Causes of Degenerative Disc Disease
A degenerating spinal disc does not always lead to pain or other symptoms. Because the disc itself has very little innervation, pain usually occurs when the degenerating disc affects other structures in the spine (such as muscles, joint, or nerve roots).

Pain associated with degenerative disc disease generally stems from two main factors:

2. Inflammation. Inflammatory proteins from the disc space interior can leak out as the disc degenerates, causing swelling in the surrounding spinal structures. This inflammation can produce muscle tension, muscle spasms, and local tenderness in the back or neck. If a nerve root becomes inflamed, pain and numbness may radiate into the arm and shoulder (called a cervical radiculopathy in cases of cervical disc degeneration), or into the hips or leg (called a lumbar radiculopathy, in cases of lumbar disc degeneration).

2. Abnormal micro-motion instability. The cushioning and support a disc typically provides decreases as the disc’s outer layer (the annulus fibrosis) degenerates, leading to small, unnatural motions between vertebrae. These micro-motions can cause tension and irritation in the surrounding muscles, joints, and/or nerve roots as the spinal segment becomes progressively more unstable, causing intermittent episodes of more intense pain.

Both inflammation and micro-motion instability can cause lower back or neck muscle spasms. The muscle spasm is the body's attempt to stabilize the spine. Muscle tension and spasms can be quite painful, and are thought to cause the flare-ups of intense pain associated with degenerative disc disease.