carotid sinus#Carotid sinus reflex death

The carotid sinus is the reflex area of the carotid artery, consisting of baroreceptors which monitor blood pressure.

{{More citations needed|section|date=November 2020}}

The carotid sinus contains numerous baroreceptors which function as a "sampling area" for many homeostatic mechanisms for maintaining blood pressure. The carotid sinus baroreceptors are innervated by the carotid sinus nerve, which is a branch of the glossopharyngeal nerve (CN IX).{{cite book | vauthors = Câmara R, Griessenauer CJ | chapter = Chapter 27 - Anatomy of the Vagus Nerve|date= January 2015 | title = Nerves and Nerve Injuries|pages=385–397| veditors = Tubbs RS, Rizk E, Shoja MM, Loukas M |place=San Diego|publisher=Academic Press|language=en|doi=10.1016/b978-0-12-410390-0.00028-7|isbn=978-0-12-410390-0 }}{{cite book | vauthors = Hermanowicz N |chapter=Chapter 13 - Cranial Nerves IX (Glossopharyngeal) and X (Vagus)|date= January 2007 | title = Textbook of Clinical Neurology | edition = Third |pages=217–229| veditors = Goetz CG |place=Philadelphia|publisher=W.B. Saunders|language=en|doi=10.1016/b978-141603618-0.10013-x|isbn=978-1-4160-3618-0 }} The neurons which innervate the carotid sinus centrally project to the solitary nucleus in the medulla of the brainstem. The solitary nucleus indirectly modulates the activity of sympathetic and parasympathetic neurons in the medulla and pons through the hypothalamus. These neurons then regulate the autonomic control of the heart and blood vessels. The aortic arch baroreceptors are innervated by the aortic nerve (nerve of Cyon, Ludwig nerve), which combines with CN X (vagus nerve) and travels to the NTS.

It is a sensitive site of the body because stimulation can drive large-scale reflex effects throughout the body. This can be used therapeutically in treatment of resistant hypertension{{cite journal | vauthors = Scheffers IJ, Kroon AA, Schmidli J, Jordan J, Tordoir JJ, Mohaupt MG, Luft FC, Haller H, Menne J, Engeli S, Ceral J, Eckert S, Erglis A, Narkiewicz K, Philipp T, de Leeuw PW | title = Novel baroreflex activation therapy in resistant hypertension: results of a European multi-center feasibility study | journal = Journal of the American College of Cardiology | volume = 56 | issue = 15 | pages = 1254–1258 | date = October 2010 | pmid = 20883933 | doi = 10.1016/j.jacc.2010.03.089 | doi-access = free }} by baroreflex activation. Physical assault at this point, producing massive baroreflex activation can cause dramatic falls in blood pressure and cerebral ischemia. This is the mechanism of baroreflex activation therapy.

{{anchor|Disease of the carotid sinus}}

The carotid sinus often has atherosclerotic plaques because of disturbed hemodynamics (low wall shear stress, flow reversal/recirculation).{{cite journal | vauthors = Glagov S, Zarins C, Giddens DP, Ku DN | title = Hemodynamics and atherosclerosis. Insights and perspectives gained from studies of human arteries | journal = Archives of Pathology & Laboratory Medicine | volume = 112 | issue = 10 | pages = 1018–1031 | date = October 1988 | pmid = 3052352 }} Since these plaques, if large and unstable, predispose to ischemic strokes and transient ischemic attacks, carotid endarterectomies are frequently done for prophylaxis.

The carotid sinus baroreceptor can be oversensitive to manual stimulation from the pressure applied at the carotid sinus at the carotid bifurcation. It is a condition known as 'carotid sinus hypersensitivity' (CSH), 'carotid sinus syndrome' or 'carotid sinus syncope', in which manual stimulation causes large changes in heart rate and blood pressure, which can result in bradycardia, vasodilation, and hypotension. This classically presents as a patient who has "fainted" (actually a presyncope) on several occasions while shaving, or in some other way coming into contact with their carotid sinus. Denervation is performed as treatment for this.{{cite book | vauthors = Kharsa A, Wadhwa R | chapter = Carotid Sinus Hypersensitivity |date=2024 | title = StatPearls | chapter-url = http://www.ncbi.nlm.nih.gov/books/NBK559059/ |access-date=2024-03-23 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=32644485}}{{Cite journal | vauthors = Wijetunga MN |date=2021-10-16 | veditors = Talavera F, Compton SJ |title=Carotid Sinus Hypersensitivity: Background, Pathophysiology, Epidemiology |url=https://emedicine.medscape.com/article/153312-overview?form=fpf | journal = Medscape }}

Usually older patients with syncope and unexplained falls often have coexisting conditions such as carotid sinus hypersensitivity, orthostatic hypotension, and vasovagal syncope.{{cite journal | vauthors = Tan MP, Chadwick TJ, Kerr SR, Parry SW | title = Symptomatic presentation of carotid sinus hypersensitivity is associated with impaired cerebral autoregulation | journal = Journal of the American Heart Association | volume = 3 | issue = 3 | pages = e000514 | date = June 2014 | pmid = 24947997 | pmc = 4309040 | doi = 10.1161/JAHA.113.000514 }}

Carotid sinus syndrome (CSS) is a temporary loss of consciousness that sometimes accompanies convulsive seizures because of the intensity of the carotid sinus reflex when pressure builds in one or both carotid sinuses.{{cite journal | vauthors = Wallbach M, Koziolek MJ | title = Baroreceptors in the carotid and hypertension-systematic review and meta-analysis of the effects of baroreflex activation therapy on blood pressure | journal = Nephrology, Dialysis, Transplantation | volume = 33 | issue = 9 | pages = 1485–1493 | date = September 2018 | pmid = 29136223 | doi = 10.1093/ndt/gfx279 | doi-access = free }}

Stimulation of baroreceptors at the carotid sinus can be used to treat resistant hypertension via activation of the baroreflex. A pacemaker-like device can be implanted to electrically stimulate the receptors chronically, which is found to lower blood pressure by 15–25 mmHg.

{{see also|vagal maneuver|Czermak–Hering test}}

Massage of the carotid sinus, carotid sinus massage is used to diagnose carotid sinus syncope and is sometimes useful for differentiating supraventricular tachycardia (SVT) from ventricular tachycardia. Like the valsalva maneuver, it is a treatment for acute SVT.{{cite journal | vauthors = Lim SH, Anantharaman V, Teo WS, Goh PP, Tan AT | title = Comparison of treatment of supraventricular tachycardia by Valsalva maneuver and carotid sinus massage | journal = Annals of Emergency Medicine | volume = 31 | issue = 1 | pages = 30–35 | date = January 1998 | pmid = 9437338 | doi = 10.1016/S0196-0644(98)70277-X }} It is less effective than pharmaceutical management of SVT with verapamil or adenosine,{{cite journal | vauthors = Ballo P, Bernabò D, Faraguti SA | title = Heart rate is a predictor of success in the treatment of adults with symptomatic paroxysmal supraventricular tachycardia | journal = European Heart Journal | volume = 25 | issue = 15 | pages = 1310–1317 | date = August 2004 | pmid = 15288158 | doi = 10.1016/j.ehj.2004.05.011 | doi-access = free }} but it is still the preferred first line of treatment in a hemodynamically stable patient.{{cite book | veditors = Field JM, Ruple J | publisher = American Heart Association. | chapter = Managing Stable Tachycaradia: the ACLS Tachycardia Algorithm | page = 98 | title = Advanced Cardiac Life Support Provider Manual | date = 2007 | isbn = 978-0-87493-496-0 }}

Carotid sinus reflex death is a potential etiology of sudden death in which manual stimulation of the carotid sinus allegedly causes strong glossopharyngeal nerve (Vagus nerve is for aortic arch baroreceptors) impulses leading to terminal cardiac arrest. Carotid sinus reflex death has been pointed out as a possible cause of death in cases of strangulation, hanging and autoerotic strangulation, but such deductions remain controversial. Medical literature examining the use of carotid sinus massage involving brief gentle pressure of the carotid sinus in therapeutic settings as a diagnostic and therapeutic examination tool have reported few potentially fatal complications.{{cite journal | vauthors = Greenwood RJ, Dupler DA | title = Death following carotid sinus pressure | journal = JAMA | volume = 181 | issue = 7 | pages = 605–609 | date = August 1962 | pmid = 13901589 | doi = 10.1001/jama.1962.03050330035007 }}{{cite journal | vauthors = Deepak SM, Jenkins NP, Davidson NC, Bennett DH, Mushahwar SS | title = Ventricular fibrillation induced by carotid sinus massage without preceding bradycardia | journal = Europace | volume = 7 | issue = 6 | pages = 638–640 | date = November 2005 | pmid = 16216770 | doi = 10.1016/j.eupc.2005.06.006 | doi-access = free }}{{cite book | vauthors = Vilke GM | chapter = Neck Holds | chapter-url = https://books.google.com/books?id=BFl6GGZsqp4C&dq=carotid+sinus+reflex+chokehold&pg=PA28 | veditors = Ross DL, Chan T | title = Sudden Deaths in Custody | publisher = Springer Science & Business Media | date = 2007 | isbn = 978-1-59745-015-7 }}{{cite web | vauthors = Passig K | url = http://www.datenschlag.org/howto/atem/english/csr.html | title = Carotid sinus reflex death - a theory and its history | archive-url = https://web.archive.org/web/20120504044744/http://datenschlag.org/howto/atem/english/csr.html | work = Datenschlag | archive-date = 4 May 2012 | access-date = 28 February 2006 }}{{cite journal | vauthors = Mankikar GD, Clark AN | title = Cardiac effects of carotid sinus massage in old age | journal = Age and Ageing | volume = 4 | issue = 2 | pages = 86–94 | date = May 1975 | pmid = 1146669 | doi = 10.1093/ageing/4.2.86 }} A carotid massage can also possibly dislodge a thrombus, or some plaque. This could lead to any number of life-threatening effects, including stroke.

Stimulation of the carotid sinus via a slap or a strike, to induce (usually temporary, but sometimes lethal) loss of consciousness is a self-defense technique, and is often taught in martial arts such as karate.{{cite web | vauthors = Sensei B | date = 8 November 2013 |url= http://www.fullpotentialma.com/self-defense-slap/|title=Carotid Sinus strike/slap as an effective self defense technique |publisher=Full Potential Martial Arts|access-date=30 May 2015}}

• Baroreflex
• Carotid body

{{Reflist}}

File:Slide12hhh.JPG|Carotid sinus

• {{NormanAnatomy|lesson5}} ({{NormanAnatomyFig|livingneck}})

{{Arteries of chest}}

{{Arteries of head and neck}}

{{Authority control}}

{{DEFAULTSORT:Carotid Sinus}}

Category:Arteries of the head and neck