A 32-year-old man presents with acute onset ascending paralysis and areflexia 10 days after a diarrheal illness. CSF analysis shows elevated protein (120 mg/dL) with normal cell count. Nerve conduction studies confirm demyelinating features. What is the drug of choice for this patient?

Explanation

## First-Line Immunotherapy in GBS **Key Point:** IVIG and plasma exchange are the two evidence-based first-line treatments for Guillain-Barré Syndrome; IVIG is preferred in most settings due to ease of administration and availability. ### Mechanism of IVIG in GBS 1. Blocks pathogenic autoantibodies (anti-ganglioside antibodies) 2. Modulates complement activation 3. Suppresses macrophage-mediated demyelination 4. Reduces inflammatory cytokine production ### Dosing and Efficacy - **Standard dose:** 2 g/kg total, given as 0.4 g/kg daily for 5 days - **Onset:** Clinical improvement typically within 3–7 days - **Efficacy:** Reduces time to independent ambulation by ~50% when started within 2 weeks of symptom onset **High-Yield:** IVIG is preferred over plasma exchange in most centres because: - Easier vascular access (peripheral IV acceptable) - No need for specialized equipment or anticoagulation - Fewer haemodynamic fluctuations - Can be given in non-ICU settings ### When Plasma Exchange May Be Preferred - Severe, rapidly progressive disease requiring urgent intervention - Respiratory failure imminent - IVIG contraindicated (IgA deficiency, thrombosis risk) - Early presentation (< 7 days) with severe disability **Clinical Pearl:** Combination IVIG + plasma exchange offers no additional benefit over monotherapy and is not recommended [cite:Harrison 21e Ch 446]. ### Treatment Timeline - **Acute phase (0–4 weeks):** IVIG or plasma exchange - **Plateau phase (2–4 weeks):** Supportive care, respiratory monitoring - **Recovery phase (weeks to months):** Rehabilitation; no further immunotherapy needed