One side of the arm numbness causes: First, if it is sudden, clinically considered cerebrovascular disease, seen in ischemic cerebral infarction, transient ischemic attack, also seen in hemorrhagic encephalopathy, the patient appears one side of the arm numbness, accompanied by dizziness, headache, and leg numbness, after the head CT or nuclear magnetic examination, to determine the nature of the lesion and the site; Second, one side of the arm numbness, clinically seen in one side of the arm stuck pressure caused by For example, if one side of the shoulder is compressed by the median nerve, ulnar nerve and radial nerve due to periarthritis, one side of the arm will become numb; third, one side of the arm will become numb due to cervical spondylosis, which is caused by the nerve roots being irritated by the protruding cervical disc.