In patients with symptoms of lingual muscle atrophy, the diagnosis can be made on the basis of the typical history of the disease and the fact that the affected skeletal muscle is easily fatigued, with a pattern of lightness and heaviness, and improvement after rest or treatment with anticholinesterase drugs. However, for those who only have clinical symptoms but lack objective signs or signs are not typical, further tests should be done to clarify the etiology. 1, muscle fatigue test: make the patient susceptible skeletal muscles continuously repeat a certain action (such as opening and closing the eyes, chewing and swallowing, raising the arm, reaching out and clenching the fist, etc.), the corresponding muscle is easily fatigued after the repeated action, and the symptoms are reduced after rest; 2, drug test: neostigmine methosulfate 0.5 to 1.0 mg subcutaneous injection (atropine 0.5 mg can be injected at the same time to reduce muscarinic side effects). 3, electromyography: repeated electrical stimulation with low-frequency (3Hz) or high-frequency (30-50Hz) stimulation of the ulnar or facial nerve, recording distal evoked potentials, more than 10% attenuation after low-frequency stimulation, no change in high-frequency stimulation or a slight increase, but not more than 50% can be diagnosed, the positive rate of this test is only 70%. Single fiber electromyography is to study the function of nerve and muscle junction by measuring “tremor” with special single fiber needle electrode. 4, MG three kinds of crisis to identify muscle weakness crisis: intravenous injection of Tensilon (1 10mg), the first intravenous injection of 2mg, if there is no adverse reaction, then the remaining 8mg all injected in 30 seconds, in 0.5 ~ 1 minutes after the muscle weakness symptoms significantly improved, 4-5 minutes after the muscle weakness symptoms; if the injection of symptoms temporarily aggravated, muscle tremors, then the cholinergic crisis; if the injection of Tensilon after the symptoms do not change significantly, then the cholinergic crisis. If the symptoms do not change significantly after the injection of Tensilon, the patient is in reactive crisis.