Immunomodulation is effective in treating patients with myasthenia gravis (MG), but prior studies have not adequately defined if plasma exchange (PLEX) in superior to intravenous immunoglobulin (IVIG) in the treatment of myasthenia gravis. This study aimed to determine if PLEX was superior to IVIG in the treatment of patients with myasthenia gravis.

Patients with MG requiring immunomodulation are randomized to IVIG or PLEX and treated with a full course of immunomodulation. The quantitative myasthenia gravis score (QMGS) will be evaluated as the primary efficacy parameter at day 14 to determine if PLEX is superior to IVIG.

Inclusion Criteria:

• >18 years old
• diagnosis of moderate-severe MG (defined as a Quantitative Myasthenia Gravis Score QMGS >10.5)
• worsening weakness requiring a change in therapy judged by a neuromuscular expert

Exclusion Criteria:

• Worsening weakness secondary to concurrent medications (e.g. Aminoglycosides)
• Worsening weakness secondary to infection
• Change in corticosteroid dosage in the 2 weeks prior to screening
• Other disorders causing weakness or fatigue
• Known absolute IgA deficiency (risk of anaphylactic reaction to IVIG)
• History of anaphylaxis or severe systemic response to IVIG or albumin
• Pregnancy or breastfeeding
• Active renal failure precluding volume of IVIG (risk of volume overload with IVIG) as judged by the investigators
• Clinically significant cardiac disease precluding IVIG volume as judged by the investigators
• Known hyperviscosity or hypercoaguable state (risk of stroke with IVIG)
• Known coagulopathy with bleeding
• On another current study medication or protocol within 4 weeks of screening
• Patients with known refractory status to either IVIG or PLEX
• Poorly controlled or severe hypertension (exacerbation by IVIG)
• Patient refuses treatment with either IVIG or PLEX
• Patient refuses follow-up with electrophysiological studies
• Patient unable or unwilling to give informed consent