Differential Diagnosis for Sudden Loss of Consciousness

• Single most likely diagnosis:
  • Vasovagal Syncope: This is the most common cause of sudden loss of consciousness, often triggered by emotional stress, pain, or prolonged standing, leading to a sudden drop in blood pressure and heart rate.
• Other Likely diagnoses:
  • Cardiac Arrhythmias: Conditions such as atrial fibrillation or ventricular tachycardia can lead to sudden loss of consciousness due to inadequate blood flow to the brain.
  • Seizures: Generalized seizures can cause a sudden loss of consciousness, often accompanied by convulsions.
  • Hypoglycemia: Low blood sugar can lead to confusion, loss of consciousness, and even seizures if not promptly treated.
• Do Not Miss diagnoses:
  • Stroke or Transient Ischemic Attack (TIA): Although less common, a stroke or TIA can cause sudden loss of consciousness and is critical to diagnose promptly to initiate appropriate treatment.
  • Pulmonary Embolism: A blockage in one of the arteries in the lungs can lead to sudden loss of consciousness due to the inability of the heart to pump enough blood.
  • Aortic Dissection: A tear in the inner layer of the aorta can lead to a sudden drop in blood pressure, causing loss of consciousness.
• Rare diagnoses:
  • Subarachnoid Hemorrhage: Bleeding into the space surrounding the brain can cause sudden, severe headache and loss of consciousness.
  • Meningitis or Encephalitis: Infections of the meninges or brain can lead to sudden loss of consciousness, along with fever, headache, and stiff neck.
  • Hyperthermia or Hypothermia: Extreme body temperatures can cause loss of consciousness due to the body's inability to regulate its internal temperature properly.