What is Spinal Stenosis?
Spinal stenosis is the narrowing of your spinal canal and nerve root canal along with the enlargement of your facet joints. Most commonly it is caused by osteoarthritis and your body’s natural aging process, but it can also develop from injury or previous surgery. As the spinal canal narrows, there is less room for your nerves to branch out and move freely. As a result, they may become swollen and inflamed, which can cause pain, cramping, numbness or weakness in your legs, back, neck, or arms. Spinal stenosis is a degenerative condition that happens gradually over time and refers to:
- Narrowing of the spinal and nerve root canals
- Enlargement of the facet joints
- Stiffening of the ligaments
- Overgrowth of bone and bone spurs
Stenosis can occur along any area of the spine (cervical, thoracic, lumbar), but is most common in the lumbar area. Nearly every adult’s spinal canal narrows with age; however, for most people this does not cause symptoms. Narrowing of the nerve root canal (lateral stenosis) presses on the spinal nerves, causing inflammation and pain. Narrowing of the spinal canal (central stenosis) presses on the spinal cord causing inflammation and weakness.
Anatomy of the Spinal Canal
To understand spinal stenosis, it is helpful to understand how your spine works. Your spine is made of 24 moveable bones called vertebrae. The vertebrae are separated by discs, which act as shock absorbers preventing the vertebrae from rubbing together. Down the middle of each vertebra is a hollow space called the spinal canal that contains the spinal cord, spinal nerves, ligaments, fat, and blood vessels. Spinal nerves exit the spinal canal through the intervertebral foramen (also called the nerve root canal) to branch out to your body. Both the spinal and nerve root canals are surrounded by bone and ligaments. Bony changes can narrow the canals and restrict the spinal cord or nerves.