The cause of numbness in the big finger, i.e. the thumb, may be due to stroke, carpal tunnel syndrome, cervical spondylosis, diabetes, etc. It may also be caused by over-exertion of the hand or exposure to cold. Some lesions of the central nervous system may lead to numbness of the thumb, such as acute cerebral infarction, stroke, multiple sclerosis, spondylitis, and so on. In addition to numbness of the thumb, there are often hemiplegia, slurred speech, choking on drinking water, impaired consciousness and other symptoms. Carpal tunnel syndrome and cervical spondylosis may compress the median nerve and cervical nerve roots, thus leading to numbness in the thumb. Diabetic peripheral neuropathy, Guillain-Barré syndrome, and drug toxicity can cause both damage and lesions to the peripheral nerves, which may also cause numbness in the thumb. There are some physiological causes that may also lead to numbness in the thumb. For example: prolonged exertion of the thumb, pressure, in a cold environment, or hypoxia and ischemia of the hand, usually after these influencing factors are lifted, numbness symptoms can be relieved. Thumb numbness symptoms, especially for a long time or progressive aggravation of the person is recommended to consult a doctor in a timely manner, to identify the causes, targeted treatment.