Acute loss of consciousness

Differential

• Syncope: insufficient cerebral perfusion
  • Cardiac
    • Cardiac arrhythmia (including tachyarrhythmias and bradyarrhythmias), which commonly occurs without prodrome, during physical exertion, or in patients with known heart disease
      • Complete heart block
      • Atrial fibrillation
      • Supraventricular tachycardia
      • Ventricular tachycardia
    • Cardiac outflow obstruction, commonly characterized as exertional syncope with a murmur
      • Severe aortic stenosis
      • Hypertrophic cardiomyopathy
      • Atrial myxoma
      • Pulmonary hypertension
      • Pulmonary embolism
      • Aortic dissection
  • Hypotension
    • Vasovagal syncope
    • Orthostatic hypotension
• Seizure, which may have prolonged loss of consciousness, lateral tongue biting, postictal confusion, and an aura
• Hypoglycemia
• Psychogenic nonepileptic seizures
• Subarachnoid hemorrhage, usually preceded by thunderclap headache
• Acute hydrocephalus (acute increase in ICP)
• Transient ischemic attack, particularly involving the brain stem reticular activating system (vertebrobasilar) when no other focal neurological symptoms
• Narcolepsy
• Drug toxicity or overdose