Causes of back pain
There are many causes of back pain, the most common of which is a sprain or strain of muscles or ligaments. Muscle spasm can occur after twisting or bending awkwardly, or from a simple sneeze or cough. The majority of muscle spasms tend to get better over time. Severe cases of muscle spasms are treated with medication, physical therapy, or injections.
Disc problems are common causes of back pain. Discs are usually moist, like a sponge with water in it. After a disc injury, or as we age, discs lose water and deteriorate in a process called disc degeneration.
The earliest form of injury to a disc is in the form of tears or fissures in the annulus fibrosis (outer portion) of the disc. The annulus fibrosis is like a large round ligament that prevents the nucleus pulposus (inner portion) of the disc from pushing outward. Tears in the annulus heal by scar formation resulting in tissue that is not as strong as normal tissue. The repeated cycle of many annular tears healing by scar formation lead to a disc that begins to degenerate.
As a disc degenerates it becomes stiff, narrows, and losses it's ability to act as a shock absorber. Bone from the vertebrae above and below the disc may grow forming bone spurs. If bone spurs get large enough, they may cause pressure on nerves in the spinal canal, causing pain, numbness, and weakness in the arms or legs. The combination of disc degeneration and bone spur formation in the spine is called spondylosis. Any narrowing within the spinal canal, from bone spur formation or from any other cause is called spinal stenosis. Spondylosis or spinal stenosis can occur at any level in the spine-cervical, thoracic, or lumbar.
Bulging Disc, Protruding Disc, Herniated Disc, Extruded disc
Over time, because of injury or degeneration, discs start to change shape. Many terms describe this change in shape including bulging, protruding, herniated, prolapsed, slipped. They generally describe a disc that is displaced beyond the limits of the intervertebral disc space.
The earliest change in shape many times is in the form of a disc bulge-a wide based extension of the disc. Often, disc bulges do not cause pain. As the degenerative process progresses, the central, nucleus pulposus portion of the disc can extend through a tear in the outer annular wall of the disc, resulting in a focal protrusion or herniation of the disc. Disc protrusions can cause symptoms of pain, numbness, or weakness from nerve root pinching. In some individuals however, disc protrusions will not cause any symptoms. A disc extrusion is a severe version of a disc protrusion in which a large portion of the nucleus pulposus is displaced through the wall of the disc. A disc extrusion is almost always symptomatic.