Angioneurotic Oedema
📖 About
- Angioneurotic Oedema (Angioedema): Sudden, transient swelling of the deeper dermis, subcutaneous tissue, or mucosa.
- Can be allergic (histamine-mediated) or due to C1-esterase inhibitor (C1-INH) deficiency (hereditary or acquired).
- Commonly involves the lips, tongue, face, and airway, risking life-threatening obstruction.
- May also affect the gastrointestinal tract (abdominal pain, vomiting) or extremities.
🩺 Clinical Features
- With urticaria: Usually allergic, histamine-mediated, often linked with anaphylaxis.
- Without urticaria: Suggests C1-INH deficiency (hereditary/acquired angioedema).
- Swelling develops over hours and resolves over 24–72 hours.
- Airway involvement → stridor, voice change, respiratory distress (medical emergency 🚨).
- Abdominal attacks may mimic an “acute abdomen.”
🧬 Causes
- Idiopathic – no identifiable trigger.
- Allergic/Drug-related – food (shellfish, nuts), medications (ACE inhibitors, NSAIDs, statins).
- Hereditary Angioedema (HAE) – C1-INH deficiency or dysfunction (autosomal dominant).
- Acquired C1-INH deficiency – associated with autoimmune disease (e.g., SLE) or lymphoproliferative malignancies (lymphoma, myeloma).
⚠️ Management
- Airway first – involve anaesthetics/ICU early if obstruction risk.
- Adrenaline (IM) 0.3–0.5 mL of 1:1000 if features suggest anaphylaxis (hypotension, urticaria, bronchospasm).
- Antihistamines & steroids: Useful in allergic angioedema but ineffective in C1-INH deficiency.
- C1-INH concentrate (or bradykinin antagonist, e.g., icatibant) = treatment of choice in hereditary/acquired cases.
- Tranexamic acid: May reduce attack frequency in hereditary angioedema (especially prophylaxis).
- IV hydrocortisone (100–200 mg) – used in allergic-mediated cases; not effective in HAE.
💡 Key Exam Pearl:
- Urticaria present → think allergic/anaphylaxis (histamine-mediated, responds to antihistamines/steroids).
- Urticaria absent → think hereditary/acquired angioedema (C1-INH deficiency, no response to antihistamines/steroids).
