As the ligaments of the spinal column become stiff and thicker with age, more narrowing occurs which may cause impingement on the nerve roots and spinal cord. Stenosis may occur in the central spinal canal (central stenosis) where the spinal cord and the cauda equina are located. The lateral foramen or openings are where the individual nerve roots exit out to the body. When they are compressed outside of the foramen, this is called Lateral stenosis and is the most common form of Lumbar stenosis.
Another form of stenosis is termed foraminal stenosis and is the result of nerve roots getting caught or compressed within the spinal canal. Herniated discs or bony protrusions are the most common reasons in these cases. Size and age of the spinal canal determine the severity of the stenosis.
Spinal stenosis may be caused by a number of diseases, injuries, or conditions. Age, degenerative causes such as osteoarthritis, and bony processes are the most common, but some people are born with a smaller spinal canal than normal and this is called Congenital Stenosis. Rare conditions such as tumours, abscesses, spinal curvature, and metabolic syndromes can result in spinal stenosis.