Syncope

It is almost the 2 month countdown to the beginning of my Internal Medicine residency. I am looking forward to not being a medical student anymore but, naturally, I am terrified at the idea of being a physician. It has been very busy around here. We are in the process of sorting and packing up our home while trying to go to our everyday jobs as well. Still, I want to stay true to the spirit of my blog and continue to learn and read no matter how busy life gets. I thought that it would be appropriate to start focusing on common Internal Medicine admission problems to prep for the upcoming excitement! Today's topic...Syncope!

Introduction - Syncope is the abrupt and transient loss of consciousness associated with absence of postural tone, followed by complete and often rapid spontaneous recovery.

There are many causes of syncope but one can sort differentials into most likely vs least likely by taking a detailed history. Questions I ask all of my syncope patients include...

• What were you doing before it happened (laying to sitting to standing position? stressful event? Prolonged standing?)?
• Did you have any flushing, lightheadedness diaphoresis or nausea?
• Did you feel any palpitations?
• Did you lose bowel of bladder control?
• Did you have tremors/shaking?
• Were you short of breath?
• Did you have any chest pain?
• Was it witnessed? If so, what did the patient look like or do when they passed out? How long were they unconscious? Were they confused when they woke up? How long were they confused?
• Did the patient experience any auras before they passed out?
• Patients past medical history (panic attacks with hyperventilation, cardiac conditions or diabetes)
• Any new medications (antiarrhythmics or antihypertensives) or illicit drugs/etoh?
• Recent illness?
• Decreased oral intake?
• Has this ever happened before and if so, what was the circumstance?

Physical Exam

• Blood pressure obtained in the supine, sitting, and erect position may detect orthostatic hypotension
• Heat rate - is it tachy, brady or irregular?
• Resp rate - is the patient hyperventilating?
• Cardiac ascultation
• Neurologic findings such as unilateral neurologic defecits

Causes of Syncope

Vasovagal - Vasovagal syncope (also known as neurocardiogenic syncope) is the most common cause of syncope. Vasovagal syncope may be caused by autonomic cardioinhibitory and/or vasodilator responses. It is likely that sensory inputs through vagal afferents, pain pathways, and central pathways to cause inhibition of the sympathetic nervous system and vagal activation. The most frequent mechanism for vasovagal syncope is a cardioinhibitory response and the most common abnormality was prolonged asystolic pauses and bradycardia. 

Situational - Situational syncope refers to syncope associated with specific scenarios.

Some situations  (postmicturition, cough, or post-tussive) appear to trigger a neural reflex causing a vagal response others (eg, straining, squatting) may cause syncope via mechanisms unrelated to neural reflexes. Several forms of situational syncope are associated with gastrointestinal stimuli (swallowing, defecation, visceral pain).

Orthostatic (Postural) - When autonomic reflexes are impaired or intravascular volume is decreased, a significant reduction in blood pressure occurs upon standing, a phenomenon termed orthostatic hypotension. Orthostatic hypotension can cause dizziness, syncope, and even angina or stroke. Many disorders can cause orthostatic hypotension (Parkinsons, dementia with Lewy bodies and Multiple System Atrophy), volume depletion (blood loss or decreased oral intake) and medications (antihypertensives) are all common causes.

Cardiogenic - Cardiac causes of syncope include structural heart disease leading to abrupt episodic drops in cardiac output by various mechanisms and thus, decreased cerebral perfusion. These conditions may include an abnormal heart rhythm (arrhythmia), obstructed blood flow in the heart or blood vessels, valve disease, aortic stenosis, blood clot, or heart failure

Neurologic - Neurologic syncope is the loss of consciousness due to a neurological condition such as seizure, stroke, transient ischemic attack or other rare causes including migraines and normal pressure hydrocephalus.

What tests should you order?

• Orthostatic Blood Pressures
• Echocardiogram when there is previous known heart disease or data suggestive of structural heart disease or syncope secondary to cardiovascular cause
• Immediate EKG monitoring when there is a suspicion of arrhythmia
• Blood glucose
• CBC/CMP
• In hospital monitoring is recommended if patient has structural heart disease and is determined to be at risk for arrhythmia 
• If a neurologic cause is suspected should get CT or head without contrast or EEG if patient had suspected seizure activity 
• Exercise if exercise induced syncope is suspected
• Psychiatric consult if pseudosyncope is suspected
• Tox screen is high suspicion of drug/alcohol abuse