Intravenous immunoglobulin for myasthenia gravis

Abstract

Myasthenia gravis is an autoimmune disease in which autoantibodies interfere with neuromuscular transmission. As with other autoimmune diseases, people with myasthenia gravis would be expected to benefit from intravenous immunoglobulin (IVIg). The objective of this review was to examine the efficacy of intravenous immunoglobulin for treating exacerbations of myasthenia gravis or for chronic myasthenia gravis. We searched the Cochrane Neuromuscular Disease GroupTrials Register (April 2007) and MEDLINE (January 1966 to May 2007) using 'myasthenia gravis' and 'intravenous immunoglobulin' as the search terms. We included all randomised or quasi-randomised trials in which intravenous immunoglobulin was compared with no treatment, placebo or plasma exchange, in people with myasthenia gravis. One review author extracted the data and two others checked these data and the source from which they were derived. For methodological reasons, no formal meta-analysis was performed. We identified six randomised controlled trials, all of which investigated short-term benefit. A trial of IVIg compared with placebo including 51 patients provided evidence for the effectiveness of IVIg in myasthenia gravis worsening. A study of 87 participants with exacerbation found no statistically significant difference between immunoglobulin and plasma exchange after two weeks. A study of 12 participants with moderate or severe myasthenia gravis treated in a crossover design trial found no statistically significant difference in the efficacy of immunoglobulin and plasma exchange after four weeks. A study with 15 participants with mild or moderate myasthenia gravis found no statistically significant difference in efficacy of IVIg and placebo after six weeks. A study included 33 participants with moderate exacerbations of myasthenia gravis and showed no statistically significant difference in the efficacy of IVIg and methylprednisolone. The last trial including 173 people with myasthenia gravis exacerbations, showed no superiority of IVIg 1 g/kg on two consecutive days over IVIg 1 g/kg on a single day. In exacerbation of myasthenia gravis, one randomised controlled trial of IVIg versus placebo demonstrated the efficacy of IVIg and another did not show a significant difference between IVIg and plasma exchange. Another showed no significant difference in efficacy between 1 g/kg and 2 g/kg of IVIg. A further, but underpowered, trial showed no significant difference between IVIg and oral methylprednisolone. In chronic myasthenia gravis, there is insufficient evidence from randomised trials to determine whether IVIg is efficacious. More research is needed to determine whether IVIg reduces the need for corticosteroids as suggested by two case series.