词条 | Reflex syncope |
释义 |
| name = Reflex syncope | synonyms = Neurally mediated syncope, neurocardiogenic syncope[1][2] | image = Gray793.png | caption = Vagus nerve | field = Neurology, cardiovascular | symptoms = Loss of consciousness before which there may be sweating, decreased ability to see, ringing in the ears[1][2] | complications = Injury[1] | onset = | duration = Brief[1] | types = Vasovagal, situational, carotid sinus syncope[1] | causes = | risks = | diagnosis = Based on symptoms after ruling out other possible causes[8] | differential = Arrhythmia, orthostatic hypotension, seizure, hypoglycemia[1] | prevention = | treatment = Avoiding triggers, drinking sufficient fluids, exercise, cardiac pacemaker[2] | medication = Midodrine, fludrocortisone[11] | prognosis = | frequency = > 1 per 1,000 people per year[1] | deaths = }}Reflex syncope is a brief loss of consciousness due to a neurologically induced drop in blood pressure.[1] Before the person passes out there may be sweating, a decreased ability to see, or ringing in the ears.[2] Occasionally the person may twitch when unconscious.[2] Complications may include injury from a fall.[2] Reflex syncope is divided into three types: vasovagal, situational, and carotid sinus.[1] Vasovagal syncope is typically triggered by seeing blood, pain, emotional stress, or prolonged standing.[3] Situational syncope is often triggered by urination, swallowing, or coughing.[1] Carotid sinus syncope is due to pressure on the carotid sinus in the neck.[1] The underlying mechanism involves the nervous system slowing the heart rate and dilating blood vessels resulting in low blood pressure and therefore not enough blood flow to the brain.[1] Diagnosis is based on symptoms after ruling out other possible causes.[4] Recovery happens without specific treatment.[1] Prevention involves avoiding the triggers.[1] Drinking sufficient fluids, salt, and exercise may also be useful.[1][5] If this is not sufficient for vasovagal syncope, medications like midodrine or fludrocortisone may be tried.[5] Occasionally a cardiac pacemaker may be used.[1] Reflex syncope affects at least 1 per 1,000 people a year.[2] It is the most common type of syncope, making up more than 50% of all cases.[1] Signs and symptomsEpisodes of vasovagal syncope are typically recurrent and usually occur when the predisposed person is exposed to a specific trigger. Before losing consciousness, the individual frequently experiences early signs or symptoms such as lightheadedness, nausea, the feeling of being extremely hot or cold (accompanied by sweating), ringing in the ears, an uncomfortable feeling in the heart, fuzzy thoughts, confusion, a slight inability to speak or form words (sometimes combined with mild stuttering), weakness and visual disturbances such as lights seeming too bright, fuzzy or tunnel vision, black cloud-like spots in vision, and a feeling of nervousness can occur as well. The symptoms may become more intense over several seconds to several minutes before the loss of consciousness (if it is lost). Onset usually occurs when a person is sitting up or standing. When people lose consciousness, they fall down (unless prevented from doing so) and, when in this position, effective blood flow to the brain is immediately restored, allowing the person to regain consciousness. If the person does not fall into a fully flat, supine position, and the head remains elevated above the trunk, a state similar to a seizure may result from the blood's inability to return quickly to the brain, and the neurons in the body will fire off and generally cause muscles to twitch very slightly but mostly remain very tense. The autonomic nervous system's physiological state (see below) leading to loss of consciousness may persist for several minutes, so
CauseReflex syncope occurs in response to a trigger due to dysfunction of the heart rate and blood pressure regulating mechanism. When heart rate slows or blood pressure drops, the resulting lack of blood to the brain causes fainting.[6] Vasovagal syncopeTypical triggers include:
Situational syncope
Carotid sinus syncopePressing upon a certain spot in the neck.[3] This may happen when wearing a tight collar, shaving, or turning the head.[3] PathophysiologyRegardless of the trigger, the mechanism of syncope is similar in the various vasovagal syncope syndromes. The nucleus tractus solitarii of the brainstem is activated directly or indirectly by the triggering stimulus, resulting in simultaneous enhancement of parasympathetic nervous system (vagal) tone and withdrawal of sympathetic nervous system tone. This results in a spectrum of hemodynamic responses:
One account for these physiological responses is the Bezold-Jarisch reflex. Vasovagal syncope may be an evolution response, specifically the fight-or-flight response.[8][9] DiagnosisIn addition to the mechanism described above, a number of other medical conditions may cause syncope. Making the correct diagnosis for loss of consciousness is difficult. The core of the diagnosis of vasovagal syncope rests upon a clear description of a typical pattern of triggers, symptoms, and time course. It is pertinent to differentiate lightheadedness, seizures, vertigo, and low blood sugar as other causes. In people with recurrent vasovagal syncope, diagnostic accuracy can often be improved with one of the following diagnostic tests:
TreatmentTreatment for reflex syncope focuses on avoidance of triggers, restoring blood flow to the brain during an impending episode, and measures that interrupt or prevent the pathophysiologic mechanism described above. Lifestyle changes
Medications
Types of long-term therapy for vasovagal syncope include[10]
Prognosis{{Expand section|date=January 2009}}Brief periods of unconsciousness usually cause no lasting harm to health. Reflex syncope can occur in otherwise healthy individuals, and has many possible causes, often trivial ones such as prolonged standing.{{Citation needed|date=April 2017}} The main danger of vasovagal syncope (or dizzy spells from vertigo) is the risk of injury by falling while unconscious. Medication therapy could possibly prevent future vasovagal responses; however, for some individuals medication is ineffective and they will continue to have fainting episodes.[21] See also
References1. ^1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 {{cite journal|last1=Adkisson|first1=WO|last2=Benditt|first2=DG|title=Pathophysiology of reflex syncope: A review.|journal=Journal of Cardiovascular Electrophysiology|date=September 2017|volume=28|issue=9|pages=1088–1097|doi=10.1111/jce.13266|pmid=28776824}} 2. ^1 2 3 4 5 6 7 8 9 10 {{cite journal|last1=Aydin|first1=MA|last2=Salukhe|first2=TV|last3=Wilke|first3=I|last4=Willems|first4=S|title=Management and therapy of vasovagal syncope: A review.|journal=World Journal of Cardiology|date=26 October 2010|volume=2|issue=10|pages=308–15|doi=10.4330/wjc.v2.i10.308|pmid=21160608|pmc=2998831}} 3. ^1 2 3 4 5 6 {{cite web|title=Syncope Information Page|url=https://www.ninds.nih.gov/Disorders/All-Disorders/Syncope-Information-Page|website=National Institute of Neurological Disorders and Stroke|accessdate=9 November 2017}} 4. ^1 {{cite book|last1=Brignole|first1=Michele|last2=Benditt|first2=David G.|title=Syncope: An Evidence-Based Approach|date=2011|publisher=Springer Science & Business Media|isbn=9780857292018|page=158|url=https://books.google.ca/books?id=i-p7twz4qyIC&pg=PA158|language=en}} 5. ^1 2 {{cite journal|last1=Shen|first1=WK|last2=Sheldon|first2=RS|last3=Benditt|first3=DG|last4=Cohen|first4=MI|last5=Forman|first5=DE|last6=Goldberger|first6=ZD|last7=Grubb|first7=BP|last8=Hamdan|first8=MH|last9=Krahn|first9=AD|last10=Link|first10=MS|last11=Olshansky|first11=B|last12=Raj|first12=SR|last13=Sandhu|first13=RK|last14=Sorajja|first14=D|last15=Sun|first15=BC|last16=Yancy|first16=CW|title=2017 ACC/AHA/HRS Guideline for the Evaluation and Management of Patients With Syncope: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society.|journal=Circulation|date=1 August 2017|volume=136|issue=5|pages=e25–e59|doi=10.1161/CIR.0000000000000498|pmid=28280232}} 6. ^{{cite web |url=http://www.mayoclinic.org/diseases-conditions/vasovagal-syncope/symptoms-causes/dxc-20184778 |title=Vasovagal syncope: Causes |publisher=MayoClinic.com |date=7 August 2010 |deadurl=no |access-date=10 August 2016}} 7. ^{{cite journal |vauthors=Rossi S, Hallett M, Rossini PM, Pascual-Leone A |title=Safety, ethical considerations, and application guidelines for the use of transcranial magnetic stimulation in clinical practice and research |journal=Clinical Neurophysiology |volume=120 |issue=12 |pages=2008–2039 |year=2009 |pmid=19833552 |pmc=3260536 |doi=10.1016/j.clinph.2009.08.016|hdl=11572/145680 }} 8. ^{{cite journal |title=Vasovagal syncope in humans and protective reactions in animals|date=2015|vauthors=Blanc JJ, Alboni P, Benditt DG|pmid=25662986|doi=10.1093/europace/euu367|volume=17|issue=3|journal=Europace|pages=345–9}} 9. ^{{cite journal |title=Vasovagal Syncope As A Manifestation Of An Evolutionary Selected Trait|journal=Journal of Atrial Fibrillation|date=2014|vauthors=Alboni P, Alboni M|pmc=5135249|pmid=27957092|doi=10.4022/jafib.1035|volume=7|issue=2|page=1035|doi-broken-date=2019-02-21}} 10. ^1 {{cite journal |vauthors=Fenton AM, Hammill SC, Rea RF, Low PA, Shen WK |title=Vasovagal syncope |journal=Ann. Intern. Med. |volume=133 |issue=9 |pages=714–25 |year=2000 |doi=10.7326/0003-4819-133-9-200011070-00014 |pmid=11074905 }} 11. ^1 {{Cite book |author1=Durand, VM |author2=DH Barlow |year=2006 |title=Essentials of Abnormal Psychology 4th Edition |page=150 |url=https://books.google.com/?id=OCaeCAAAQBAJ&pg=PT6&dq=Durand,+VM,+and+DH+Barlow.+2006.+Essentials+of+Abnormal+Psychology+4th+Edition#v=onepage&q&f=false |deadurl=no |accessdate=12 August 2016|isbn=978-1111836986 }} 12. ^{{cite book |last1=Hersen |first1=Michel |title=Encyclopedia of Behavior Modification and Cognitive Behavior Therapy |date=2005 |publisher=SAGE |isbn=9780761927471 |page=30 |url=https://books.google.ca/books?id=LF05DQAAQBAJ&pg=PT50 |language=en}} 13. ^1 {{cite book |last1=Felgoise |first1=Stephanie |last2=Nezu |first2=Arthur M. |last3=Nezu |first3=Christine M. |last4=Reinecke |first4=Mark A. |title=Encyclopedia of Cognitive Behavior Therapy |date=2006 |publisher=Springer Science & Business Media |isbn=9780306485817 |page=291 |url=https://books.google.ca/books?id=bQ1KAAAAQBAJ&pg=PA291 |language=en}} 14. ^{{cite journal |vauthors=France CR, France JL, Patterson SM |title=Blood pressure and cerebral oxygenation responses to skeletal muscle tension: a comparison of two physical maneuvers to prevent vasovagal reactions |journal=Clin Physiol Funct Imaging |volume=26 |issue=1 |pages=21–5 |date=January 2006 |pmid=16398666 |doi = 10.1111/j.1475-097X.2005.00642.x | url = }} 15. ^{{cite journal |vauthors=Sheldon R, Connolly S, Rose S, Klingenheben T, Krahn A, Morillo C, Talajic M, Ku T, Fouad-Tarazi F, Ritchie D, Koshman ML | title = Prevention of Syncope (POST): a randomized, placebo-controlled study of metoprolol in the prevention of vasovagal syncope | journal = Circulation | volume = 113 | issue = 9 | pages = 1164–70 | date = March 2006 | pmid = 16505178 | doi = 10.1161/CIRCULATIONAHA.105.535161 }} 16. ^{{cite journal |vauthors=Madrid AH, Ortega J, Rebollo JG, Manzano JG, Segovia JG, Sánchez A, Peña G, Moro C | title = Lack of efficacy of atenolol for the prevention of neurally mediated syncope in a highly symptomatic population: a prospective, double-blind, randomized and placebo-controlled study | journal = J. Am. Coll. Cardiol. | volume = 37 | issue = 2 | pages = 554–9 | date = February 2001 | pmid = 11216978 | doi = 10.1016/S0735-1097(00)01155-4 }} 17. ^{{cite journal|title= The use of methylphenidate in the treatment of refractory neurocardiogenic syncope|date=2012-05-24 |pmid=8734752 | volume=19|issue=5 |journal=Pacing Clin Electrophysiol|pages=836–40|vauthors=Grubb BP, Kosinski D, Mouhaffel A, Pothoulakis A |doi=10.1111/j.1540-8159.1996.tb03367.x }} 18. ^{{cite journal|last1=Ali Aydin|first1=Muhammet|last2=Salukhe|first2=Tushar|last3=Wilkie|first3=Iris|last4=Willems|first4=Stephan|title=Management and therapy of vasovagal syncope: A review|journal=World J Cardiol|pmc=2998831|pmid=21160608|doi=10.4330/wjc.v2.i10.308|volume=2|issue=10|year=2010|pages=308–15}} 19. ^{{Cite journal|url=http://web.squ.edu.om/med-Lib/MED_CD/E_CDs/Nursing%20Drug%20Guide/mg/epinephrine.htm |title=epinephrine (adrenaline) |author=Amy M. Karch |journal=2006 Lippincott's Nursing Drug Guide |deadurl=no |accessdate=12 August 2016}} 20. ^{{cite web |title=Vasovagal Syncope: What is it? |url=http://www.vasovagal-syncope.com/ |deadurl=yes |archiveurl=https://web.archive.org/web/20140103161954/http://vasovagal-syncope.com/ |archivedate=3 January 2014 |accessdate=11 August 2016}} 21. ^{{cite web |url=http://www.mdguidelines.com/vasovagal-syncope/prognosis |title=Vasovagal Syncope Prognosis |publisher=MDGuidelines |deadurl=no |accessdate=11 August 2016}} External links{{Medical resources| DiseasesDB = 13777 | ICD10 = {{ICD10|R|55||r|50}} | ICD9 = {{ICD9|78Ø.2}} | ICDO = | OMIM =609289 | MedlinePlus = | eMedicineSubj = | eMedicineTopic = | MeshID = D019462 }}{{Cognition, perception, emotional state and behaviour symptoms and signs}}{{Autonomic diseases}}{{DEFAULTSORT:Vasovagal Episode}}Synkope (Medizin)#Neural vermittelte Synkope 4 : Cardiology|Vagus nerve|Symptoms and signs: Cognition, perception, emotional state and behaviour|RTT |
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