Numbness of the left thumb may be caused by cervical spondylosis, carpal tunnel syndrome, angina and other diseases. 1. Cervical spondylosis: numbness of the left thumb may be caused by localized aging of the cervical spine, excessive activity and other reasons leading to local nerve compression, in addition to numbness of the left thumb, there will be numbness in other parts of the hand, dizziness, arm pain and other manifestations. 2. Carpal Tunnel Syndrome: When the patient is overused for a long time, external factors lead to long-term pressure on the wrist, Carpal Tunnel Syndrome may be due to the internal structure of the wrist abnormalities leading to nerve compression in the wrist, which leads to numbness, pain and movement disorders in the thumb or other parts of the hand. 3. Angina pectoris: angina pectoris is a disease of heart dysfunction caused by obstruction of the blood vessels of the heart, and some patients may have numbness in the left arm and the left fingers during the attack. Clinical numbness of the left thumb may also be caused by other diseases, it is recommended to consult a doctor in a timely manner, under the guidance of the doctor for diagnosis and treatment.