Right arm weakness is mainly seen in the following cases: 1. myasthenia gravis, if a young or middle-aged patient has right arm weakness, limited lifting, right arm weakness mainly on the right proximal side, with a feeling of light in the morning and heavy in the afternoon or after right arm fatigue arm weakness feeling aggravated, you need to consider that the patient may have myasthenia gravis, you need to go to the hospital to do a head MRI plus CT examination of the thoracic spine to understand whether there is If the patient has hypertension or diabetes mellitus, the patient should be considered to have acute cerebrovascular disease, and a cranial MRI should be done to find out if there is cerebral infarction or bleeding.