What causes spinal stenosis?

Although rare and only attributed to around 9% of all cases, it is possible to be born with spinal stenosis (this is referred to as congenital, developmental or primary spinal stenosis) and gradually develop associated degenerative symptoms.

More frequently however, degeneration of the spine occurs due to the general wear and tear changes that occur during the aging process. When this results in spinal stenosis, this is referred to as degenerative or secondary spinal stenosis. It has been noted that the condition appears to become problematic most often after a person’s 5th decade (50s) and worsen thereafter.

As a degenerative condition, associated symptoms of stenosis may begin with subtle changes – i.e. a person may begin to gradually decrease levels of physical activity and develop a stooped (bent over) or forward leaning stance (forward flexed posture). Changes such as these may take place gradually, and as such may not even be all that noticeable to a person at first.

Degenerative processes are also a natural part of aging, and as such, changes like a forward flexed posture and decreased activity can easily be associated with that instead of stenosis. Tissues in the spine naturally begin to thicken as we age. Bones also become larger, and together this can begin compressing spinal nerves.

A person with arthritic conditions (which break down cartilage – the cushion-like tissues between bone – and impair the regrowth of bone tissue), such as rheumatoid arthritis and osteoarthritis, can also develop spinal stenosis due to chronic inflammation placing pressure on the spinal cord.

Osteoarthritis can also result in the thickening of ligaments (which bulge into the spinal canal) and bone spurs (overgrowth of bone also known as osteophytes) on the spine, placing increased pressure on the spinal cord and nerves by growing into the spinal canal, and also result in disc changes.

Various other underlying medical conditions or problems can also lead to the onset of stenosis. These include:

• Congenital spinal defects (which often begin to cause stenosis problems between the ages of 30 and 50)
• Scoliosis or spinal curvature
• A spinal cord that is naturally narrow
• Spondylolisthesis, pronounced ‘spon-dl-oh-lis-thee-sis’ (a spinal disorder where a vertebra slips forward onto the bone structures below it)
• Abnormal bone destruction and regrowth / replacement (as happens with Paget’s disease of the bone – bones can become large and brittle, also growing into the spinal canal)
• Achondroplasia (the most common variation of short-limbed dwarfism)
• Herniated discs (the vertebrae’s ‘shock absorbers’ dry out / dehydrate during the natural aging process casing cracks, allowing soft inner tissues to escape and press on spinal nerves)
• Fractures, dislocations and inflammation / swelling of tissue (injury to the spine due to trauma, such as a car accident)
• Bone tumours or growths on the inside of the spinal cord, within the membranes or in the opening between the spinal cord and vertebrae (often identified on an imaging test such as an MRI or CT scan)