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The reticular activating system: a narrative review of discovery, evolving understanding, and relevance to current formulations of brain death
A series of landmark experiments conducted throughout the 20(th) century progressively localized the regions involved in consciousness to the reticular activating system (RAS) and its ascending projections. The first description of the RAS emerged in 1949 through seminal experiments performed by Mor...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Springer International Publishing
2023
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10203024/ https://www.ncbi.nlm.nih.gov/pubmed/37155119 http://dx.doi.org/10.1007/s12630-023-02421-6 |
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author | Taran, Shaurya Gros, Priti Gofton, Teneille Boyd, Gordon Briard, Joel Neves Chassé, Michaël Singh, Jeffrey M. |
author_facet | Taran, Shaurya Gros, Priti Gofton, Teneille Boyd, Gordon Briard, Joel Neves Chassé, Michaël Singh, Jeffrey M. |
author_sort | Taran, Shaurya |
collection | PubMed |
description | A series of landmark experiments conducted throughout the 20(th) century progressively localized the regions involved in consciousness to the reticular activating system (RAS) and its ascending projections. The first description of the RAS emerged in 1949 through seminal experiments performed by Moruzzi and Magoun in feline brainstems; additional experiments in the 1950s revealed connections between the RAS and the thalamus and neocortical structures. This knowledge has allowed for the explanation of disorders of consciousness with exquisite anatomic precision. The clinical relevance of the RAS is further apparent in modern definitions of brain death/death by neurologic criteria (BD/DNC), which require demonstration of the complete and permanent loss of capacity for consciousness as one of their core criteria. BD/DNC is currently understood across jurisdictions in terms of “whole brain” and “brainstem” formulations. Although their clinical examination between formulations is indistinguishable, policies for BD/DNC declaration may differ in the rare scenario of patients with isolated infratentorial brain injuries, in which ancillary testing is advised in the whole brain formulation but not the brainstem formulation. Canadian guidelines acknowledge that the distinction between whole brain and brainstem formulations is unclear with respect to clinical implications for patients with isolated infratentorial injuries. This has led to variability in Canadian clinicians’ use of ancillary testing when the mechanism of BD/DNC is suspected to be an isolated infratentorial injury. The present narrative review highlights these concepts and explores implications for determination of BD/DNC in Canada, with specific emphasis on the RAS and its relevance to both formulations. |
format | Online Article Text |
id | pubmed-10203024 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2023 |
publisher | Springer International Publishing |
record_format | MEDLINE/PubMed |
spelling | pubmed-102030242023-05-24 The reticular activating system: a narrative review of discovery, evolving understanding, and relevance to current formulations of brain death Taran, Shaurya Gros, Priti Gofton, Teneille Boyd, Gordon Briard, Joel Neves Chassé, Michaël Singh, Jeffrey M. Can J Anaesth Review Article/Brief Review A series of landmark experiments conducted throughout the 20(th) century progressively localized the regions involved in consciousness to the reticular activating system (RAS) and its ascending projections. The first description of the RAS emerged in 1949 through seminal experiments performed by Moruzzi and Magoun in feline brainstems; additional experiments in the 1950s revealed connections between the RAS and the thalamus and neocortical structures. This knowledge has allowed for the explanation of disorders of consciousness with exquisite anatomic precision. The clinical relevance of the RAS is further apparent in modern definitions of brain death/death by neurologic criteria (BD/DNC), which require demonstration of the complete and permanent loss of capacity for consciousness as one of their core criteria. BD/DNC is currently understood across jurisdictions in terms of “whole brain” and “brainstem” formulations. Although their clinical examination between formulations is indistinguishable, policies for BD/DNC declaration may differ in the rare scenario of patients with isolated infratentorial brain injuries, in which ancillary testing is advised in the whole brain formulation but not the brainstem formulation. Canadian guidelines acknowledge that the distinction between whole brain and brainstem formulations is unclear with respect to clinical implications for patients with isolated infratentorial injuries. This has led to variability in Canadian clinicians’ use of ancillary testing when the mechanism of BD/DNC is suspected to be an isolated infratentorial injury. The present narrative review highlights these concepts and explores implications for determination of BD/DNC in Canada, with specific emphasis on the RAS and its relevance to both formulations. Springer International Publishing 2023-05-08 2023 /pmc/articles/PMC10203024/ /pubmed/37155119 http://dx.doi.org/10.1007/s12630-023-02421-6 Text en © The Author(s) 2023 https://creativecommons.org/licenses/by-nc/4.0/Open AccessThis article is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, which permits any non-commercial use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc/4.0/ (https://creativecommons.org/licenses/by-nc/4.0/) . |
spellingShingle | Review Article/Brief Review Taran, Shaurya Gros, Priti Gofton, Teneille Boyd, Gordon Briard, Joel Neves Chassé, Michaël Singh, Jeffrey M. The reticular activating system: a narrative review of discovery, evolving understanding, and relevance to current formulations of brain death |
title | The reticular activating system: a narrative review of discovery, evolving understanding, and relevance to current formulations of brain death |
title_full | The reticular activating system: a narrative review of discovery, evolving understanding, and relevance to current formulations of brain death |
title_fullStr | The reticular activating system: a narrative review of discovery, evolving understanding, and relevance to current formulations of brain death |
title_full_unstemmed | The reticular activating system: a narrative review of discovery, evolving understanding, and relevance to current formulations of brain death |
title_short | The reticular activating system: a narrative review of discovery, evolving understanding, and relevance to current formulations of brain death |
title_sort | reticular activating system: a narrative review of discovery, evolving understanding, and relevance to current formulations of brain death |
topic | Review Article/Brief Review |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10203024/ https://www.ncbi.nlm.nih.gov/pubmed/37155119 http://dx.doi.org/10.1007/s12630-023-02421-6 |
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