Drug experimental diagnosis Neostigmine 1.5mg intramuscularly can improve symptoms within 10-30min for 4h. If the response is still uncertain, a long-term trial with oral anticholinesterase drugs for several weeks is possible. The ocular muscle type is the least sensitive to this drug, so it is difficult to make a diagnosis in cases of myasthenia gravis that are limited to the ocular muscle. In patients taking anticholinesterase drugs, it is important to avoid symptoms of increased cholinergic muscle weakness and to be prepared to deal with allergic reactions and respiratory complications when performing this test. Tensilon causes mild headache, febrile sensation, nicotinic acid can repeat certain symptoms, but does not affect neuromuscular conduction, so it is a more ideal control drug. 1, electrophysiological examination of the muscle in patients with myasthenia gravis shows a decrease in the amplitude of the tiny end-plate potential, causing an abnormal decrement of the activity potential. Domestic use of low-frequency repetitive electrical stimulation, this method has diagnostic significance, the advantage is simple, but not very sensitive, especially in the early onset, about 50% of patients with myasthenia gravis does not change this examination. A more sensitive method to check neuromuscular conduction is single fiber electromyography. A single fiber needle electrode is inserted between two muscle fibers innervated by the same motor nerve. This test can be used to monitor the clinical course of myasthenia gravis. It has the advantage of being more sensitive and allowing an early diagnosis, but requires the use of expensive equipment and neurophysiological evaluation. Stapedial reflex attenuation is also used to diagnose myasthenia gravis and is highly sensitive to the oculomotor type, but responds poorly to the generalized type. 2. Serological tests Levels of acetylcholine receptor antibodies (radioimmunoassay) Serum acetylcholine receptor antibodies are highly specific for myasthenia gravis and can be measured in 90% of cases. This antibody level is generally considered to be independent of the patient’s clinical symptoms, but patients with the simple eye type tend to have lower antibody titers. The enzyme-linked immunosorbent assay (ELISA) measures antibodies with a higher sensitivity than the radioimmunoassay. Studies have demonstrated that the degree of muscle weakness in patients with myasthenia gravis is closely correlated with the relative titer of acetylcholine receptor antibodies in their serum. In addition, serum immunoglobulin tests, including IgG, IgA, IgM, C3, complement assay and other immunological tests can be performed, all of which are helpful in the diagnosis of myasthenia gravis. The serum of patients with myasthenia gravis contains many non-specific antibodies, including anti-transverse muscle, anti-nuclear, anti-thyroid, anti-gastric wall, anti-sperm production and anti-neuronal antibodies, which can be measured for diagnostic reference. 3.Chest X-ray is a relatively simple examination method, and it can diagnose up to 62% of combined thymoma. The diagnosis of thymoma can be made in 62% of the cases. Mediastinal radiography can detect thymoma in 30% of the cases with negative chest radiographs. CT scan can identify cystic or solid, calcified or not, and can detect small thymoma, and can also indicate malignant thymoma such as invasion of pleura, lung and large blood vessels.