Changes to the size or shape of the spinal canal usually occur as a result of aging. Normally, there is enough space in the openings of the spinal bones to accommodate the nerve fibres branching off the spinal cord; however, when the size of these openings is reduced (due to an overgrowth of bone or adjacent tissue) nerve compression can occur.
Structures adjacent to the spinal column can also be affected in the following ways:
- Spinal ligaments can thicken and harden
- Bones and joints (often affected by osteoarthritis) can enlarge; bone spurs can develop
- Discs can bulge or collapse
- Vertebrae may slip out of place
There are two types of spinal stenosis: lumbar stenosis and cervical stenosis. While lumbar spinal stenosis is more common, cervical spinal stenosis is often more dangerous because it involves compression of the spinal cord, as explained below in more detail.
Many people older than age 50 have some narrowing of the spinal canal (spinal stenosis) but do not have symptoms. If the nerve roots or spinal cord become squeezed, symptoms may include:
Numbness, weakness, cramping, or pain in the legs, feet, or buttocks. These symptoms get worse when you stretch or extend your back, such as when you walk (especially downhill), stand straight, or lean backwards. The pain gets better when you flex your spine forward, such as when you sit down, lean over a grocery cart, or walk uphill. The other symptoms can include:
- Stiffness in legs and thighs.
- Low back pain.
- In severe cases, loss of bladder and bowel control
Surgery for lumbar spinal stenosis should only be considered if a patient’s ability to participate in everyday activities is unacceptably reduced and a concerted effort to relieve symptoms through non operative means has been unproductive. The surgical treatments include lumbar laminectomy, with/without fusion.
- Lumbar laminectomy: Lumbar laminectomy is a surgical procedure to relieve pressure on the spinal nerves. A laminectomy involves removing a section of the bony covering over the back of the spinal canal. This takes pressure off the spinal nerves.
Surgical Procedure. The surgeon makes a short incision down the middle of the low back. In a complete laminectomy, the spinous process (the bony projection off the back of the vertebra) and the lamina on each side are removed over the area where stenosis is occurring. To accomplish this, the surgeon cuts along the inside edge of the facet joint on each side and detach the lamina bone completely from the pedicle bones. This also opens a section in the bony ring. A small portion of the ligamentum flavum is also removed. The muscles and soft tissues are put back in place, and the skin is stitched together
- Posterior Lumbar Fusion: A posterior lumbar fusion may be needed after a surgeon performs a lumbar laminectomy. The fusion procedure is recommended when a spinal segment has become loose or unstable. A fusion surgery joins two or more bones into one solid bone. This keeps the bones and joints from moving. In this procedure, the surgeon lays small grafts of bone over the back of the spine. Most surgeons also apply metal plates and screws to prevent the two vertebrae from moving.