The following causes are common for weak legs, weakness and inability to stand: First, more severe spinal cord type cervical spondylosis, or congenital cervical spinal stenosis. Patients will show symptoms of weakness in both lower extremities and a feeling of stepping on cotton when walking. MRI can reveal that the spinal nerves are severely compressed and even degenerated and necrotic. Surgery should be performed in time to release the nerve compression and restore the weight-bearing function of both lower limbs. Second, the patient has severe intracranial lesions, such as cerebral ischemic attack, cerebral embolism, and cerebral thrombosis, which can also lead to loss of innervation of the leg muscles, producing disuse atrophy and inability to stand and walk. Patients usually have intracranial clinical symptoms such as headache, nausea, vomiting, loss of vision, hearing loss, and even language skills may be affected to some extent, which should also be treated promptly.