Penicillamine-associated myasthenia gravis

Area of Science:

• Neurology
• Rheumatology
• Clinical Immunology

Background:

• Penicillamine is a chelating agent used to treat rheumatoid arthritis and Wilson's disease.
• Myasthenia gravis (MG) is a chronic autoimmune neuromuscular disease characterized by fluctuating muscle weakness.
• Penicillamine-associated MG is a rare but recognized complication of penicillamine therapy.

Observation:

• A patient with rheumatoid arthritis developed clinical and electrodiagnostic signs of MG 7 months after starting penicillamine.
• Electromyography, including single-fiber electromyography, showed abnormalities consistent with MG.
• The patient's condition improved significantly after discontinuing penicillamine.

Findings:

• Clinical improvement correlated with improved electrodiagnostic studies.
• Serum antibody titers to acetylcholine receptors decreased.
• Lymphocyte responsiveness to phytohemagglutinin improved after penicillamine withdrawal.

Implications:

• Penicillamine-associated MG appears to be a distinct clinical entity.
• The syndrome is characterized by a favorable prognosis and high remission rate upon drug cessation.
• Early recognition and discontinuation of penicillamine are crucial for managing this condition.