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The Nervous System and Its Disorders
Published in Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss, Understanding Medical Terms, 2020
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss
The suffix round in "craniectomy" is also used in the term neurectomy, the surgical removal of a nerve tract. Cordotomy (also spelled chordotomy; literally "cutting the spinal cord") is the surgical procedure in which the spinothalamic tracts (nerve tracts from the spine to the thalamus), which conduct pain sensations to the consciousness, are severed in the cervical area; although seldom employed, the procedure can relieve severe pain in the pelvis and legs.
Distribution and Characteristics of Brain Dopamine
Published in Nira Ben-Jonathan, Dopamine, 2020
In addition to regulating important neurological functions such as locomotion, cognition and reward, the brain dopaminergic neurons are a critical component of the neuroendocrine functions of the brain. Three dopaminergic pathways, the IHDA, TIDA, and THDA, originate in the hypothalamus, supply DA to most hypothalamic nuclei and link the nervous system to the endocrine system via the pituitary gland. Within the pituitary gland, only the posterior pituitary (both neural and ILs) is directly connected to the hypothalamus through a nerve tract, whereas the anterior lobe is not innervated but, rather, receives hypothalamic information through the specialized hypophysial portal vasculature.
Hypothalamic Control Centers
Published in Nate F. Cardarelli, The Thymus in Health and Senescence, 2019
The SCN is the only hypothalamic area to receive direct retinal afferents.94 A monosynaptic retinohypothalamic nerve tract (RHT) terminates in the SCN.95,96 The RHT has been found in an extensive list of vertebrates, including the rat,70,97 guinea pig,97 rabbit,97 cat,97,98 monkey,95,97,98 platypus,99 opossum,98,100 hedgehog,98 tree shrew,98 galago,98 marmoset,98 ferret,101 mouse,102 and chimpanzee103 — as well as man.104 SCN cells respond to retinal input.70,82,105,106 Unilateral SCN lesions lead to a decrease in the mitotic index of the ipsilateral cornea.107 Bilateral lesions result in a lower mitotic index in both corneas.
Anatomical and functional identification of the external branch of the superior laryngeal nerve: classification based on morphology and electrophysiological monitoring
Published in Acta Chirurgica Belgica, 2022
The nerve branch was monitored during and after dissection as well as after full mobilization of the upper thyroid poles. IONM was performed using the nerve integrity monitor (NIM-Response 3.0 System; Medtronic Xomed, Jacksonville, FL, USA). The setup of the device included a stimulation intensity of 1-mA and an amplitude threshold of 100-µV. The nerve integrity monitor was connected to surface electrodes integrated with an endotracheal tube (NIM® EMG standard reinforced endotracheal tube; Medtronic Xomed). The tube was inserted between VCs under direct vision during intubation. The same monitor and the endotracheal tube system of IONM were used on all patients of these series. The dissection plane between the upper pole of the thyroid and the inferior constrictor muscle was carefully observed to visually identify the EBSLNs, followed by functional identification using IONM before the ligation of vascular branches. After full mobilization of the upper pole and at the end of surgery, the functional integrity of the EBSLNs was examined by IONM. The stimulator probe was directly applied to the EBSLN when visualized. The visualized branch was directly stimulated at approximately 3 cm before the edge of the CTM. If the nerve was not clearly visualized, the nerve tract on the constrictor muscle was indirectly stimulated at approximately 3 cm before the edge of the CTM for the creation and observation of the physiological response of the CTM.
Lactoferrin for Mental Health: Neuro-Redox Regulation and Neuroprotective Effects across the Blood-Brain Barrier with Special Reference to Neuro-COVID-19
Published in Journal of Dietary Supplements, 2021
Sreus A. G. Naidu, Taylor C. Wallace, Kelvin J. A. Davies, A. Satyanarayan Naidu
SARS-CoV-2 could infect the brain through neuroaxonal and hematogenous modes of transmission. The neuroaxonal transmission includes nasal (olfactory nerve track), ocular (optic nerve tract), and gastrointestinal (vagus nerve track) routes by trans-synaptic transfer via brain stem (Jakhmola et al. 2020). The hematogenous transmission is mainly through the pulmonary/circulatory routes via the BBB. Receptor recognition is the first step of viral infection, a key determinant of host cell/tissue tropism. Coronaviruses have evolved several complex host cell surface receptor recognition patterns. Angiotensin-converting enzyme 2 (ACE2) is a potential receptor for SARS-CoV-2 cellular docking and entry (Hoffmann et al. 2020), and ACE2 is widely expressed on various brain cells and cerebral regions. The resident CNS cells such as astrocytes and microglia also express ACE2; thereby, provide potential docking sites for viral attachment/entry into the brain (Jakhmola et al. 2020). A recent study reported that neuropilin-1 (NRP1), known to bind furin-cleaved substrates, could potentiate SARS-CoV-2 infection (Cantuti-Castelvetri et al. 2020). NRP1 is abundantly expressed in the respiratory and olfactory mucosa, with highest expression in endothelial and epithelial cells. Furthermore, SARS-CoV-2 also recognizes four other putative receptors on host cells; and binds to proteoglycans such as heparan sulfate via lectin-type interactions. Versatility in cell surface receptor interactions makes SARS-CoV-2 a multi-tropic viral pathogen (Naidu et al. 2020a).
Intraoperative Monitoring of External Branch of the Superior Laryngeal Nerve: Functional Identification, Motor Integrity, and its Role on Vocal Cord Function
Published in Journal of Investigative Surgery, 2018
Our rate of identification of EBSLNs shows that an appropriate upper pole dissection closer to the thyroidal tissue allows visual identification of the EBSLN in the majority of patients. Previous studies have reported that the EBSLN could be visually identified in 30%–93% of thyroidectomy cases [10, 12–16]. This suggests that an experienced thyroid surgeon can expose the EBSLN in a considerable number of cases. Despite anatomical integrity, it is not always possible to confirm adequate motor function of the nerve branch. The EBSLN innervates the CTM and provides contraction of this muscle to adjust VC tension. Monitoring is done to examine motor function of the EBSLN with the CTM twitch. Stimulation of the EBSLN tract on the inferior constrictor muscle created the CTM twitch revealing the functional integrity. Therefore, visual and functional identification rate of EBSLNs reached 97%. Previous studies have reported identification rates of EBSLN between 65% and 93% using IONM [10, 12–16]. A 100% electrophysiological identification rate of EBSLN has also been reported with the assistance of IONM [17]. Our visual identification rate of 66.9% and additional identification rate of 30.2% by IONM reveal the significant contribution of nerve monitoring to EBSLN identification. Authors have previously reported the rate of IONM contribution between 11.5% and 49.5% in addition to the rate of visual identification between 30% and 86% [10, 12–14, 18]. Stimulation of the nerve tract with 2 mA intensity helped to identify additional nerve branches. Therefore, we can suggest that some non-visualized nerve branches lying under the constrictor muscle fibers could be discovered by stimulation with higher intensity. Notably, if a neural mapping is performed (current amplitude increased from 1 mA to 2 mA), a relevant advantage achievable only via the IONM is that the EBSLN can be definitively identified even when the nerve is not visually detectable [7, 19]. Yu X et al. [20] reported that using a stimulation intensity of 3 mA can increase the EBSLN identification rate. Based on our results and previous reports, we can suggest that in case of non-visualized nerve branches, increasing the stimulation intensity allows identification of additional EBSLNs that run deeply under the inferior constrictor layer.