The main causes of arm and leg numbness are related to brain injury or cerebrovascular lesions, cervical spinal cord injury, prolonged exposure to cold and poor posture. 1. Brain injury or cerebrovascular lesion: For patients with brain injury or patients with cerebral hemorrhage or cerebral infarction, they are prone to central nervous system symptoms, such as hemiplegia, so they will experience numbness in one side of their arms and legs, accompanied by movement disorders. 2. Cervical spinal cord injury: when there is cervical spinal cord injury, it is easy to cause quadriplegia symptoms, so the patient will have numbness in the limbs and trunk, accompanied by the problem of muscle strength decline. 3. Prolonged exposure to cold: If arms and legs are in a cold environment for a long time, it will directly affect the blood circulation, thus producing numbness, and the symptoms will be relieved after appropriate hot compresses. 4. Poor posture: usually maintain an abnormal posture for a long time, arms and legs under pressure, easy to produce local blood circulation phenomenon, which will cause numbness in the arms and legs. If the symptoms are more serious, you need to check the cause of the disease, under the guidance of a professional physician targeted treatment, to prevent later dysfunction.