There are many patients who go to the clinic for back pain, and after examining MRI and CT, they often get the diagnosis of “lumbar disc bulge” or “lumbar disc herniation”. For this reason, they feel panic and worry that their disease is very serious, but in fact this is only an imaging diagnosis, not a clinical diagnosis. The imaging diagnosis is not necessarily the presence of “disease”, but the imaging manifestations that cause the disease. In layman’s terms, this means having some basis for the onset of the disease, but not necessarily having the disease. The lumbar disc bulge is different from the lumbar disc herniation, which is a manifestation of degenerative changes in the lumbar spine, and the lumbar disc herniation is not necessarily a disease, but only when the lumbar disc herniation compresses the nerve and causes pain or sensory-motor disorders in the corresponding segment, then it is called “disease that is lumbar disc herniation”. You should note that I have added the word “disease” after lumbar disc herniation here. If there is a herniated disc without symptoms, it is not called a “disease” until the nerve is compressed and the corresponding symptoms appear. Note also that I used the word “corresponding” again, which means that the symptoms caused by the compressed nerve must be the symptoms of the compressed nerve. For example, if a herniated disc compresses L4 and the pain manifests in the L3 innervation zone, the diagnosis cannot be established. The diagnosis can only be established if the symptoms are manifested in the L4 innervation zone. Therefore, I hope that you will not only look at the imaging report to make your own diagnosis, but also rely on the clinician’s diagnosis. Next I would like to introduce the physiological and pathological basis of “lumbar disc bulge” for better understanding. The intervertebral disc is the basis of spinal motion, and it completes the movement of the spine with the two posterior synovial joints. The intervertebral disc is the hub linking the vertebral bodies. The lower part of the upper vertebral body and the upper part of the lower vertebral body are dense and form a dense bone plate called the end plate, which forms the upper and lower ends of the intervertebral disc respectively. The structure between the two end plates is called the intervertebral disc, which is surrounded by a strong fibrous ring, shaped like a car tire, attached to the end plates above and below. The fibrous ring occupies almost one-half of the outer radius of the intervertebral disc. The middle part is the nucleus pulposus, which is jelly-like and is enclosed in a confined cavity formed by the annulus fibrosus and the upper and lower end plates. The function of the intervertebral disc is to carry pressure, which is transmitted from the lower endplate of the upper vertebra to the upper endplate of the next vertebra. The intervertebral disc can be compared to the human body’s “shock absorption system”. As we age, the function of various organs or systems in the body decreases, and the degeneration of the intervertebral disc is the basis of spinal degeneration and the initiating factor of spinal degeneration. Degeneration is manifested by loss of water in the nucleus pulposus and relaxation of the fibrous ring structure with aging, and this change is uniform and consistent, making the intervertebral space narrower. As a result, the nucleus pulposus signal decreases on MRI, the annulus fibrosus relaxes and bulges out to the periphery, the intervertebral height decreases on CT and X-ray, the disc bulges out uniformly to the periphery, and osteophytic changes occur over time. In conclusion, bulging discs are a manifestation of spinal degeneration and cannot be diagnosed as a disease.