Paralysis of the left thumb, index finger and middle finger may be caused by physiological factors, nerve root cervical spondylosis, carpal tunnel, syndrome, diabetes and other factors. 1. Physiological factors: Mechanical compression of the left hand, such as incorrect posture and other local blood circulation disorders, can lead to paralysis of the left thumb, index finger, middle finger, and can improve on its own after lifting the compression, and does not require other treatment. 2. Neurogenic cervical spondylosis: it is related to the strain caused by keeping the head down for a long time, which can lead to the compression of the nerves innervating the upper limbs, which will cause numbness of the left thumb, forefinger and middle finger, and it may be accompanied by the pain and stiffness of the neck, the radiating pain of the upper limbs, and numbness of the upper limbs and other symptoms. 3. Carpal tunnel syndrome: related to chronic strain or acute injury, can lead to compression of the median nerve, which will lead to left thumb, index finger, middle finger paralysis, may also be accompanied by hyperalgesia, muscle atrophy and other symptoms. 4. Diabetes mellitus: Increased blood sugar may lead to peripheral neuropathy, which may lead to paralysis of the fingers of the left hand, and may be accompanied by symptoms such as fatigue, thirst and excessive drinking. The symptoms of paralysis of the left thumb, index finger and middle finger, especially if they are not relieved for a long time, it is recommended to consult a doctor in time to clarify the cause and take treatment under the guidance of the doctor.