There are two main causes of pain on the left side of the body: the first is the problem of the central brain, caused by serious cerebral thrombosis and insufficient blood supply to the brain. The second point is caused by cervical spondylosis, more commonly caused by serious cervical spine hyperplasia, bone spurs or cervical disc herniation that affects the nerve compression, causing numbness and pain in the left arm, back and chest, etc. Pain can occur. Clinically, there may also be other causes, which require a hospital examination, mainly cervical spine MRI, head MRI and blood tests, such as routine blood tests and biochemical tests, to rule out the possibility of malignant tumors or systemic diseases.