Definition

1. Transient LOC and loss of posture secondary to insufficient cerebral perfusion.
2. Common – >25% lifetime incidence, 1% ED presentations
3. Incidence increases with age

Causes

1. Up to 50% no cause found.
2. Important to differentiate between seizure & syncope.

Reflex

1. Vasovagal – unexpected/unpleasant sensation, pain, prolonged enclosed standing/kneeling
2. Situational – straining against a closed glottis (cough, micturition, defecation, swallow, trigeminal neuralgia)
3. Carotid sinus syndrome (head turning, tight collar)
4. Breath holding attacks in paeds

Cardiac

1. Structural – valvular, AS (Stokes Adam attack – fixed CO with exercise), TS, MS, cardiomyopathy, pulm HT, CHD, myxoma, pericardial, PE, AMI, dissection
2. Arrhythmias – brady, Mobitz II 2nd deg or 3rd deg block, VT, SVT, AF/flutter, Brugada syndrome, long QT, sinus pause
3. Pacemaker failure

Orthostatic Hypotension

1. Hypovolaemia – haemorrhage (AAA, GI, trauma), Addisonian crisis, fluid loss (burns, D/V, third space, dehydration)

Medication

1. Cardiac – BB, dig, CCB, nitrates, diuretics, anti-HT
2. Other –, anti-psychotics (phenothazines), anti-depressants, anti-Parkinsons
3. Party – cocaine, alcohol, sidenafil

Neurologic

1. TIA, migraine, SAH, Shy-Drager,(seizure – DDx), subclavian steal syndrome

Psychiatric

1. Up to 50% in young adults_

Other

1. Anaemia, hypoglycaemia_

Assessment

1. Preceeding events often key to making a diagnosis:
2. Position/Env – prolonged standing (reflex), on standing (orthostatic), stress (vasovagal)
3. Sweating, lightheadedness, nausea (vasovagal or orthostatic)
4. Chest pain, palpitations or sudden onset without prodrome (cardiac/arrhythmia)
5. Exertion (AS, HOCM, VT, long QT)
6. Upper limb exercise (subclavian steal syndrome)
7. Head turning, neck compression, shaving (carotid sinus syncope)
8. Distinguish from seizures (tonic-clonic movements, longer LOC, post-ictal, tongue biting)
9. Past medical history of syncope, cardiac disease
10. Family history of sudden cardiac death
11. Medications/drugs used

Examination

1. Vitals – Difference in pulses/BP in arms (subclavian steal, dissection). Orthostatic hypotension – symptomatic drop BPsys ≥20mm on standing from supine.
2. CVS – murmurs, added heart sounds
3. Resp – SOB
4. Abdo – PR – occult GI haemorrhage
5. Neuro – any defcits
6. Injuries from syncope
7. Autonomic dysfunction – impotence, anhydrosis, sphincter dysfunction (Shy Drager)

Investigations

Bedside

1. ECG
2. BSL

Lab testing – limited value

1. Troponin not useful unless CP or abnormal ECG
2. FBC if clinically anaemic or blood loss suspected.
3. βhCG

Imaging

1. CXR, ECHO if cardiac cause suspected

ED Provocation tests (not routinely done)

1. Carotid sinus massage
2. Hyperventilation (psych cause)

Outpatient

1. Tilt table testing
2. Holter monitor

Treatment

1. Treat underlying cause
2. Consider admission for possible cardiac cause, significant bleeding, unsupervised social situation, or high risk

Syncope CHESS Rule

1. 2004 San Francisco Rules for short term (7-30d) serious outcome (death, MI, arrhythmia, PE, CVA, SAH, transfusion, return ED visit) risk (96% sens, 62% spec) in undifferentiated syncope:
2. Risk factors:
   1. CCF
   2. Haematocrit<30%
   3. ECG abnormal
   4. SOB
   5. Systolic BP<90mmHg at triage
3. Some validation studies of CHESS rule have shown considerably less sensitivity & specificity, but other studies have identified (1) age >65 years; (2) history of CCF; (3) an abnormal ECG as consistent high risk factors. So reasonable to stratify as high risk on CHESS criteria and 2 extra factors Elderly and Family Hx of sudden death.

Prognosis

1. Syncope
   • +cardiac cause=2xmort,
   • +neuro cause=1.5xmort,
   • +unknown=1.3xmort,
   • +reflex=<1xmort.