Patients with numbness and pain in the left shoulder should consider the following reasons: First, cervical spondylosis: When neurogenic cervical spondylosis occurs, the cervical disc will protrude and compress the cervical nerve root, which will mainly manifest as radioactive pain in the neck and one side of the upper limb, which can manifest as numbness in the left shoulder and pain and discomfort in the left shoulder. Secondly, frozen shoulder: When frozen shoulder occurs, there will be pain and abnormal sensation around the shoulder joint, sometimes it will feel numb, sometimes it will feel afraid of cold, and under the stimulation of temperature, especially when the cold invades, it will cause the pain to increase. As the disease progresses, adhesions of the shoulder capsule and limited movement of the shoulder joint will gradually appear.