Myasthenia Gravis (MG) is a chronic autoimmune disorder of neuromuscular transmission resulting in muscle weakness. The term 搈yasthenia?is latin for muscle weakness, and 揼ravis?for grave or serious. Myasthenia gravis is characterized by decremental neuronal response with repetitive nerve stimulation, and evidences itself in a few characteristic, physical ways. The typical symptoms for a myasthenic patient to have a flattened smile and droopy eyes, with slow papillary light responses. The patient may have fixed column deformity, or irregular posture after standing for a short time period. Nasal speech, difficulty chewing and swallowing, dulled facial expression, including difficulty smiling and an ineffective cough due to weak expiratory muscles, difficulty talking, weakness or paralysis that worsens with exertion later in the day, difficulty climbing stairs, difficulty lifting objects, are all also frequently associated with MG.
MG involves fluctuating levels of weakness of commonly used muscles. Weakness occurs when the nerve impulses does not adequately reach the muscle cells which is caused by blockage of the action of neurotransmitters. Acetylcholine Receptors on the muscles are actually destroyed by the immune system, thus it is an immune response of the body against itself. High levels of antibodies block the action of neurotransmitters. The cause of autoimmune disorders such as MG is unknown. In some cases it may be associated with tumors of the thymus. MG affects an estimated 3 out of 10,000 people.
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