Myasthenia gravis is a rare disease. Viets 1 has estimated that the total number of cases in the United States is about 1,500. In spite of this, there is widespread interest in the disease because of the challenge presented with regard to its cause and treatment, because of the complex nature of the pathologic physiology involved and because modern advances in biologic chemistry have afforded a new array of technics for its study. Consequently, there is considerable literature dealing with the condition from groups of investigators with widely differing interests and approaches. CLINICAL FEATURESThe classic clinical picture of myasthenia gravis permits its easy recognition. The undue fatigue of voluntary muscles after exercise, their return to normal or near normal after rest, the absence of muscular atrophy, the mildness of symptoms in the forenoon as compared with the afternoon and evening, the variable clinical course which may be interspersed with spontaneous remissions and relapses and the failure on neurologic examination to demonstrate evidence of structural changes either in the central nervous system or periph¬ eral nerves have enabled physicians accurately to diag¬ nose the disease long before the advent of specific measures for its detection.The muscles most frequently affected are those con¬ cerned with extraocular movements, the involvement of which results in ptosis, strabismus and diplopia in approximately 60 per cent of cases. Then in order of frequency occur generalized weakness, weakness of the extremities, dysarthria, dysphagia, difficulty in masti¬ cation, weakness of the facial muscles and weakness of the muscles of the neck. There may be many variable combinations of muscle group weakness which may show shifting from one set of muscles to another as the disease progresses. Untreated, the disease runs a fatal course in 50 to 75 per cent of cases in a fewyears, but under present methods of therapy the mor¬ tality rate is probably about 10 per cent.1 Death usually results from respiratory paralysis or bronchopneumonia of the aspiration type. DIAGNOSISTo make the diagnosis certain, several highly specific procedures are available. The most satisfactory of these is the intramuscular administration of 1.5 mg.neostigmine methylsulfate with 0.65 mg. atropine sulfate, to prevent gastrointestinal symptoms, accord¬ ing to the plan devised by Viets.2 Recently Tether :; has recommended that the diagnostic test be performed by giving 0.5 mg. of neostigmine intravenously instead of 1.5 mg. intramuscularly. He believes that the intra¬ venous method gives superior results. These tests will result in the abolition of symptoms, or in severe cases their decided amelioration, in from fifteen to thirty minutes by the intramuscular route or in five minutes by the intravenous method. In no other form of muscular asthenia does a response of comparable magnitude occur after the injection of neostigmine. In patients with difficulty in swallowing the correction of the weakness of the pharyngeal muscles by this method c...
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