Intravenous immunoglobulin for myasthenia gravis.

Abstract

Myasthenia gravis is an autoimmune disease. In up to 90 per cent of cases IgG autoantibodies to the nicotinic acetylcholine receptor are detectable which mediate the neuromuscular transmission disorder. As with other autoimmune diseases, patients would be expected to benefit from intravenous immunoglobulin. Case series and two randomised controlled trials suggest that intravenous immunoglobulin may be beneficial. The objective of this review is to examine the efficacy of intravenous immunoglobulin for treating exacerbations of myasthenia gravis or for chronic myasthenia gravis. We searched the Cochrane Neuromuscular Disease Group trials register (21 July 2002) and MEDLINE (January 1966 to July 2002) using 'myasthenia gravis' and 'intravenous immunoglobulin' as the search terms. All randomised or quasi-randomised trials in which intravenous immunoglobulin was compared with no treatment, placebo or plasma exchange, in people with myasthenia gravis who were diagnosed by an internationally accepted definition. One author extracted the data and the two others checked these data and the source from which they were derived. For methodological reasons, no formal meta-analysis was performed. We identified four randomised controlled trials (147 participants in total), all investigating short-term benefit. In the first study of 87 people with myasthenia gravis exacerbation, comparing intravenous immunoglobulin and plasma exchange, there was no statistically significant difference between the efficacy of the two treatments after two weeks. In the second study 12 people with moderate or severe myasthenia gravis were treated in a cross-over design trial with intravenous immunoglobulin or plasma exchange: no statistically significant difference in the efficacy of the two treatments was found after four weeks. In the third study 15 people with mild or moderate myasthenia gravis received intravenous immunoglobulin or a placebo: no significant difference in efficacy of intravenous immunoglobulin or placebo was found six weeks after treatment. The last study, which included 33 people with moderate exacerbations of myasthenia gravis, compared intravenous immunoglobulin and methylprednisolone and showed no statistically significant difference in the efficacy of the two treatments. One randomised controlled trial did not show a significant difference between intravenous immunoglobulin and plasma exchange for treatment of severe exacerbations of myasthenia gravis. There is no evidence from randomised controlled trials to determine whether intravenous immunoglobulin for moderate or severe myasthenia gravis improves functional outcome or has a sparing effect on steroid dosage, nor is there sufficient evidence to favour intravenous immunoglobulin over steroids in moderate exacerbations. Further randomised controlled trials are needed.