From the National Institutes of Health, Bethesda, Maryland. For the current author address, see end of text. For definitions of terms used in this article, see glossary at end of text. Acknowledgment: The author thanks B.J. Hessie for skillful editing. Requests for Reprints: Marinos C. Dalakas, MD, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 10, Room 4N248, 10 Center Drive, MSC 1382, Bethesda, MD 20892-1382.
High-dose intravenous immune globulin (IVIg) has emerged as an important therapy for various neurologic diseases. Different interpretations of clinical trial results; the expected benefit of IVIg compared with that of alternate therapies; and issues about IVIg's safety, cost, and mechanisms of action have raised concern and uncertainty among practitioners. To clarify these areas, this paper examines the clinical, serologic, and immunologic data on more than 110 patients with various autoimmune neurologic diseases who received IVIg during the past 6 years at the National Institute of Neurological Disorders and Stroke. It also reviews work by other investigators on the efficacy, risks, benefits, and mechanisms of the action of IVIg in these diseases.
In controlled clinical trials, IVIg has been effective in treating the Guillain-Barre syndrome, multifocal motor neuropathy, chronic inflammatory demyelinating polyneuropathy, and dermatomyositis. In other controlled or open-label trials and case reports, IVIg produced improvement in several patients with the Lambert-Eaton myasthenic syndrome and myasthenia gravis but had a variable, mild, or unsubstantiated benefit in some patients with inclusion-body myositis, paraproteinemic IgM demyelinating polyneuropathy, certain intractable childhood epilepsies, polymyositis, multiple sclerosis, optic neuritis, and the stiff-man syndrome. The primary adverse reaction was headache; aseptic meningitis, skin reactions, thromboembolic events, and renal tubular necrosis occurred rarely. The most relevant immunomodulatory actions of IVIg, operating alone or in combination, are inhibition of complement deposition, neutralization of cytokines, modulation of Fc-receptor-mediated phagocytosis, and down-regulation of autoantibody production. Therapy with IVIg is effective for certain autoimmune neurologic diseases, but its spectrum of efficacy has not been fully established. Additional controlled clinical trials are needed.By the American College of Physicians
Intravenous Immunoglobulin in Autoimmune Neuromuscular Diseases
Author Affiliations: Neuromuscular Diseases Section, National Institutes of Health, National Institute of Neurological Disorders and Stroke, Bethesda, Md.
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. http://jama.ama-assn.org/content/291/19/2367.abstract
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