Degenerative spine conditions involve the gradual loss of normal structure and function of the spine over time. They are usually caused by aging, but may also be the result of tumors, infections or arthritis. Pressure on the spinal cord and nerve roots caused by degeneration can be caused by:

Slipped or herniated discs 

Spinal stenosis, or narrowing of the spinal canal

Osteoarthritis, or breakdown of the cartilage at the spinal joints