Dissecação anatômica como estratégia para o estudo do sistema neural em fetos humanos / Anatomic dissection as a strategy for the study of the neural system in fetuses / Disección anatómica como estrategia para el estudio del sistema neural en fetos

Esse trabalho busca relatar o processo de confecção de peças anatômicas para o ensino da anatomia humana a partir de material cadavérico fetal. Os discentes do curso de medicina da Universidade Federal do Paraná (UFPR) ­ Campus Toledo participaram do programa de voluntariado acadêmico e deram atenção especial aos aspectos técnicos do processo de dissecação, bem como a experiência subjetiva desse procedimento como ferramenta de aprendizado ativo. O procedimento foi realizado na sala de preparação de cadáver da UFPR ­ Campus Toledo, utilizando instrumental de dissecação e cadáveres humanos fetais com 20, 17 e 14 semanas de idade gestacional, direcionado de modo a expor as partes constituintes do sistema neural. Foram confeccionadas peças de cérebro, cerebelo, tronco encefálico, medula espinal, nervos espinais e suas estruturas associadas. Os voluntários envolvidos foram capazes de produzir material de estudo de qualidade através da dissecação e fortalecer seu conhecimento em anatomia humana e aptidão manual. Também foi dada atenção à importância e às limitações do processo de dissecação como estratégia de aprendizado em cursos da área de saúde. pôde ser observado que a dissecação pode fazer parte de uma formação completa e bem estruturada dos discentes, que por sua vez irão integrar a sociedade e a academia. Além disso, a exposição da topografia neural fetal pode servir de referencial para posteriores estudos que venham a utilizar essas informações.

This work aims to report the confection process of anatomic pieces for teaching human anatomy from fetal cadaveric material. The students of the medicine course of Universidade Federal do Paraná (UFPR) ­ Campus Toledo, took part in the academic volunteer program and paid special attention to the technical aspects of the dissection process, as well as the subjective experience of this procedure as an active learning tool. The procedure was performed at the cadaver preparation room of the UFPR ­ Campus Toledo, using dissection tools and human fetal corpses of 20, 17 and 14 weeks of gestational ages, directed so as to expose the constituent parts of the neural system. Pieces of the brain, cerebellum, brainstem, spinal cord, spinal nerves, and its associated structures were made. The involved voluntaries were able to produce quality study material through dissection, and strengthen their knowledge in human anatomy and manual skill. Attention was also given to the importance and limitations of the dissection process as a learning strategy in health courses. it was observed that dissection can be part of a complete and well-structured training of students, who in turn will integrate society and academia. In addition, the exposure of fetal neural topography can serve as a reference for further studies that use this information

Este trabajo tiene como objetivo relatar el proceso de confección de piezas anatómicas para la enseñanza de la anatomía humana a partir de material cadavérico fetal. Los alumnos del curso de medicina de la Universidade Federal do Paraná (UFPR) - Campus Toledo, participaron del programa de voluntariado académico y prestaron especial atención a los aspectos técnicos del proceso de disección, así como a la vivencia subjetiva de este procedimiento como herramienta de aprendizaje activo. El procedimiento fue realizado en la sala de preparación de cadáveres de la UFPR - Campus Toledo, utilizando herramientas de disección y cadáveres de fetos humanos de 20, 17 y 14 semanas de edad gestacional, dirigidos de forma a exponer las partes constitutivas del sistema neural. Se realizaron piezas del cerebro, cerebelo, tronco encefálico, médula espinal, nervios espinales y sus estructuras asociadas. Los voluntarios participantes pudieron elaborar material de estudio de calidad mediante la disección y reforzar sus conocimientos de anatomía humana y habilidad manual. También se prestó atención a la importancia y las limitaciones del proceso de disección como estrategia de aprendizaje en los cursos de salud. Se observó que la disección puede formar parte de una formación completa y bien estructurada de los estudiantes, que a su vez integrarán la sociedad y el mundo académico. Además, la exposición de la topografía neural fetal puede servir de referencia para estudios posteriores que utilicen esta información.

Intraspinal injection of adeno-associated viruses into the adult mouse spinal cord.

Genetic dissection of neural circuits has been accelerated by recent advances in viral-based vectors. This protocol describes an effective approach to performing intraspinal injections of adeno-associated viruses, which can be used to label, manipulate, and monitor spinal and supraspinal neurons. By avoiding invasive laminectomies and restrictive spinal-clamping and by adopting injectable anaesthetics and tough quartz glass micropipettes, our protocol presents a time-saving and efficient approach for genetic manipulation of neural circuits nucleated in the spinal cord. For complete details on the use and execution of this protocol, please refer to Sathyamurthy et al. (2020).

Spinal Cord Anatomy and Localization.

PURPOSE OF REVIEW: This article focuses on clinically relevant teaching points in spinal anatomy and localizing the lesion in myelopathy. RECENT FINDINGS: The principles underlying spinal cord lesion localization are well established, but improvements in MRI and the discovery of pathologic antibodies associated with causes of transverse myelitis distinct from multiple sclerosis, such as aquaporin-4 IgG and myelin oligodendrocyte glycoprotein IgG, have assisted in diagnosis. SUMMARY: The spinal cord has a highly organized neuroanatomy of ascending and descending tracts that convey sensory, motor, and autonomic information. Using integration of clues from the patient's history and neurologic examination, the effective clinician can distinguish spinal cord from peripheral nerve or brain pathology, often determine the level and parts of the spinal cord affected by a lesion, and focus on a likely diagnosis. The advent of MRI of the spine has revolutionized investigation of spinal cord disorders, but an important place for strong clinical acumen still exists in assessing the patient with a myelopathy.

Transforaminal intrathecal delivery of nusinersen for older children and adults with spinal muscular atrophy and complex spinal anatomy: an analysis of 200 consecutive injections.

BACKGROUND: Nusinersen is the only approved treatment for all spinal muscular atrophy (SMA) subtypes and is delivered intrathecally. Distorted spinal anatomy and instrumentation preclude standard approaches for intrathecal access, necessitating alternative techniques for delivery. The purpose of this study is to report technical success and adverse events of transforaminal intrathecal delivery of nusinersen. METHODS: 28 patients, mean age 24.1±9.8 years (range 10.0-51.0 years), with intermediate or late onset SMA, underwent a combined 200 transforaminal nusinersen injections. All patients had osseous fusion or spinal instrumentation precluding standard posterior access routes. Patients who underwent nusinersen injections using a technique other than transforaminal lumbar puncture (n=113) were excluded. Technical success, adverse events (AEs) and radiation exposure were recorded. RESULTS: 200 (100%) procedures were technically successful; 6 (3%) required a second level of attempt for access. 187 (93.5%) interventions were completed using cone beam computed tomography (CBCT) with two-axis fluoroscopic navigational overlay. 13 (6.5%) procedures were performed with fluoroscopic-guidance only at subsequent sessions. There were 8 (4.0%) mild AEs and 2 (0.5%) severe AEs; one patient received antibiotics for possible traversal of the large bowel but did not develop meningitis, and one patient developed aseptic meningitis. Mean air kerma was 74.5±161.3 mGy (range 5.2-1693.0 mGy). CONCLUSION: Transforaminal intrathecal delivery of nusinersen is feasible and safe for gaining access in patients with distorted spinal anatomy. The use of CBCT delineates anatomy and optimizes needle trajectory during the initial encounter, and may be used selectively for subsequent procedures.

Distribution and chemical coding of phoenixin-immunoreactive nerve structures in the spinal cord of the pig.

Phoenixin (PNX) is a newly described peptide found in both neural and non-neural tissues. Until now, no attempts have been made to investigate the expression of PNX in the nervous system of animals other than laboratory rodents, in which an enzyme immunoassay revealed the highest quantity of the substance in the spinal cord. Since the domestic pig, due to its anatomical and histological resemblance to humans, is often used as an animal model in biomedical investigations, the present study was designed to examine PNX-immunoreactivity in the spinal cords of female pigs (n=5). The spinal cords were dissected and divided into the cervical, thoracic, lumbar, sacral and coccygeal segments, which were sectioned transversally into 10-µm-thick serial sections. The sections from each spinal cord segment were processed for double-labelling immunohistochemistry using antibodies against PNX in a mixture with those against calcitonin gene-related peptide (CGRP), substance P (SP) or choline acetyltransferase (CHAT). The PNX-immunoreactivity had a similar distribution in the grey matter of all the spinal cord sections examined and was mainly observed in varicose nerve fibres (NF) that formed a dense plexus in laminae I and II of the dorsal horn. Nearly all of the PNX-immunoreactive NF stained also for CGRP or SP and, interestingly, many of them were CHAT-positive. The present study has provided for the first time the detailed information on the arrangement and chemical features of nerve structures expressing PNX-immunoreactivity in the spinal cord of a large mammal. The exact function of PNX in the spinal cord is not known yet. However, the distribution pattern and immunohistochemical characteristics of PNX-IR NF clearly suggest that this peptite most likely plays a role in spinal noxious signalling.

Autoradiography and inmmunolabeling suggests that lizard blastema contains arginase-positive M2-like macrophages that may support tail regeneration.

BACKGROUND: The regenerating blastema of the tail in the lizard Podarcis muralis contains numerous macrophages among the prevalent mesenchymal cells. Some macrophages are phagocytic but others are devoid of phagosomes suggesting that they have other roles aside phagocytosis. METHODS: The presence of healing macrophages (M2-like) has been tested using autoradiographic, immunohistochemical and ultrastructural studies. RESULTS: Autoradiography shows an uptake of tritiated arginine in sparse cells of the blastema and in the regenerating epidermis. Bioinformatics analysis suggests that epitopes for arginase-1 and -2, recognized by the employed antibody, are present in lizards. Immunofluorescence shows sparse arginase immunopositive macrophages in the blastema and few macrophages also in the apical wound epidermis. The ultrastructural study shows that macrophages contain dense secretory granules, most likely inactive lysosomes, and small cytoplasmic pale vesicles. Some of the small vesicles are arginase-positive while immunolabeling is very diffuse in the macrophage cytoplasm. CONCLUSIONS: The presence of cells incorporating arginine and of arginase 1-positive cells suggests that M2-like macrophages are present among mesenchymal and epidermal cells of the regenerative tail blastema. M2-like macrophages may promote tail regeneration differently from the numerous pro-inflammatory macrophages previously detected in the scarring limb. The presence of M2-like macrophages in addition to hyaluronate, support the hypothesis that the regenerative blastema of the tail in lizards is an immuno-privileged organ where cell proliferation and growth occur without degenerating in a tumorigenic outgrowth.

Capturing instructive cues of tissue microenvironment by silica bioreplication.

Cells in tissues are enveloped by an instructive niche made of the extracellular matrix. These instructive niches contain three general types of information: topographical, biochemical and mechanical. While the combined effects of these three factors are widely studied, the functions of each individual one has not been systematically characterised, because it is impossible to alter a single factor in a tissue microenvironment without simultaneously affecting the other two. Silica BioReplication (SBR) is a process that converts biological samples into silica, faithfully preserving the original topography at the nano-scale. We explored the use of this technique to generate inorganic replicas of intact mammalian tissues, including tendon, cartilage, skeletal muscle and spinal cord. Scanning electron and atomic force microscopy showed that the resulting replicas accurately preserved the three-dimensional ultrastructure of each tissue, while all biochemical components were eradicated by calcination. Such properties allowed the uncoupling the topographical information of a tissue microenvironment from its biochemical and mechanical components. Here, we showed that human mesenchymal stem cells (MSC) cultured on the replicas of different tissues displayed vastly different morphology and focal adhesions, suggesting that the topography of the tissue microenvironment captured by SBR could profoundly affect MSC biology. MSC cultured on tendon replica elongated and expressed tenocytes marker, while MSC on the spinal cord replica developed into spheroids that resembled neurospheres, in morphology and in the expression of neurosphere markers, and could be further differentiated into neuron-like cells. This study reveals the significance of topographical cues in a cell niche, as tissue-specific topography was sufficient in initiating and directing differentiation of MSC, despite the absence of any biochemical signals. SBR is a convenient and versatile method for capturing this topographical information, facilitating the functional characterisation of cell niches. STATEMENT OF SIGNIFICANCE: Various studies have shown that three major factors, topographical, biochemical and mechanical, in a tissue microenvironment (TME) are essential for cellular homeostasis and functions. Current experimental models are too simplistic to represent the complexity of the TME, hindering the detailed understanding of its functions. In particular, the importance each factor in a tissue microenvironment have not been individually characterised, because it is challenging to alter one of these factors without simultaneously affecting the other two. Silica bioreplication (SBR) is a process that converts biological samples into silica replicas with high structural fidelity. SBR is a convenient and versatile method for capturing this topographical information on to a biologically inert material, allowing the functional characterisation of the architecture of a TME.

Evaluation and management of cauda equina syndrome in the emergency department.

BACKGROUND: Cauda equina syndrome (CES) may be a devastating disease with the potential for significant patient morbidity. It is essential for emergency clinicians to be aware of how to effectively diagnose and manage this condition. OBJECTIVE: This article provides a narrative review of the diagnosis and management of CES for the emergency clinician. DISCUSSION: Cauda equina syndrome is a rare but emergent condition associated with back pain. It can result in severe morbidity and can be due to a variety of causes, most commonly vertebral disc protrusion. Diagnosis is often delayed, which may result in a poor prognosis. Red flags and findings consistent with CES include bilateral neurogenic sciatica, reduced perineal sensation, altered bladder function leading to painless urinary retention, loss of anal tone, and loss of sexual function. In isolation, history and examination findings demonstrate poor sensitivity. Symptoms may occur either suddenly or gradually, and most patients do not present with all of these symptoms. Postvoid bladder volume assessments can assist in the evaluation, but the diagnosis typically involves magnetic resonance imaging (MRI) or computed tomography myelography if MRI is not available. Treatment relies upon surgical consultation and operative intervention for decompression. CONCLUSION: Cauda equina syndrome can be a difficult diagnosis. However, knowledge of the history and examination findings, imaging, and treatment can assist the emergency clinician in optimizing management of this condition.

The Anatomy of the Sigmoid-Transverse Junction According to the Tentorial Angle.

Dural sinuses have critical importance during intracranial approaches. Detailed anatomical knowledge of the dural sinuses is crucial for surgeons to reduce unexpected venous bleeding. The aim of this study was to investigate anatomical relation of sigmoid sinus and tentorium cerebelli according to clinically palpable landmarks and cranial morphometry. The authors evaluated 222 individuals' (94 women, 128 men) 3-dimensional computed tomography angiograms, retrospectively. The authors also studied on 12 mid-sagittal cut dried hemiskulls and 8 formalin fixed cadaver heads hemisected midsagitally. All measurements were completed using Osirix-Lite version 9 software. Craniometrical values were measured to define cranium morphology. Furthermore, level of the sigmoid sinus according to asterion and tentorial angle were evaluated in detail. Our results demonstrated that there were significant differences between parameters and genders, except vertical angle of the tentorium cerebelli. Distance between asterion and sigmoid sinus was statistically different between right and left sides in favor of the left side. This also varied depending on the position of the sigmoid sinus, as well. Only transverse angle between the upper point of external acoustic meatus and asterion demonstrated a significant correlation with age. This study evaluated the detailed 3D anatomy of sigmoid sinus and tentorium cerebelli related with the cranium morphology. Determining to sigmoid sinus anatomy according to clinically palpable landmarks has advantages for setting surgical protocols and reducing to unexpected injuries while surgery to these structures.

Skeletopy of the medullary cone in Sapajus apella: Clinical implications in epidural anesthesia / Esqueletopia do cone medular em Sapajus apella: Implicações clínicas na anestesia epidural

This work aimed to describe the skeletopy of the medullary cone of the capuchin monkey (Sapajus apella) and to lay morphological foundations to propose a route of administration for epidural anesthesia. We used five females adults S.apella, and dissected them to study their medullary cone. The fixated animals were dissected, a skin incision was made from the dorsal median line, epaxial musculature and vertebral arcs was removed to expose the spinal cord, individualizing the medullary cone and the lumbar intumescence. The base of S. apella medullary cone was located near the L5 vertebra and the apex near S3, the structure was 4.5 cm in average. The evaluated specimens presented five lumbar and four sacral vertebrae. We concluded that the positioning of S. apella medullary cone is caudally than in other species, suggesting that the most appropriate location for epidural anesthetic procedures is the sacrocaudal region.

Este estudo visa descrever a esqueletopia do cone medular em macaco prego (Sapajus apella), com a intenção de estabelecer bases morfológicas para prestar o apoio à implementação de procedimentos anestésicos e outros procedimentos de rotina clínica-cirúrgica veterinária, dada a crescente importância do papel do veterinário na saúde dos animais selvagens. Cinco S. apella adultos fêmeas foram utilizadas neste trabalho e dissecados para o estudo do cone medular. Os animais fixados foram dissecados, foi feita uma incisão na pele na linha média dorsal, a musculatura epaxial e os arcos vertebrais foram removidos para exposição da medula espinhal, individualizando o cone medular e a intumescência lombar. A base do cone medular do S. apella foi observada na altura da vértebra L5 com o ápice em S3, com comprimento médio de 4,5 cm. Os espécimes avaliados apresentaram cinco vértebras lombares e quatro sacrais. Conclui-se que o posicionamento do cone medular do S. apella é mais caudal em relação às outras espécies. Por conseguinte, é sugerido que o local mais apropriado para o procedimento anestésico peridural é a sacrocaudal região.

Anatomic conditions for bypass surgery between rostral (T7-T9) and caudal (L2, L4, S1) ventral roots to treat paralysis after spinal cord injury.

Severe spinal cord injuries cause permanent neurological deficits and are still considered as inaccessible to efficient therapy. Injured spinal cord axons are unable to spontaneously regenerate. Re-establishing functional activity especially in the lower limbs by reinnervation of the caudal infra-lesional territories might represent an effective therapeutic strategy. Numerous surgical neurotizations have been developed to bridge the spinal cord lesion site and connect the intact supra-lesional portions of the spinal cord to peripheral nerves (spinal nerves, intercostal nerves) and muscles. The major disadvantage of these techniques is the increased hypersensitivity, spasticity and pathologic pain in the spinal cord injured patients, which occur due to the vigorous sprouting of injured afferent sensory fibers after reconstructive surgery. Using micro-surgical instruments and an operation microscope we performed detailed anatomical preparation of the vertebral canal and its content in five human cadavers. Our observations allow us to put forward the possibility to develop a more precise surgical approach, the so called "ventral root bypass" that avoids lesion of the dorsal roots and eliminates sensitivity complications. The proposed kind of neurotization has been neither used, nor put forward. The general opinion is that radix ventralis and radix dorsalis unite to form the spinal nerve inside the dural sac. This assumption is not accurate, because both radices leave the dural sac separately. This neglected anatomical feature allows a reliable intravertebral exposure of the dura-mater ensheathed ventral roots and their damage-preventing end-to-side neurorrhaphy by interpositional nerve grafts.

Topography of the medullary cone of the feline night monkey: Clinical implications in epidural anesthesia / Topografia do cone medular do macaco-da-noite: auxiliando a abordagem peridural

Feline night monkey (Aotus azarae infulatus) is an arboreal primate that sleeps during the day hidden among branches of trees, leaving its hideout after nightfall. Little is known about the morphology of these animals, which leads to some difficulty in clinical and surgical approaches, as there has been substantial growth in the veterinarian's role in maintaining the health and well-being of wildlife. Thus, we sought to investigate the topography and morphometry of the medullary cone, a small portion of the nervous system of the feline night monkey, which is of paramount importance in approaches for epidural anesthesia. Specimens from five young females were used, each with eight lumbar vertebrae, three sacral vertebrae, and a medullary cone with an average length of 7.5 cm, located between L5 and S3. Based on this finding, we suggest that a probable site for the application of epidural anesthesia is the space between S3 and Cc1.

O macaco-da-noite (Aotus azarae infulatus) é um animal arborícola que dorme durante o dia escondido entre os ramos, saindo do esconderijo após o anoitecer. Pouco se sabe sobre a morfologia destes animais, o que gera certa dificuldade nas abordagens clínico-cirúrgicas, uma vez que cresce substancialmente o papel do médico veterinário nas questões de saúde e bem-estar de animais selvagens. Visando contribuir com esses profissionais, buscou-se investigar a topografia e morfometria de uma pequena porção do sistema nervoso do macaco-da-noite, o cone medular, que é de suma importância nas abordagens quanto à anestesia peridural. Foram utilizados cinco espécimes fêmeas, jovens, de macaco-da-noite, que apresentavam oito vértebras lombares e três vértebras sacrais, e cone medular possuindo em média de 7,5 cm de comprimento, localizando-se entre L5 e S3. Este achado nos leva a sugerir como sítio provável para a aplicação de anestesia epidural, o espaço entre S3 e Cc1.

Effects of Tualang honey in modulating nociceptive responses at the spinal cord in offspring of prenatally stressed rats.

OBJECTIVE: This study was done to determine whether Tualang honey could prevent the altered nociceptive behaviour, with its associated changes of oxidative stress markers and morphology of the spinal cord, among the offspring of prenatally stressed rats. METHODS: Pregnant rats were divided into three groups: control, stress, and stress treated with Tualang honey. The stress and stress treated with Tualang honey groups were subjected to restraint stress from day 11 of pregnancy until delivery. Ten week old male offspring (n = 9 from each group) were given formalin injection and their nociceptive behaviours were recorded. After 2 h, the rats were sacrificed, and their spinal cords were removed to assess oxidative stress activity and morphology. Nociceptive behaviour was analysed using repeated measures analysis of variance (ANOVA), while the levels of oxidative stress parameters and number of Nissl-stained neurons were analysed using a one-way ANOVA. RESULTS: This study demonstrated that prenatal stress was associated with increased nociceptive behaviour, changes in the oxidative stress parameters and morphology of the spinal cord of offspring exposed to prenatal stress; administration of Tualang honey reduced the alteration of these parameters. CONCLUSION: This study provides a preliminary understanding of the beneficial effects of Tualang honey against the changes in oxidative stress and neuronal damage in the spinal cord of the offspring of prenatally stressed rats.

Anatomical Variation in Morphometry and Morphology of the Foramen Magnum and Occipital Condyle in Dried Adult Skulls.

BACKGROUND: The foramen magnum (FM) is the largest opening and is outlet through which medulla oblongata and spinal cord along with meninges, vertebral arteries, anterior and posterior spinal arteries, tectorial membrane, alar ligaments, and spinal branch of the accessory nerve. Occipital condyle (OC) is an important part of craniovertebral or craniocervical junction located anterolaterally on either side of the FM. The objective of the study was to assess variations of FM and OC in Ethiopian dried adult skulls. METHODS: Observation-based descriptive study design was employed. The study was undertaken in 54 FM and 108 OC of 54 adult Ethiopian skulls. The morphometry of FM and OC were determined using a sliding vernier caliper. RESULTS: The mean values of anteroposterior and transverse diameters of the FM were 35.19 and 30.17 mm, respectively, and the mean area of the FM was 853.36 mm. The shapes of FM were determined as round in 22.2%, oval in 18.5%, egg like in 20.4%, triangular in 3.7%, pentagonal in 11.1%, hexagonal in 7.4%, irregular in 13%, and rectangular in 3.7% of the cases. The mean length of right and left OC was 25.69 and 26.96 mm, respectively, and the mean widths of the right and left OC were 12.76 and 13.04 mm, respectively. CONCLUSION: Our study identified various shapes of FM and diameter. The anteroposterior diameter is greater than the transverse diameter. The morphometric study of OC confirmed the length of left side is significantly greater than the right side.

Evidencia neuroanatómica del transporte del virus de la rabia por la vía propioespinal de la médula espinal de ratones / Neuroanatomical evidence of the transport of the rabies virus through the propriospinal tract in the spinal cord of mice

Resumen Introducción. Es escasa la información sobre los detalles neuroanatómicos del transporte del virus de la rabia en su ascenso por la médula espinal. Objetivos. Identificar la ruta neuroanatómica de diseminación del virus de la rabia en cada uno de los niveles de la médula espinal de ratón, después de ser inoculado por vía intramuscular. Materiales y métodos. Se inocularon ratones en los músculos isquiotibiales, con virus de la rabia. A partir de las 24 horas después de la inoculación, cada ocho horas se sacrificaron cinco animales por perfusión con paraformaldehído, se les extrajo la médula espinal y se hicieron cortes transversales en los niveles lumbosacro, torácico y cervical. Estos se procesaron mediante inmunohistoquímica para detectar antígenos virales. Resultados. Los primeros antígenos de la rabia se observaron como partículas agregadas, en la médula espinal lumbar, a las 24 horas después de la inoculación, dentro del asta ventral ipsilateral a la extremidad inoculada. A las 32 horas después de la inoculación, se hicieron visibles las primeras motoneuronas inmunorreactivas al virus. A las 40 horas después de la inoculación, se revelaron las primeras neuronas inmunorreactivas en la médula torácica, localizadas en la lámina 8 y, a las 48 horas después de la inoculación en la médula cervical, también en la lámina 8. A las 56 horas después de la inoculación, el virus se había diseminado por toda la médula espinal pero los animales aún no revelaban signos de la enfermedad. Conclusión. En el modelo de ratón aquí utilizado, el virus de la rabia ingresó a la médula espinal por las motoneuronas y, probablemente, utilizó la vía propioespinal descendente para su transporte axonal retrógrado hasta el encéfalo.

Abstract Introduction: Information about the neuroanatomical details of the ascendant transport of the rabies virus through the spinal cord is scarce. Objective: To identify the neuroanatomical route of dissemination of the rabies virus at each of the levels of the spinal cord of mice after being inoculated intramuscularly. Materials and methods: Mice were inoculated with the rabies virus in the hamstrings. After 24 hours post-inoculation, every eight hours, five animals were sacrificed by perfusion with paraformaldehyde. Then, the spinal cord was removed, and transverse cuts were made at the lumbosacral, thoracic, and cervical levels. These were processed by immunohistochemistry for the detection of viral antigens. Results: The first antigens of rabies were observed as aggregated particles in the lumbar spinal cord at 24 hours post-inoculation, within the ventral horn in the same side of the inoculated limb. At 32 hours post inoculation the first motoneurons immunoreactive to the virus became visible. At 40 hours post-inoculation the first immunoreactive neurons were revealed in the thoracic level, located on lamina 8 and at 48 hours post-inoculation in the cervical cord, also on lamina 8. At 56 hours post-inoculation the virus had spread throughout the spinal cord, but the animals still did not show signs of the disease. Conclusion: In the mouse model we used, the rabies virus entered the spinal cord through the motoneurons and probably used the descending propriospinal pathway for its retrograde axonal transport to the encephalus.

Spinal Cord Disorders: Myelopathy.

Myelopathy is a clinical diagnosis based on symptoms and physical examination findings. Laboratories and imaging, particularly with magnetic resonance imaging, can suggest a cause. Compressive myelopathy from degenerative disease of the vertebral column is the most common cause of myelopathy in older adults and should be screened for first in most cases. There are many other causes of myelopathy, including infectious, immune-mediated, nutritional, vascular, and neoplastic etiologies.

Biomaterials for revascularization and immunomodulation after spinal cord injury.

Spinal cord injury (SCI) causes immediate damage to the nervous tissue accompanied by loss of motor and sensory function. The limited self-repair competence of injured nervous tissue underscores the need for reparative interventions to recover function after SCI. The vasculature of the spinal cord plays a crucial role in SCI and repair. Ruptured and sheared blood vessels in the injury epicenter and blood vessels with a breached blood-spinal cord barrier (BSCB) in the surrounding tissue cause bleeding and inflammation, which contribute to the overall tissue damage. The insufficient formation of new functional vasculature in and near the injury impedes endogenous tissue repair and limits the prospect of repair approaches. Limiting the loss of blood vessels, stabilizing the BSCB, and promoting the formation of new blood vessels are therapeutic targets for spinal cord repair. Inflammation is an integral part of injury-mediated vascular damage, which has deleterious and reparative consequences. Inflammation and the formation of new blood vessels are intricately interwoven. Biomaterials can be effectively used for promoting and guiding blood vessel formation or modulating the inflammatory response after SCI, thereby governing the extent of damage and the success of reparative interventions. This review deals with the vasculature after SCI, the reciprocal interactions between inflammation and blood vessel formation, and the potential of biomaterials to support revascularization and immunomodulation in damaged spinal cord nervous tissue.

Cord Topographical Anatomy and its Role in Evaluating Intramedullary Lesions.

Intramedullary spinal lesions present a wide differential diagnosis including infectious, inflammatory, traumatic, ischemic, benign, or malignant neoplastic etiologies. Using knowledge of anatomy and physiology within the spinal cord, many similar appearing entities can be parsed into a prioritized differential. The purpose of this article is to review anatomy and pathophysiology of the spinal cord, with subsequent discussion of how this knowledge can be used to differentiate several similar appearing intramedullary pathologic processes. Discussion includes the pathophysiology, imaging findings, and clinical pearls of several intramural lesions including infarct, demyelinating lesions, traumatic injury, neoplasm, vascular malformation, and metabolic processes such as subacute combined degeneration.

Clinical evaluation of atlas and deep learning based automatic contouring for lung cancer.

BACKGROUND AND PURPOSE: Contouring of organs at risk (OARs) is an important but time consuming part of radiotherapy treatment planning. The aim of this study was to investigate whether using institutional created software-generated contouring will save time if used as a starting point for manual OAR contouring for lung cancer patients. MATERIAL AND METHODS: Twenty CT scans of stage I-III NSCLC patients were used to compare user adjusted contours after an atlas-based and deep learning contour, against manual delineation. The lungs, esophagus, spinal cord, heart and mediastinum were contoured for this study. The time to perform the manual tasks was recorded. RESULTS: With a median time of 20 min for manual contouring, the total median time saved was 7.8 min when using atlas-based contouring and 10 min for deep learning contouring. Both atlas based and deep learning adjustment times were significantly lower than manual contouring time for all OARs except for the left lung and esophagus of the atlas based contouring. CONCLUSIONS: User adjustment of software generated contours is a viable strategy to reduce contouring time of OARs for lung radiotherapy while conforming to local clinical standards. In addition, deep learning contouring shows promising results compared to existing solutions.

Growth of adult spinal cord in knifefish: Development and parametrization of a distributed model.

The study of indeterminate-growing organisms such as teleost fish presents a unique opportunity for improving our understanding of central nervous tissue growth during adulthood. Integrating the existing experimental data associated with this process into a theoretical framework through mathematical or computational modeling provides further research avenues through sensitivity analysis and optimization. While this type of approach has been used extensively in investigations of tumor growth, wound healing, and bone regeneration, the development of nervous tissue has been rarely studied within a modeling framework. To address this gap, the present work introduces a distributed model of spinal cord growth in the knifefish Apteronotus leptorhynchus, an established teleostean model of adult growth in the central nervous system. The proposed model incorporates two mechanisms, cell proliferation by active stem/progenitor cells and cell drift due to population pressure, both of which are subject to global constraints. A coupled reaction-diffusion equation approach was adopted to represent the densities of actively-proliferating and non-proliferating cells along the longitudinal axis of the spinal cord. Computer simulations using this model yielded biologically-feasible growth trajectories. Subsequent comparisons with whole-organism growth curves allowed the estimation of previously-unknown parameters, such as relative growth rates.