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5. Myasthenia gravis crisis
Myasthenia gravis (MG) is an autoimmune syndrome characterized by dysfunction of neuromuscular junction transmission due to autoantibody attack on the post-synaptic terminal. Patients often present with symptoms of fatigable weakness of bulbar, ocular and appendicular muscles. Weak cough (and difficulty handling secretions) and use of accessory breathing muscles are typical warning signs of imminent respiratory failure in MG.
MG can be difficult to distinguish from other causes of muscle weakness. Hypothyroidism typically presents as fatigue, constipation, cold intolerance and arthralgias/myalgias rather than muscle weakness. ALS typically presents with asymmetric limb weakness with hyperreflexia and spasticity, along with muscle atrophy and fasciculations; dysarthria and dysphagia may also be present. GBS presents as acute development of diffuse weakness and areflexia. LEMS is typically slowly progressive proximal (leg > arm) muscle weakness with autonomic dysfunction such as dry mouth, sluggish pupillary light reflex, and impotence. LEMS is unique as can see improvement in muscle strength with brief vigorous muscle activation.
What is the usual work up for this constellation of symptoms? (Click on the correct answer to proceed to the next panel).