===== Syncope =====

A sudden, transient, self-limited //**loss of consciousness**// with an inability to maintain postural tone that is followed by spontaneous recovery. This definition excludes seizures, coma, shock, or other states of altered consciousness.

Obtaining a thorough Past History is vital to establishing a likely cause. In at least 50% of cases an underlying cause is not found.

**Common categories:**
  *Neurally‐mediated (reflex) syncope - probably around 70%
    *emotional and orthostatic stress
    *associated with other function eg micturition, sneeze, cough, defaecate
    *carotid sinus syncope - when carotid sinus mechanically manipulated
  *Orthostatic hypotension
    *ANS fails to respond to posture changes eg Parkinsons, dementia, diabetes, uremia, spinal injury
    *drug related eg alcohol, vasodilators, antidepressants
    *volume depletion - eg blood loss, D&V, diuretics
  *Cardiac arrhythmias - probably around 10%
    *bradys and tachys, heart block, pacemaker related
  *Structural heart disease
  *'Steal' syndromes
    *rare - eg. subclavian steal syndrome

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=== Prognosis ===
  *various decision rules have been tested and focus on identifying high risk patients. Usually result in over admission:
    *San Francisco Syncope Rule (also known as CHESS criteria)
    *ROSE (Risk stratification of Syncope in ED) - 
  *when pathology seems causative, eg cardiac cause, prognosis is worse
  *vaso-vagal - good prognosis
  *background of cardiac disease has worse prognosis regardless of causation of presenting syncopal episode

=== Pre-syncopal red flags ===
  *exertional onset, chest pain, dyspnea, palpitations
  *low back pain
  *severe headache, focal neurologic deficits, diplopia, ataxia, or dysarthria 

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=== Rules identifying higher risk and warrant admission: ===

** ROSE rule - BRACES ** admit if any of the following:

  ***B**NP ≥300pg/ml, Bradycardia ≤50
  ***R**ectal blood
  ***A**naemia ≤90
  ***C**hest pain
  ***E**CG with Q wave except III
  ***S**aturation ≤94% room air

** San Francisco Syncope Rule - CHESS criteria ** admit if any of the following:

  ***C**ongestive Heart Failure History
  ***H**ematocrit <30%
  ***E**CG Abnormal?
  ***S**hortness of Breath History?
  ***s**BP <90 mmHg at Triage

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===Idiopathic orthostatic hypotension/Pure Autonomic Failure (Bradbury-Eggleston syndrome)===
  *a selective neuropathy of sympathetic and parasympathetic nervous system of unknown aetiology
  *insidious, arising mainly in middle to late age
  *men 5x women
  *no cognitive or central dysfunction
  *impotence, post-prandial problems and nocturia are common
  *wide range of 'vague' autonomic symptoms
  *prodrome of sweating, tachycardia and pallor seen in vasovagal syncope does not occur

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=== References include: ===

[[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1861366/|NCBI diagnosis and treatment of syncope]] \\ 
https://emedicine.medscape.com/article/811669-overview#a3 \\  
[[https://www.sciencedirect.com/science/article/pii/S0735109709039850|J Am Cardiol ROSE study]] \\ 
[[https://www.academia.edu/22930859/Pathophysiology_diagnosis_and_treatment_of_orthostatic_hypotension_and_vasovagal_syncope|Cardiology in Review: Orthostatic hypotension and vasovagal syncope 2008]]\\