Syncope

Syncope is often referred to by patients as “fainting” and is defined as a loss of postural tone and consciousness. Syncope usually lasts for brief periods of a few minutes. Longer periods are of more concern, because of the possibility of major cardiac or neurologic problems. The patient's and other observer's descriptions of symptoms immediately before and after the episode are key to determining the etiology of the syncopal episode. Particularly in healthy children and adults, vasovagal syncope from decreased cerebral blood flow is the most common type of brief syncopal episode.

Differential Diagnosis

• Vasovagal episode
  –Most common cause of syncope
  –May be triggered by heat, fatigue, stress, hunger, alcohol, and severe pain
  –Associated with diaphoresis, weakness, blurry vision, lightheadedness
  –Almost always benign
• Orthostatic hypotension
  –Fall in blood pressure upon standing, due to failure of vasoconstrictor reflexes
  –Precipitated by sudden standing from recumbent position
  –Often associated with antihypertensive medications (diuretics, vasodilators, α - or β-blockers) and dehydration/hypovolemia
  –May occur with autonomic disorders (e.g., Shy-Drager syndrome)
  • Situational syncope
    –Increased intrathoracic pressure (e.g., cough, micturition, defecation) leads to decreased venous return and resulting diminished blood flow to the brain
  • Cardiac arrhythmias
    –Very slow (<30 bpm) or fast (>180 bpm) heart rates may result in decreased cardiac output and resulting diminished blood flow to the brain
• Valvular disease
  –Most commonly due to aortic stenosis
• Myocardial disease
• Cerebrovascular disease
  –Usually due to carotid or vertebrobasilar atherosclerosis
• Hypoglycemia
• Anemia
• Seizure
• Anxiety attack
• Migraine
• Medications (e.g., anticholinergics)
• CVA
• Hemorrhage
• Trauma

Workup and Diagnosis

• History and physical exam will often suggest the underlying etiology
  –Note pre- and postsyncopal symptoms (e.g., chest pain, dizziness, lightheadedness, nausea/vomiting, headache, diaphoresis, blurry vision, blindness)
  –Full HEENT, neurologic, and cardiovascular exam
  –Examine for trauma following syncope
  –Record BP in supine, sitting, standing, and in both arms
  –Strategically attempt to reproduce syncope by Valsalva maneuver (e.g., coughing, deep breathing for 2–3 min)
• Initial labs should include CBC, electrolytes, calcium, magnesium, glucose, toxicology screens, and ECG
• Further cardiovascular testing may include cardiac enzymes if ischemia is suspected, 24-hour Holter monitor, echocardiogram, stress testing, and/or invasive cardiac monitoring
• Head CT to rule out cerebral disease
• Doppler ultrasound of carotids if bruit is heard
• EEG may be useful if seizure disorder is suspected
• Tilt table test may induce vasovagal episode
• Plasma aldosterone/mineralocorticoid levels to evaluate for hypovolemia due to adrenocortical insufficiency

Treatment

• Identify, treat, and/or refer on the basis of underlying cardiac, neurologic, autonomic or other causes
• Vasovagal episode: Rehydrate, treat possible triggers (e.g., relieve pain)
• Orthostatic hypotension: Adjust medications, make lifestyle changes (e.g., rise slowly from sitting)
• Cardiac arrhythmias: Medical management and/or pacemaker placement
• Myocardial disease/valvular disease: Assess severity, consider medical versus surgical treatment
• Cerebrovascular disease: Reduce risk factors; consider medical versus surgical treatment
• Hypoglycemia: Identify underlying cause; adjust medications and diet to prevent further episodes
• Seizures: Adjust medications to prevent seizures; no driving

Book Source Details

• Book Title: In a Page: Signs and Symptoms
• Author(s): Scott Kahan, Ellen G. Smith
• Year of Publication: 2004
• Copyright Details: In a Page: Signs and Symptoms, Copyright © 2004 Lippincott Williams & Wilkins.

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Copyright Details: In a Page: Signs and Symptoms, Copyright © 2008 Williams & Wilkins.

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• Back to symptom: Dizziness: Introduction (review 1275 causes)
• Next Book Extract About Dizziness: Dizziness/Lightheadedness & Vertigo (In a Page: Signs and Symptoms)
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More About This Book: Title: In a Page: Signs and Symptoms Authors: Scott Kahan, Ellen G. Smith Publisher: Lippincott Williams & Wilkins Copyright: 2004 ISBN: 1-4051-0368-X

 » Next page: Dizziness/Lightheadedness & Vertigo (In a Page: Signs and Symptoms)

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