Differential Diagnosis for Autoimmune Disorder Causing Recurrent Syncope

• Single Most Likely Diagnosis
  • Postural Orthostatic Tachycardia Syndrome (POTS): Often associated with autoimmune disorders and can cause recurrent syncope due to abnormal heart rate and blood pressure regulation upon standing.
• Other Likely Diagnoses
  • Lupus: Systemic lupus erythematosus can cause a wide range of symptoms including syncope due to its effects on various body systems, including the cardiovascular system.
  • Rheumatoid Arthritis: Though less common, rheumatoid arthritis can lead to syncope through mechanisms like inflammation affecting the heart or through medication side effects.
  • Sjögren's Syndrome: This autoimmune disorder can cause syncope indirectly through its effects on the nervous system or through associated conditions like POTS.
• Do Not Miss Diagnoses
  • Autoimmune Autonomic Ganglionopathy: A rare condition that affects the autonomic nervous system, leading to severe orthostatic hypotension and potentially life-threatening syncope if not promptly recognized and treated.
  • Multiple System Atrophy: Although not strictly an autoimmune disorder, it can present with autonomic dysfunction leading to syncope and has a poor prognosis if missed.
• Rare Diagnoses
  • Autoimmune Encephalitis: Certain forms can lead to autonomic dysfunction, including syncope, though this is less common and usually part of a broader neurological presentation.
  • Paraneoplastic Syndromes: These are rare autoimmune disorders triggered by cancer, which can cause a variety of neurological symptoms including syncope, though they are uncommon and usually associated with a known or newly diagnosed malignancy.