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Syncope is the formal medical term for fainting, describing a temporary loss of consciousness due to a sudden decline in blood flow to the brain.  ​

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Pre-Syncope is when someone comes close to fainting, but is able to avoid an actual loss of consciousness, usually by lying down.

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Syncope is common, and can be caused by numerous things. It accounts for approximately 3% of ER visits and 6% of hospital admissions. Some forms of syncope are harmless, while other forms can indicate serious health problems. After a fainting episode, an individual may be temporarily unconscious, but will revive and return to normal. Syncope can occur in otherwise healthy people and affects all age groups, but occurs more often in the elderly.
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                    Types of Syncope​​​​​​​​​​​

 

 

Neurally Mediated Syncope (NMS): previously called Neurocardiogenic Syncope(NCS) and Neurally Mediated Hypotension (NMH), is usually characterized as a chronic condition caused by peripheral vasodilation (blood pooling in the extremities), a decrease in blood pressure, and a slow or lowered heart rate upon standing.  The low blood pressure leads to fainting if it is severe enough, or to lightheadedness (pre-syncope) if less severe or if the patient is lying down.This is considered a type of Dysautonomia, and can seriously impair the quality of life of a person.​​

 

Reflex Syncope: sometimes known as "the common faint" because it is common. It can occur for a variety of reasons, usually termed "trigger events." Estimates of isolated (one time) fainting episodes range from 15-25% in young people.  Approximately 25% of elderly people faint, which may relate to use of medications or to physiological changes. Over 50% of people will faint at some point in their life.  Reflex Syncope includes the following:

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• Vasovagal Syncope: trigger events can include: emotional stress, trauma, the sight of blood or needles, prolonged standing, and sudden fear. These are usually considered "harmless," as the person immediately regains consciousness upon lying down and has no other health issues related to the faint.
• Carotid Sinus Syncope: occurs because of constriction of the carotid artery in the neck and can occur after turning the head, while shaving, or when wearing a tight collar.​
• Situational Syncope: occurs during or immediately after urination, defecation, coughing, laughing, or as a result of gastrointestinal stimulation.​
• Cardiac Syncope/Heart-Rhythm Disorders: may cause syncope if the heart rate is too slow or too fast, but variable. Occasionally, heart-rhythm problems cause syncope in otherwise healthy people, but individuals with underlying heart disease (such as a previous heart attack or heart valve disease) are at greater risk.Cardiac syncope is often quite serious. The first step in evaluating syncope is to evaluate the patient for possible cardiac syncope. Causes of cardiac syncope include: Long QT syndrome, Arrhythmogenic right ventricular dysplasia (ARVD), Cardiomyopathies, Left Ventricular Outflow Obstruction, Myocardial Infarction, Primary Pulmonary Hypertension, & Heart Arrythmias.​

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                          Diagnosis & Treatment​​​​​​​​​​​​

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The diagnosis of Neurally Mediated Syncope often focuses on ruling out potentially serious causes of syncope, particularly heart-related problems.  Diagnostic criteria include a drop in both blood pressure and heart rate upon standing; either causing syncope or pre-syncopal symptoms.​

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Tests may include the autonomic tests found here, along with various cardiac tests determined after taking a detailed medical history.

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Treatment often includes:
- Avoiding syncope triggers
- Increasing salt and fluid intake to expand blood volume and raise blood pressure
- Compression stockings and garments
- Mild to moderate aerobic conditioning, as tolerated (under supervision of a physician or specialized Physical Therapist)
- Medications based on individual symptoms

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                           Outlook for Patients:​​​​​​​​​​​​

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​The prognosis for syncope patients depends on which type of syncope they have. Patients and caregivers must be educated on what to do during a syncopal attack and how to minimize the chance of injury during a syncopal episode. Most patients will improve with proper education on the avoidance of triggers, working to expand fluid volume/hydration, and in some cases medication.

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For those with NMS, controlling symptoms daily or as they come and go can be challenging.  Working with an experienced provider to come up with an individual plan to maintain blood pressure, expand blood volume in those who are hypovolemic, and prevent falls is very important.  Some patients that faint multiple times a day opt to wear a helmet for protection, as falling on hard surfaces can be very dangerous and cause serious injury.

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Sources
1. NIH Autonomic Disorders Consortium

2. Neurally-mediated syncope. Brignole M, Ital Heart J. 2005 Mar;6(3):249-55.

3. Dysautonomia and neurocardiogenic syncope. McLeod KA. Curr Opin Cardiol. 2001 Mar;16(2):92-6.

4. Physiological phenomenology of neurally-mediated syncope with management implications. Schroeder C et al, PLoS One. 2011;6(10):e26489. Epub 2011 Oct 25.

5. Familial aggregation of fainting in a case-control study of neurally mediated hypotension patients who present with unexplained chronic fatigue. Lucas KE et al., Europace. 2006 Oct;8(10):846-51. Epub 2006 Aug 18.

6. Vanderbilt Autonomic Dysfunction Center

7. Neurally Mediated Syncope.? Zaqqa M et al., Tex Heart Inst J. 2000; 27(3): 268?272.

8. Orthostatic Intolerance. Julian M Stewart, MD, PhD? Associate Chairman of Pediatrics, Director, Center for Hypotension, Westchester Medical Center; Professor of Pediatrics and Physiology, New York Medical College, Medline Article.

9. Consensus statement on the definition of orthostatic hypotension, neurally mediated syncope and the postural tachycardia syndrome. Freeman R et al., Clin Auton Res. 2011 Apr;21(2):69-72.

10. Fainting. David G. Benditt, MD; MaryAnn Goldstein, MD, Circulation. 2002; 106: 1048-1050

11. National Institute of Neurological Disorders and Stroke Syncope Information Page

12. Fainting and Related Phenomena a Lay Review. Center for Hypotension, New York Medical College, Dr. Julian Stewart, MD, PhD.

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Originally written by Claire Martin, President of Dysautonomia SOS