Spinal and Epidural Anaesthesia
T.M. Craft, P.M. Upton in Key Topics In Anaesthesia, 2021
Spinal and epidural anaesthesia using local anaesthetics can produce profound analgesia, muscle relaxation, and a reduction in operative blood loss. Analgesia may also be provided by other agents injected into the cerebral spinal fluid (CSF) or epidural space. Neuroaxial anaesthesia is most effective when the site of is close to the affected dermatomes. Spinal or epidural anaesthesia may be considered for any operation to the lower limbs, perineum or lower abdomen. There are certain circumstances where it is especially indicated either with or without general anaesthesia. Spinal anaesthesia in particular is not a safe technique in those with cardiovascular disease such as fixed cardiac output states. Local anaesthetic agents block sodium channels, preventing neural transmission. Higher concentrations are required to block motor nerves which have the thickest myelin sheath. Full resuscitation facilities such as those found in a properly equipped anaesthetic room must be available prior to commencing neuraxial anaesthesia.
Diseases of the Nervous System
George Feuer, Felix A. de la Iglesia in Molecular Biochemistry of Human Disease, 2020
The nervous system shows many more specialized features compared to any other organ. This elaborate system contains complicated anatomical and functional structures and exhibits several unique metabolic processes. The signs of disorder in neurological functions also show variations according to the anatomic level of the nervous system involved. The incidence of Down’s disease is influenced by environmental and genetic factors which increase the occurence of nondisjunction and trisomy. The study of narcosis and excitation provides an initial tool when we evaluate various disease processes of the nervous system. Excitation in the central nervous system is associated with events leading to the firing of the neurons and generation of action potentials. Lesions of the nerves are associated with characteristic degenerative changes of injured nerve cells. These changes are primary or secondary, depending on the initial integrity of the axon and its interaction with the myelin sheath and the Schwann cell.
Muscle relaxants
Peter Nightingale in Anaesthetics for Junior Doctors and Allied Professionals, 2018
The term 'muscle relaxant' is slightly misleading and may conjure up the impression that these agents are in some way interfering with the intrinsic mechanism of muscular contraction. More in-depth analysis of the neuromuscular junction (NMJ) can be found in any good physiology book as it is useful to keep it in mind when considering how neuromuscular blocking drugs work. The NMJ is the junction between the terminal button of a motor neurone and the muscle fibre it innervates. The myelinated motor neuron looses its myelin sheath and forms a terminal button. Suxamethonium is the only depolarising neuromuscular blocking drug in routine use. Being able to monitor the degree of paralysis is vital when using neuromuscular blocking agents. There are several different methods used to measure neuromuscular blockade but by far the most common is visual observation of the response produced by electrical stimulation using a nerve stimulator.
Altered Brain Myelin Sheath Morphology after Rewarming in Situ
Published in Ultrastructural Pathology, 2010
E. S. Dietrichs, S. Lindal, T. Naesheim, T. Ingebrigtsen, T. Tveita
In this study cerebral ultrastructure was examined in an in vivo rat model, after rewarming from profound hypothermia (15–13°C). Animals held at 37°C served as controls. After rewarming, brains were examined by electron microscope. Micrographs were taken randomly, analyzed anonymously, and quantified by morphometry. Serum analysis of the stress marker S-100β was carried out in identical groups. The most striking findings in rewarmed animals, when compared to controls, were alterations of myelin sheaths (p
Neural mobilization promotes nerve regeneration by nerve growth factor and myelin protein zero increased after sciatic nerve injury
Published in Growth Factors, 2015
Joyce Teixeira da Silva, Fabio Martinez dos Santos, Aline Caroline Giardini, Daniel de Oliveira Martins, Mara Evany de Oliveira, Adriano Polican Ciena, Vanessa Pacciari Gutierrez, Ii-sei Watanabe, Luiz Roberto G. de Britto, Marucia Chacur
Neurotrophins are crucial in relation to axonal regrowth and remyelination following injury; and neural mobilization (NM) is a noninvasive therapy that clinically is effective in neuropathic pain treatment, but its mechanisms remains unclear. We examined the effects of NM on the regeneration of sciatic nerve after chronic constriction injury (CCI) in rats. The CCI was performed on adult male rats, submitted to 10 sessions of NM, starting 14 days after CCI. Then, the nerves were analyzed using transmission electron microscopy and western blot for neural growth factor (NGF) and myelin protein zero (MPZ). We observed an increase of NGF and MPZ after CCI and NM. Electron microscopy revealed that CCI-NM samples had high numbers of axons possessing myelin sheaths of normal thickness and less inter-axonal fibrosis than the CCI. These data suggest that NM is effective in facilitating nerve regeneration and NGF and MPZ are involved in this effect.
Histological and ultrastructural study of AflatoxinB1 induced neurotoxicity in Sciatic nerve of adult male Albino rats
Published in Ultrastructural Pathology, 2020
Aflatoxins are mycotoxins produced by Aspergillus spp. which is a common contaminant of food items such as corn, spices, rice, nuts, and flour. Aflatoxin contamination of foods is a worldwide problem. Chronic aflatoxin exposure is found to be associated with Sciatic nerve damage. In vivo study was carried out to evaluate the toxic effect of aflatoxin B1 (AFB1) on the Sciatic nerve. Twenty-one adult male rats were included and divided equally into 3 groups (7 rats each): Group I (control group), group II (olive oil group) and group III: (AflatoxinB1 group). The rats received AFB1 (250 μg/kg B.W./day) orally by gastric tube 5 days/week for 4 weeks. Sciatic nerve specimens were prepared, and semi-thin sections were stained with Toluidine blue, examined by light microscope and photographed. Ultrathin sections (50–80 nm) from selected areas of the trimmed blocks were made, examined and photographed by transmission electron microscopy (JEOL-JSM-1011) in King Saud University Electron Microscopy Unit. The findings indicate that the administration of AFB1 to rats’ results in degeneration in the sciatic nerve in the form of Wallerian degeneration in the myelin sheath. Macrophages appear to engulf the degenerated myelin and neutrophils.
Related Knowledge Centers
- Axon
- Nerve Tissue
- Oligodendroglia
- Unmyelinated Nerve Fibers
- Central Nervous Systems
- Schwann Cells
- Cell Membrane Structures