Left back paroxysmal numbness caused by arm pain may be related to local cold, exertion and other physiological factors, but also may be related to cervical spondylosis, frozen shoulder and other pathological factors. Physiological factors: due to the back of the neck and shoulder cold or overwork and other factors, easy to cause myofibrillitis, muscle pain, activity is limited, will lead to the left back numbness, arm pain symptoms. Attention to warmth, appropriate rest can be gradually recovered. 2. Cervical spondylosis: mainly caused by cervical degenerative disc, cervical spine hypertrophy and hyperplasia and other factors, can lead to cervical spine osteophytes, disc prolapse, ligament thickening, etc., compression of the cervical spinal cord and nerves, can appear cervical, back and arm pain and numbness symptoms. 3. Frozen shoulder: it is a degenerative and inflammatory disease of the shoulder joint capsule and soft tissues around the shoulder joint. The main symptoms are shoulder joint pain, activity limitation, but also the phenomenon of back numbness, arm pain. Left back paroxysmal numbness caused by arm pain may have other causes, it is recommended to go to the hospital in time, improve the examination to clarify the cause, give targeted treatment or treatment.