This study is a double-blind, placebo-controlled, randomized clinical trial to determine whether IVIG is effective in improving motor scores in patients with myasthenia gravis and worsening weakness.

Patients aged 18 years or older with a diagnosis of myasthenia gravis (MG) and worsening weakness were enrolled in the study after providing informed consent. Fifty-two patients were recruited to the study, but one withdrew consent prior to starting so that 51 patients were recruited. Baseline clinical assessments using the Quantitative MG Score for Disease Severity (QMGS) were repeated at 2 and 4 weeks after treatment with IVIG or saline infusion. The Post-Intervention Status was assessed at 2 and 4 weeks after treatment. The treatment was randomized and double-masked. Electrophysiological and immunological tests were done at baseline and after 2 weeks. Baseline characteristics were compared by the Student's t test for continuous variables or Chi-square test for categorical variables. An analysis of covariance was performed for the primary outcome measure, the change in QMGS.

Inclusion Criteria:

• age > or equal to 18 years old with a confirmed diagnosis of myasthenia gravis and worsening weakness

Exclusion Criteria:

• age <18; severe myasthenia gravis requiring intensive care admission; change in immunosuppresive medication in previous 3 months; patients with severe bulbar weakness at risk for aspiration and respiratory failure; patients with other serious underlying medical conditions (renal failure, congestive heart failure); unwilling to provide informed consent.