Myasthenia gravis is a muscle, or a group of muscles with low tone and excessive relaxation. Skeletal muscles of the whole body can be involved, but it is more common to involve the eye muscles, and the course of the disease is often insidious, with prolonged progression, alternating between remission and recurrence, and gradual progression and aggravation. Myasthenia gravis can be caused by various reasons, such as diseases of the central nervous system, common cerebral infarction, cerebral hemorrhage, brain tumor, which can cause single limb and lateral muscle weakness. Truncal muscle weakness can also occur in spinal cord lesions, and can also be seen in peripheral nervous system diseases, such as peripheral nervous system injuries, such as peroneal nerve palsy, which can cause muscle weakness in the lower limbs. Acute inflammatory demyelinating radiculopathy, also called Guillain-Barré syndrome, can cause bradykinesia of the extremities. There is also myasthenia gravis, myasthenia gravis syndrome caused by paraneoplastic syndromes, as well as low-potassium paralysis, normal-potassium-type paralysis, and high-potassium paralysis, all of which can cause muscle weakness. There are also other neuromuscular pathologies, such as progressive muscular dystrophy, amyotrophic lateral sclerosis, and polymyositis, which can cause symptoms of muscle weakness.