Table 2

Non-syncopal conditions presenting with collapse

ConditionFeatures that distinguish from syncope
Cardiac arrestNo spontaneous recovery from TLoC
CataplexyLoss of muscular tone and responsive, usually associated with narcolepsy
ComaLonger duration of LoC without spontaneous recovery
Complex partial seizures, absence epilepsyUnresponsiveness and amnesia without falls, with associated neurological features
Falls without TLoCAbsence of amnesia and unresponsiveness, clear cause for fall
Generalized seizuresAura, flashing lights may trigger, longer duration of LoC, symmetrical rhythmic muscle movements, confusion after LoC lasting minutes (shorter with syncope)
IntoxicationLonger duration of LoC, consciousness often impaired rather than lost
Intracerebral or subarachnoid hemorrhageSevere headache, neurological signs, and progressive LoC
Metabolic disorders (hypoglycaemia, hypoxia, hyperventilation with hypocapnia)Longer duration of LoC, consciousness often impaired rather than lost
Psychogenic pseudosyncopeIncreased frequency and longer duration of apparent syncope without true LoC, maintained hemodynamics, normal electroencephalogram
Subclavian steal syndromeUpper extremity activity associated with focal neurological signs
Transient ischemic attackFocal neurological features usually without TLoC.
If LoC occurs, there is a longer duration of TLoC.
  • Conditions that may be incorrectly diagnosed as syncope are listed, modified from the American College of Cardiology and European Society of Cardiology and syncope guidelines.12 32

  • LoC, loss of consciousness; TLoC, transient loss of consciousness.