Editing Tetanus toxin (section)

==Clinical significance==
The clinical manifestations of tetanus are caused when tetanus toxin blocks inhibitory impulses, by interfering with the release of [[neurotransmitter]]s, including [[glycine]] and [[gamma-aminobutyric acid]]. These inhibitory neurotransmitters inhibit the [[alpha motor neuron]]s. With diminished inhibition, the resting firing rate of the alpha motor neuron increases, producing rigidity, unopposed muscle contraction and spasm. Characteristic features are [[risus sardonicus]] (a rigid smile), [[trismus]] (commonly known as "lock-jaw"), and [[opisthotonus]] (rigid, arched back). [[Seizures]] may occur, and the [[autonomic nervous system]] may also be affected. Tetanospasmin appears to prevent the release of neurotransmitters by selectively cleaving a component of synaptic vesicles called [[synaptobrevin]] II.<ref name=Todar>{{cite book| vauthors = Todar K |date=2005 |chapter-url=http://textbookofbacteriology.net/clostridia_3.html |access-date=24 June 2018 |chapter=Pathogenic Clostridia, including Botulism and Tetanus |title=Todar's Online Textbook of Bacteriology}}</ref> Loss of inhibition also affects preganglionic sympathetic neurons in the lateral [[gray matter]] of the spinal cord and produces sympathetic hyperactivity and high circulating [[catecholamine]] levels. [[Hypertension]] and [[tachycardia]] alternating with [[hypotension]] and [[bradycardia]] may develop.<ref name="isbn0-07-146633-9">{{cite book | vauthors = Loscalzo J, Fauci AS, Braunwald E, Kasper DL, Hauser SL, Longo DL |title=Harrison's principles of internal medicine |publisher=McGraw-Hill Medical |year=2008 |isbn=978-0-07-146633-2 }}</ref><ref name="urlTetanus in Emergency Medicine">{{cite web | vauthors = Yabes Jr JM, McLaughlin R | veditors = Brusch JL |url=http://emedicine.medscape.com/article/786414-overview |title=Tetanus in Emergency Medicine |work=Emedicine |access-date=2011-09-01}}</ref>

Tetanic spasms can occur in a distinctive form called ''[[opisthotonos]]'' and be sufficiently severe to fracture long bones. The shorter nerves are the first to be inhibited, which leads to the characteristic early symptoms in the face and jaw, ''[[risus sardonicus]]'' and [[Tetanus|lockjaw]].