Differential Diagnosis for Seizures or Syncope

The following differential diagnosis is organized into categories to help guide the thought process:

• Single Most Likely Diagnosis

  • Epilepsy or seizure disorder: This is often the most likely diagnosis for seizures, as it is a common condition that can cause recurrent seizures.
  • Vasovagal syncope: This is a common cause of syncope, especially in young adults, and is often triggered by stress, pain, or prolonged standing.

• Other Likely Diagnoses

  • Migraine or other headache disorders: Some types of migraines can cause symptoms that resemble seizures or syncope.
  • Orthostatic hypotension: This condition can cause syncope due to a drop in blood pressure when standing up.
  • Cardiac arrhythmias: Certain arrhythmias, such as supraventricular tachycardia or ventricular tachycardia, can cause syncope.
  • Hypoglycemia: Low blood sugar can cause symptoms that resemble seizures or syncope.

• Do Not Miss Diagnoses

  • Cardiac conditions: Conditions such as cardiac tamponade, pulmonary embolism, or aortic dissection can cause syncope and are life-threatening if missed.
  • Stroke or transient ischemic attack (TIA): Although less common, stroke or TIA can cause symptoms that resemble seizures or syncope.
  • Subarachnoid hemorrhage: This is a life-threatening condition that can cause sudden onset of symptoms, including syncope or seizure-like activity.
  • Intracranial hemorrhage: Similar to subarachnoid hemorrhage, intracranial hemorrhage can cause sudden onset of symptoms, including syncope or seizure-like activity.

• Rare Diagnoses

  • Narcolepsy: This condition can cause sudden loss of muscle tone, which may be mistaken for syncope or seizures.
  • Pseudoseizures or psychogenic non-epileptic seizures: These are events that resemble seizures but are not caused by abnormal electrical activity in the brain.
  • Mitochondrial disorders: Certain mitochondrial disorders, such as MELAS syndrome, can cause seizures or syncope-like symptoms.
  • Autoimmune disorders: Conditions such as autoimmune encephalitis or Hashimoto's encephalopathy can cause seizures or syncope-like symptoms.