Myasthenia Graves (MG) is a chronic, autoimmune disorder which causes voluntary (skeletal) muscle weakness.
In MG, antibodies block, destroy, or alter acetylcholine receptors at the neuromuscular junction (NMJ), which impedes nerve conduction to the muscle.
The hallmark of MG is weakness, classically of the muscles controlling bulbar function, mastication, neck movement, and facial expression, that worsens with activity and improves with rest.
A true MG crisis ensues once respiratory muscles weaken to the point of requiring assisted ventilation. Such a medical emergency can be triggered by fever, infection, or an adverse reaction to medication.
Edrophonium chloride (or Tensilon) can be administered intravenously to confirm the diagnosis of an MG attack. This drug increases levels of acetylcholine at the NMJ and temporarily relieves the symptoms of an MG.
Assisted ventilation, plasmpharesis, and high dose IV immune globulin can all be used to treat an acute MG crisis.
MG can chronically be controlled with anticholinesterase agents such as neostigmine and pyridostigmine, as well as immunosuppressives such as prednisone, cyclosporine, and azathioprine. Thymectomy is also a surgical treatment option.