Myasthenia gravis and IVIG (intravenous immunoglobulin)

Deep Dive

For clinicians, IVIG occupies a clear niche in the modern management of myasthenia gravis. When a patient presents with an acute exacerbation—pa... For clinicians, IVIG occupies a clear niche in the modern management of myasthenia gravis. When a patient presents with an acute exacerbation—particularly with bulbar or respiratory compromise—rapid immunomodulation is required while symptomatic agents and maintenance immunotherapies are adjusted. High‑dose IVIG provides a prompt, temporary reduction in pathogenic IgG activity. Mechanistically, pooled immunoglobulin exerts anti‑idiotypic effects, saturates Fc‑mediated recycling pathways that prolong autoantibody survival, down‑regulates activating Fc receptors, and inhibits complement deposition at the neuromuscular junction. The net result is a clinically meaningful improvement in strength, often beginning within several days and persisting for several weeks. Randomized trials and systematic reviews support this short‑term benefit. In head‑to‑head comparisons, plasma exchange (PLEX) often achieves improvement slightly faster, but at the cost of invasiveness, central access, and hemodynamic considerations; IVIG offers comparable functional gains with easier logistics in many centers. Consensus guidelines therefore endorse either IVIG or PLEX for crisis/exacerbation, with choice tailored to urgency, vascular access, comorbidities, and local expertise. By contrast, long‑term maintenance IVIG is generally not first‑line. The evidence base for sustained disease control with periodic infusions is limited, and the therapy carries cumulative costs, infusion burden, and recognized risks including thromboembolism, hemolysis, aseptic meningitis, and kidney injury—particularly in patients with vascular or renal risk profiles. Nevertheless, maintenance IVIG or subcutaneous immunoglobulin can be considered in refractory cases or when conventional steroid‑sparing agents (e.g., azathioprine, mycophenolate) and biologics are contraindicated or ineffective. The therapeutic landscape is rapidly evolving. Complement inhibitors (eculizumab/ravulizumab) and neonatal Fc receptor (FcRn) blockers (efgartigimod/rozanolixizumab) provide targeted options for refractory AChR‑positive MG and may reduce reliance on recurrent IVIG in some patients. Phenotyping matters: MuSK‑positive MG often responds better to PLEX and B‑cell–directed approaches (e.g., rituximab). Safety practice emphasizes pre‑infusion assessment (renal function, thrombotic risk, product selection), careful infusion protocols, and post‑infusion monitoring for hemolysis or aseptic meningitis. Access considerations—payer authorization, site‑of‑care policies, and product availability—also influence real‑world selection and timing of IVIG.