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Local anesthetic
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===Sensitivity of nerve fibers to local anesthetics=== For most patients, administration of local anesthetics causes the sensation of pain to be lost first, followed by temperature, touch, deep pressure, and finally motor function.<ref name=Catterall2023>{{cite book | vauthors = Catterall WA, Mackie K | date = 2023 | chapter = Local Anesthetics | veditors = Brunton LL, Knollmann BC | title = Goodman & Gilman's: The Pharmacological Basis of Therapeutics | edition = 14th | publisher = McGraw Hill | chapter-url = https://accessanesthesiology.mhmedical.com/content.aspx?bookid=3191§ionid=268045025 | isbn = 978-1-264-25807-9 }}</ref> The sensitivity of nerve fibers to blockade depends on a combination of diameter and myelination. Their different sensitivities to LA blockade is termed differential blockade. Myelinated fibers are more sensitive to blockade as they are interrupted by [[nodes of Ranvier]], thus interruption of only consecutive nodes of Ranvier will prevent action potential propagation. In turn, in unmyelinated nerves, an entire length needs to be blocked.<ref name=Piehl2015>{{cite book | vauthors = Piehl E, Bucklin BA | date = 2015 | chapter = Drugs commonly used in obstetric anesthesia. | veditors = Santos AC, Epstein JN, Chaudhuri K | title = Obstetric Anesthesia | publisher = McGraw Hill | chapter-url = https://accessanesthesiology.mhmedical.com/content.aspx?bookid=1364§ionid=82007590 | isbn = 978-0-07-178613-3 }}</ref> Regarding diameter, the generally accepted principle is that susceptibility to local anesthesia depends inversely on fiber diameter.<ref name=Gretchen2001>{{cite journal | vauthors = Henkel G | title = Susceptibility of Nerve Fibers to Local Anesthesia:"Size Principle" Challenged. | journal = The Journal of the American Society of Anesthesiologists | date = December 2001 | volume = 95 | issue = 6 | pages = 5A–6A | doi = 10.1097/00000542-200112000-00003 }}</ref> In general, autonomic fibers [[Group B nerve fiber|Type B fibers]], small unmyelinated [[Group C nerve fiber|type C]] (pain sensation), and small myelinated [[Group A nerve fiber|Aδ fibers]](pain and temperature sensations) are blocked before the larger myelinated Aγ, Aβ, and Aα fibers (mediating postural, touch, pressure, and motor information).<ref name=Catterall2023/>
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