Definition
- Transient LOC and loss of posture secondary to insufficient cerebral perfusion.
- Common – >25% lifetime incidence, 1% ED presentations
- Incidence increases with age
Causes
- Up to 50% no cause found.
- Important to differentiate between seizure & syncope.
Reflex
- Vasovagal – unexpected/unpleasant sensation, pain, prolonged enclosed standing/kneeling
- Situational – straining against a closed glottis (cough, micturition, defecation, swallow, trigeminal neuralgia)
- Carotid sinus syndrome (head turning, tight collar)
- Breath holding attacks in paeds
Cardiac
- Structural – valvular, AS (Stokes Adam attack – fixed CO with exercise), TS, MS, cardiomyopathy, pulm HT, CHD, myxoma, pericardial, PE, AMI, dissection
- Arrhythmias – brady, Mobitz II 2nd deg or 3rd deg block, VT, SVT, AF/flutter, Brugada syndrome, long QT, sinus pause
- Pacemaker failure
Orthostatic Hypotension
- Hypovolaemia – haemorrhage (AAA, GI, trauma), Addisonian crisis, fluid loss (burns, D/V, third space, dehydration)
Medication
- Cardiac – BB, dig, CCB, nitrates, diuretics, anti-HT
- Other –, anti-psychotics (phenothazines), anti-depressants, anti-Parkinsons
- Party – cocaine, alcohol, sidenafil
Neurologic
- TIA, migraine, SAH, Shy-Drager,(seizure – DDx), subclavian steal syndrome
Psychiatric
- Up to 50% in young adults_
Other
- Anaemia, hypoglycaemia_
Assessment
- Preceeding events often key to making a diagnosis:
- Position/Env – prolonged standing (reflex), on standing (orthostatic), stress (vasovagal)
- Sweating, lightheadedness, nausea (vasovagal or orthostatic)
- Chest pain, palpitations or sudden onset without prodrome (cardiac/arrhythmia)
- Exertion (AS, HOCM, VT, long QT)
- Upper limb exercise (subclavian steal syndrome)
- Head turning, neck compression, shaving (carotid sinus syncope)
- Distinguish from seizures (tonic-clonic movements, longer LOC, post-ictal, tongue biting)
- Past medical history of syncope, cardiac disease
- Family history of sudden cardiac death
- Medications/drugs used
Examination
- Vitals – Difference in pulses/BP in arms (subclavian steal, dissection). Orthostatic hypotension – symptomatic drop BPsys ≥20mm on standing from supine.
- CVS – murmurs, added heart sounds
- Resp – SOB
- Abdo – PR – occult GI haemorrhage
- Neuro – any defcits
- Injuries from syncope
- Autonomic dysfunction – impotence, anhydrosis, sphincter dysfunction (Shy Drager)
Investigations
Bedside
- ECG
- BSL
Lab testing – limited value
- Troponin not useful unless CP or abnormal ECG
- FBC if clinically anaemic or blood loss suspected.
- βhCG
Imaging
- CXR, ECHO if cardiac cause suspected
ED Provocation tests (not routinely done)
- Carotid sinus massage
- Hyperventilation (psych cause)
Outpatient
- Tilt table testing
- Holter monitor
Treatment
- Treat underlying cause
- Consider admission for possible cardiac cause, significant bleeding, unsupervised social situation, or high risk
Syncope CHESS Rule
- 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:
- Risk factors:
- CCF
- Haematocrit<30%
- ECG abnormal
- SOB
- Systolic BP<90mmHg at triage
- 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
- Syncope
- +cardiac cause=2xmort,
- +neuro cause=1.5xmort,
- +unknown=1.3xmort,
- +reflex=<1xmort.