Summary

• A chronic autoimmune disorder of the post-synaptic membrane at the neuromuscular junction in skeletal muscle.
• Characterised by muscle weakness that increases with exercise (fatigue) and improves on rest. Commonly presents with drooping eyelids, double vision, oropharyngeal and/or appendicular weakness, and shortness of breath.
• Elevated serum acetylcholine receptor antibody titres or muscle-specific tyrosine kinase antibodies are present. Clinical electrophysiology shows decremental response on repetitive nerve stimulation or increased jitter on single-fibre study.
• Treatments include anticholinesterases and immunotherapy. Thymectomy may be required.
• Approximately 15% to 20% of patients may experience a myasthenic crisis (exacerbation necessitating mechanical ventilation).
• Most patients enjoy good quality of life and normal lifespan due to advances in diagnosis and immunosuppressive treatment.