There are three causes of left hand numbness in girls: first, it may be localized compression or lesion of peripheral nerves, such as median nerve, ulnar nerve, radial nerve, etc., which leads to numbness of the left hand. This time you need to find the cause of the disease and give vitamin B to treat it. Second, there may be cervical spondylosis, cervical spondylosis can lead to disc protrusion and nerve root compression, resulting in numbness of the left hand, left hand numbness caused by this disease is often accompanied by upper limb pain and other clinical manifestations. Third, there may be brain diseases, suffering from some cerebrovascular diseases, such as cerebral thrombosis, may also lead to numbness of the limbs. If this is suspected, the patient needs to go to the hospital for cranial MRI examination, it is best to observe for a day, appropriate activities, to see if the symptoms can be reduced.