Numbness of the inner side of the thumb may be related to carpal tunnel syndrome, peripheral neuritis, mental psychological factors and other reasons. 1. Carpal tunnel syndrome: the volume of carpal tunnel decreases due to fracture, wrist sprain, strain injury, etc., and the median nerve squeezes and tendons rub against each other, which leads to numbness of the inner side of the thumb. 2. Peripheral neuritis: If patients suffer from peripheral neuritis due to diabetes, drug intoxication, etc., numbness of hands and feet may occur, and the numbness may include numbness of the inner side of the thumb. 3. Psychological factors: for the existence of anxiety, depression, obsessive-compulsive disorder and other conditions of the patient, may be due to psychological reasons to appear the numbness of the inner side of the thumb. Numbness of the inner side of the thumb may also be related to local injuries, cervical spondylosis, etc. It is recommended that patients should go to a regular hospital for treatment in time to help screen the cause.