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
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
Rules identifying higher risk and warrant admission:
ROSE rule - BRACES admit if any of the following:
- BNP ≥300pg/ml, Bradycardia ≤50
- Rectal blood
- Anaemia ≤90
- Chest pain
- ECG with Q wave except III
- Saturation ≤94% room air
San Francisco Syncope Rule - CHESS criteria admit if any of the following:
- Congestive Heart Failure History
- Hematocrit <30%
- ECG Abnormal?
- Shortness of Breath History?
- sBP <90 mmHg at Triage
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