If a patient experiences pain like pins and needles in the left arm, it is possible that a fracture of the ulnar radius has occurred after a traumatic injury to the left forearm. In this case, the patient should consult a doctor promptly, who will be able to make a clear diagnosis by taking an X-ray of the left ulnar radius after examination, and then take different treatments according to the specific circumstances of the fracture. In addition, if the patient has cervical spondylosis, the spinal cord is compressed and the nerve roots on the left side are stimulated, which also leads to pins and needles pain in the left arm, along with localized loss of skin sensation and loss of muscle strength. An MRI of the cervical spine can be taken to make a clear diagnosis. In the treatment, the patient can take conservative treatment, instruct the patient to rest in bed, take a neck brace or collar to fix the neck, and apply neurotrophic drugs, such as oral mecobal and methylcobalamin tablets, to relieve clinical symptoms.