summary Myasthenia Gravis is a common autoimmune disorder caused by autoantibodies directed against the acetlycholine receptor of the neuromuscular junction. Patients present with fluctuating proximal muscle weakness, ocular symptoms, and dysphagia. Diagnosis is made with serologic testing for anti-AChR autoantibodies. Treatment is medical management with acetylcholinesterase inhibitors. Epidemiology Incidence has a bimodal distribution more common in younger women (< 40 years of age) and older men (> 50 years of age) Risk factors HLA-B8 medications penicillamine aminoglycosides Etiology Pathogenesis autoantibodies directed against a protein of the neuromuscular junction autoantibodies can be directed against login to view 3 more bullets categorized as a type II hypersensitivity reaction T-cells play a role as well thought to stimulate B-cell antibody production Associated conditions thymoma thymic hyperplasia Presentation Symptoms general feature fluctuating muscle weakness login to view 2 more bullets true muscle fatigue login to view 1 more bullet ocular symptoms most common presenting symptoms login to view 2 more bullets bulbar symptoms dysphagia dysarthria fatigable chewing proximal muscle weakness Physical exam ice-pack test place ice on the patient's ptosis → ptosis improves login to view 2 more bullets edrophonium chloride (Tensilon test) only used in patients with ptosis or ophthalmoparesis login to view 1 more bullet edrophonium is an acetylcholinesterase inhibitor that has a short duration of action login to view 1 more bullet Imaging Computerized tomography (CT) scan indication to rule out a thymoma view chest Studies Labs serologic testing for autoantibodies anti-AChR login to view 1 more bullet anti-MuSK Electromyogram (EMG) decremental decrease in the compound muscle action potential (CMAP) Differential Lambert-Eaton myasthenic syndrome (LEMS) differentiating factor muscle weakness that improves with use autonomic manifestations Botulism differentiating factor poor or impaired pupillary response to light Thyroid ophthalmopathy Treatment Medical corticosteroids indication login to view 1 more bullet drugs login to view 1 more bullet acetylcholinesterase inhibitors indication login to view 1 more bullet drugs login to view 1 more bullet adverse effects login to view 4 more bullets Procedural intravenous immunoglobulins (IVIg) or plasmapharesis indication login to view 1 more bullet Surgical thymectomy indication login to view 1 more bullet Complications Myasthenic crisis respiratory weakness secondary to myasthenia gravis Prognosis Most patients with ocular involvement progress to generalized myasthenia gravis