Intravenous Immunoglobulin in Autoimmune Neuromuscular Diseases

CONTEXT: Intravenous immunoglobulin (IVIG) enhances immune homeostasis by modulating expression and function of Fc receptors, interfering with activation of complement and production of cytokines, providing anti-idiotypic antibodies, and affecting the activation and effector functions of T and B cells. These mechanisms may explain the effectiveness of IVIG in autoimmune neuromuscular disorders. OBJECTIVE: To systematically review the current status of the treatment of autoimmune neuromuscular diseases with IVIG, with emphasis on controlled trials. DATA SOURCES: Peer-reviewed publications identified through MEDLINE (1966-2003), EMBASE (1974-2003), and references from bibliographies of pertinent articles. Each autoimmune neuromuscular disease term was searched in combination with the term intravenous immunoglobulin. STUDY SELECTION AND DATA EXTRACTION: Criteria for selection of studies included controlled study design, English language, and clinical pertinence. Data quality was based on venue of publication and relevance to clinical care. DATA SYNTHESIS: Outcomes of controlled trials indicate that IVIG at a total dose of 2 g/kg is effective as first-line therapy in Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, and multifocal motor neuropathy and as second-line therapy in stiff-person syndrome, dermatomyositis, myasthenia gravis, and Lambert-Eaton myasthenic syndrome. In other controlled studies, IVIG produced a modest, variable, and transient but not statistically significant benefit in patients with inclusion body myositis and paraproteinemic anti-myelin-associated glycoprotein antibody demyelinating polyneuropathy. Intravenous immunoglobulin is not effective in patients with multiple sclerosis who have established weakness or optic neuritis. In myasthenia gravis, it should be reserved for difficult cases or before thymectomy in lieu of plasma exchange. CONCLUSION: Intravenous immunoglobulin is effective in many autoimmune neurologic diseases, but its spectrum of efficacy, especially as first-line therapy, and the appropriate dose for long-term maintenance therapy are not fully established. Further controlled studies of IVIG, combined with a dose-finding effect, pharmacoeconomics, and quality-of-life assessments, are warranted to improve the evidence base for clinical practice.