Treatment in Lambert-Eaton myasthenic syndrome

Besides antitumor therapy for patients with the paraneoplastic form of Lambert-Eaton myasthenic syndrome (LEMS), the mainstay of symptomatic treatment in LEMS is 3,4-diaminopyridine (3,4-DAP). Data from four randomized, placebo-controlled trials have revealed that muscle strength scores increased significantly with 3,4-DAP. A limited meta-analysis performed on two trials using the Quantitative Myasthenia Gravis score indicated that the clinical benefits seen were modest. Meta-analysis of the mean change in compound muscle action potential amplitude following 3,4-DAP treatment revealed a significant improvement compared to placebo. However, most patients with noncancer LEMS require long-term immunosuppression, usually with prednisolone and azathioprine. A single crossover study has previously shown significant short-term benefit in limb strength following intravenous immunoglobulin, and there are isolated case reports of medium term benefit from rituximab. Overall, a combination of symptomatic treatment with 3,4-DAP and immunosuppression, with or without antitumor therapy, is often successful for most LEMS patients, with other more aggressive regimens rarely needed.