Numbness in both arms may be caused by nerve root cervical spondylosis, spinal cord cervical spondylosis, central nervous system demyelinating disease and other diseases. 1. Nerve root cervical spondylosis: Nerve roots transmit signals from the brain to the limbs, and when they are compressed and stimulated, symptoms such as neck, shoulder and back pain, pain, numbness, and weakness of the upper limbs and fingers may occur. 2. Spinal cord cervical spondylosis: degeneration or herniation of the cervical vertebrae compresses the spinal cord and the blood vessels supplying the spinal cord, resulting in damage to the spinal cord. In the early stage of the disease, there is usually a feeling of heaviness in the lower limbs or difficulty in walking on one or both sides, and with the development of the disease, there will be numbness, pain and weakness in the upper limbs on one or both sides. 3. Demyelinating diseases of the central nervous system: such as multiple sclerosis, optic neuromyelitis optica and other diseases can also appear in both arms numbness and weakness, and can also be accompanied by weakness of the lower limbs or dizziness and other symptoms. The numbness of the arms may be due to other reasons, we should consult a doctor as soon as possible, according to the results of the examination and clinical symptoms of comprehensive diagnosis and treatment.