations. STAIR proposes the term brain cytoprotection or cerebroprotection to replace the term neuroprotection when the intention of an investigation is to demonstrate that a new, candidate treatment benefits the entire brain. Although “time is still brain,” tissue imaging techniques have been developed to identify patients with both predicted core injury and penumbral, salvageable brain tissue, regardless of time after stroke symptom onset. STAIR XI workshop participants called this imaging approach a tissue window to select patients for recanalization. Elements of the neurovascular unit show differential vulnerability evolving over differing time scales in different brain regions. STAIR proposes the term target window to suggest therapies that target the different elements of the neurovascular unit at different times. Based on contemporary principles of rigor and transparency, the workshop updated, revised, and enhanced the STAIR preclinical recommendations for developing new treatments in 2 phases: an exploratory qualification phase and a definitive validation phase. For new, putative treatments, investigators should carefully characterize the mechanism of action, the pharmacokinetics/pharmacodynamics, demonstrate target engagement, and confirm penetration through the blood-brain barrier. Before clinical trials, testing of candidate molecules in stroke models could proceed in a comprehensive manner using animals of both sexes and to include significant variables such as age and comorbid conditions. Comprehensive preclinical assessment might include multicenter, collaborative testing, for example, network trials. In the absence of a proven cerebroprotective agent to use as a gold standard, however, it remains speculative whether such comprehensive preclinical assessment can effectively predict clinical outcome.

scholarly journals Neuromediator systems in some brain regions of rats subjected to morphine intoxication

2010 ◽  
Vol 56 (5) ◽  
pp. 562-569
Author(s):  
S.V. Lelevich ◽  
A.A. Novokshonov
Keyword(s):  
Brain Stem ◽  
Brain Tissue ◽  
Brain Regions ◽  
Cerebral Hemispheres ◽  
Serotonin Level ◽  
Chronic Morphine ◽  
Chronic Morphine Intoxication ◽  
System Functioning ◽  
Gaba Content ◽  
The Brain

The content of neuromediators and its metabolites in the cortex of cerebral hemispheres, in thalamus and brain stem was studied under chronic morphine intoxication (7-21 days). The morphine intake during 7-14 days was accompanied by changes of catecholamine system functioning, which was the most pronounced in the thalamus and the brain stem. These changes included increased secretion of dophamine and noradrenaline, their decrease in the brain tissue, and the increased content of their metabolites. The changes of serotonin and GABA content were less pronounced and included a decrease of serotonin level and the increase of the GABA content in different periods of narcotization.

scholarly journals Microglia contribute to the propagation of Aβ into unaffected brain tissue

2021 ◽  
Author(s):  
Paolo d’Errico ◽  
Stephanie Ziegler-Waldkirch ◽  
Vanessa Aires ◽  
Philippe Hoffmann ◽  
Charlotte Mezö ◽  
...  
Keyword(s):  
Brain Tissue ◽  
Amyloid Beta ◽  
In Vivo Imaging ◽  
Brain Regions ◽  
Wild Type

AbstractMicroglia appear activated in the vicinity of amyloid beta (Aβ) plaques, but whether microglia contribute to Aβ propagation into unaffected brain regions remains unknown. Using transplantation of wild-type (WT) neurons, we show that Aβ enters WT grafts, and that this is accompanied by microglia infiltration. Manipulation of microglia function reduced Aβ deposition within grafts. Furthermore, in vivo imaging identified microglia as carriers of Aβ pathology in previously unaffected tissue. Our data thus argue for a hitherto unexplored mechanism of Aβ propagation.

Simulation of Brain Response to Noncontact Impacts Using Coupled Eulerian–Lagrangian Method

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Miao Na ◽  
Timothy J. Beavers ◽  
Abhijit Chandra ◽  
Sarah A. Bentil
Keyword(s):  
Brain Tissue ◽  
Mechanical Response ◽  
Brain Regions ◽  
Von Mises Stress ◽  
Fe Model ◽  
Brain Response ◽  
Fe Method ◽  
Angular Velocities ◽  
Von Mises ◽  
The Brain

Abstract Finite element (FE) method has been widely used for gaining insights into the mechanical response of brain tissue during impacts. In this study, a coupled Eulerian−Lagrangian (CEL) formulation is implemented in impact simulations of a head system to overcome the mesh distortion difficulties due to large deformation in the cerebrospinal fluid (CSF) region and provide a biofidelic model of the interaction between the brain and skull. The head system used in our FE model is constructed from the transverse section of the human brain, with CSF modeled by Eulerian elements. Spring connectors are applied to represent the pia-arachnoid connection between the brain and skull. Validations of the CEL formulation and the FE model are performed using the experimental results. The dynamic response of brain tissue under noncontact impacts and the brain regions susceptible to injury are evaluated based on the intracranial pressure (ICP), maximum principal strain (MPS), and von Mises stress. While tracking the critical MPS location on the brain, higher likelihood of contrecoup injury than coup injury is found when sudden brain−skull motion takes place. The accumulation effect of CSF in the ventricle system, under large relative brain−skull motion, is also identified. The FE results show that adding relative angular velocities, to the translational impact model, not only causes a diffuse high strain area, but also cause the temporal lobes to be susceptible to cerebral contusions since the protecting CSF is prone to be squeezed away at the temporal sites due to the head rotations.

Chemical targeting of voltage sensitive dyes to specific cells and molecules in the brain

2020 ◽  
Author(s):  
Tomas Fiala ◽  
Jihang Wang ◽  
Matthew Dunn ◽  
Peter Šebej ◽  
Se Joon Choi ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Brain Tissue ◽  
Fluorescent Dyes ◽  
Brain Slices ◽  
Brain Regions ◽  
Expression Levels ◽  
Specific Targeting ◽  
The Impact ◽  
Voltage Sensitive Dyes ◽  
The Brain

Voltage sensitive fluorescent dyes (VSDs) are important tools for probing signal transduction in neurons and other excitable cells. These sensors, rendered highly lipophilic to anchor the conjugated pi-wire molecular framework in the membrane, offer several favorable functional parameters including fast response kinetics and high sensitivity to membrane potential changes. The impact of VSDs has, however, been limited due to the lack of cell-specific targeting methods in brain tissue or living animals. We address this key challenge by introducing a non-genetic molecular platform for cell- and molecule-specific targeting of synthetic voltage sensitive dyes in the brain. We employ a dextran polymer particle to overcome the inherent lipophilicity of voltage sensitive dyes by dynamic encapsulation, and high-affinity ligands to target the construct to specific neuronal cells utilizing only native components of the neurotransmission machinery at physiological expression levels. Dichloropane, a monoamine transporter ligand, enables targeting of dense dopaminergic axons in the mouse striatum and sparse noradrenergic axons in the mouse cortex in acute brain slices. PFQX in conjunction with ligand-directed acyl imidazole chemistry enables covalent labeling of AMPA-type glutamate receptors in the same brain regions. Probe variants bearing either a classical electrochromic ANEP dye or state-of-the-art VoltageFluor-type dye respond to membrane potential changes in a similar manner to the parent dyes, as shown by whole-cell patch recording. We demonstrate the feasibility of optical voltage recording with our probes in brain tissue with one-photon and two-photon fluorescence microscopy and define the signal limits of optical voltage imaging with synthetic sensors under a low photon budget determined by the native expression levels of the target proteins. We envision that modularity of our platform will enable its application to a variety of molecular targets and sensors, as well as lipophilic drugs and signaling modulators. This work demonstrates the feasibility of a chemical targeting approach and expands the possibilities of cell-specific imaging and pharmacology.

The Study of Cerebral Blood Flow Variations during Brain Metastasis Radiotherapy

2021 ◽  
Author(s):  
Chuanke Hou ◽  
Guanzhong Gong ◽  
Lizhen Wang ◽  
Ya Su ◽  
Jie Lu ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Brain Tissue ◽  
Critical Factor ◽  
Brain Regions ◽  
Normal Brain ◽  
Peritumoral Edema ◽  
Normal Brain Tissue ◽  
Cross Sectional ◽  
Contrast Enhanced

Purpose: To investigate the cerebral blood flow (CBF) variations during brain metastases (BMs) radiotherapy (RT) applying with MR 3D-arterial spin labeling (ASL). Materials and Methods: A total of 26 BMs patients with 54 tumors were retrospectively enrolled. MR examinations were performed before and during RT (30-50 Gy) with a total dose of 36-60 Gy (12-30 fractions) including contrast-enhanced T1-weighted, T2 Flair and 3D-ASL images. The relationship between CBF changes and the largest cross-sectional area changes in BMs was investigated. And CBF changes in BMs, normal brain tissue, and peritumoral edema areas were analyzed under different dose gradients that was divided into 10 Gy intervals. Results: The largest cross-sectional areas and CBF of 54 BMs decreased by 26.46% and 29.64% respectively during RT (P<0.05), but there was no correlation between the two changes (P>0.05). The rates of CBF decrease in BMs were 33.75%, 24.61% and 27.55% at 30-40, 40-50 and >50 Gy, respectively (P<0.05). In normal brain tissue with dose gradients of 0-10, 10-20, 20-30, 30-40, 40-50 and > 50 Gy, the CBF decreased by 7.65%, 11.12%, 18.42%, 20.23%, 19.79% and 17.89%, respectively (P <0.05). The CBF decreases reached a maximum at 30-40 Gy in normal brain tissue as well as BMs. In contrast, the CBF decreases of peritumoral edema areas increased as the dose gradients increased. Moreover, the CBF changes of BMs were more notable than those in normal brain tissue and peritumoral edema areas. Conclusion: CBF changes can be feasibly assessed in different brain regions during RT based on 3D-ASL. The changes should be considered as a critical factor to determine the personal radiation dose for BMs, normal brain tissue and peritumoral edema areas.

Immumohistochemical Detection and Localization of Prion Protein in Brain Tissue of Sheep With Natural Scrapie

1995 ◽  
Vol 32 (3) ◽  
pp. 299-308 ◽  
Author(s):  
L. J. M. van Keulen ◽  
B. E. C. Schreuder ◽  
R. H. Meloen ◽  
M. Poelen-van den Berg ◽  
G. Mooij-Harkes ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Brain Tissue ◽  
Prion Protein ◽  
Medulla Oblongata ◽  
Brain Regions ◽  
Cellular Prion Protein ◽  
Immunohistochemical Method ◽  
Tissue Sections ◽  
Natural Scrapie ◽  
Detection And Localization

A converted form of the normal cellular prion protein (PrP) accumulates in the brains of sheep with scrapie. We describe an immunohistochemical method for identifying scrapie-associated PrP (PrPSc) in periodate-lysine-paraformaldehyde-fixed brain tissue, which provides adequate preservation of tissue morphology. After pretreatment of tissue sections with formic acid and hydrated autoclaving, we located PrPSc in the brains of 50 sheep with natural scrapie by use of antipeptide antisera raised against ovine PrP. No PrP was seen in 20 sheep without histopathologic signs of scrapie. PrP80 that did not stain for amyloid was present in the cytoplasm and at the cell membrane of both neurons and astrocytes. Large amounts of PrPSc were seen at the cell membrane of neurons in the medulla oblongata and pons, whereas PrPSc accumulated at the cell membrane of astrocytes of the glial limitans in all brain regions. PrPSc that stained for amyloid was located in the walls of blood vessels and perivascularly in the brains of 32 (64%) of 50 sheep, mainly in the thalamus and never in the pons or medulla oblongata. No apparent topographic relationship existed between PrPSc that stained for amyloid and PrPSc accumulation associated with neurons or astrocytes. In all scrapie-affected sheep, PrPSc was present in brain regions with vacuolation, but it could also be detected in regions with minimal or no vacuolation. We conclude that the immunohistochemical detection of PrP can be an important confirmative test in scrapie diagnosis.

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