Myasthenia gravis

Learning objectives

Myasthenia Gravis (MG) is an autoimmune disease of the neuromuscular junction at the postsynaptic membrane
Autoantibodies to AchR disrupt its function by receptor blockade and conformational change leading to increased degradation which results in decreased motor end-plate potential amplitude and failure in the initiation of muscle contraction
It is the most common disorder of the neuromuscular junction

Extraocular muscle group	Ptosis Diplopia
Bulbar muscle group	Dysarthria Dysphagia Dysphonia
Axial-limb muscle group	Symmetrical, more often in proximal muscles
Respiratory muscles	Dyspnea

Symptoms vary over the day and from day to day, often with normal or near-normal muscle strength in the morning
Clinical presentation varies from mild and localized to severe, generalized weakness of multiple muscle groups

Myasthenic crisis is a life-threatening condition in which severe respiratory muscle insufficiency leads to respiratory failure

Antibiotics	Aminoglycoside Fluoroquinolones Tetracycline Macrolides Sulfonamides Penicillin Vancomycin Clindamycin Ketolides
Non-depolarizing neuromuscular-blocking agents	Pancuronium Vecuronium Atracurium
Cardiovascular agents	Beta-blockers Calcium channel blockers Procainamide Quinidine Beryllium
Anesthetic agents	Local: procaine, lidocaine, bupivacaine Inhalation: halothane, isoflurane Neuromuscular blockers
Anticonvulsants	Carbamazepine Gabapentine Phenobarbital Phenytoin Ethosuximide
Other agents	Botulinum toxin Chloroquine Hydroxychloroquine Magnesium Penicillamine Quinine Iodinated contrast agents Cisplatinum Riluzole Interferon-alfa Interleukin-2

Treatment

Myasthenia gravis, myasthenic crises, anticholinesterase agents, immunoglobuline, glucocorticoids, plasma exchange