Lumbar stenosis can be an immediate or delayed consequence of injury.
With lumbar stenosis, the bony canal that houses the spinal cord in the lower back narrows to the point of impinging on the cord or nerves that arise from it. Although age-related degeneration of the spine is the most common cause of lumbar stenosis, it's not the only cause. Some people are born with narrow spinal canals, but most remain symptom free until something causes further narrowing of this space. Injuries are another possible cause of lumbar stenosis, either due to immediate or long-term effects on the spine.
The hole in the center of a single spinal bone, or vertebra, is called the vertebral foramen. The vertebrae that comprise your spine are stacked and connected by discs and ligaments, with the central holes collectively forming the spinal canal. Your spinal cord and spinal nerves pass through the bony spinal canal. When something causes narrowing at any point in the spinal canal, the spinal cord and nerves are vulnerable to compression. The condition of a narrow spinal canal is called spinal stenosis. "Stenosis" means narrowing and "lumbar" refers to the lower back. Symptoms of lumbar stenosis include pain in the low back that radiates into the buttocks or legs. Numbness and weakness may also develop in the legs.
The bones in your spine are separated by gel-filled cushions called intervertebral discs. Lumbar disc herniations are common injuries, especially among those who do a lot of bending and lifting. When a spinal disc herniates, a portion of its inner contents protrudes outward from the disc. When this protrusion invades the spinal canal, it occupies a portion of the limited space available for the spinal nerves. Pain that radiates from the low back or is associated with leg numbness or weakness often prompts further evaluation with an MRI, which allows the doctor to measure the available space inside the spinal canal at the level of the disc herniation. It also allows the radiologist to see whether the nerves are being displaced or compressed. These are key findings indicative of stenosis.
Degenerative wear and tear affects most aging spines to some degree. Injuries to the spine can accelerate this process. Over time, discs lose moisture and become thin and less resilient. Bone spurs often develop around the joints of the spine. These changes gradually reduce the dimensions of the spinal canal. Degenerative changes are the most common cause of lumbar spinal stenosis. Symptoms of degenerative stenosis are often worse when walking or standing and may be relieved by sitting or bending forward. This is why many elderly people walk with a slight forward bend in their lower backs. Because the condition develops gradually and has a low likelihood of unexpected complications, the North American Spine Society recommends conservative treatment for lumbar spinal stenosis. Your doctor may recommend medication or physical therapy. Surgery to relieve pressure on the spinal cord or nerves may be a consideration for people with moderate to severe symptoms associated with lumbar stenosis.
Fractures, bleeding or swelling may cause stenosis in cases of severe spinal trauma. Thickening of ligaments around the spine can sometimes affect the spinal canal and contribute to stenosis. It is not clear whether changes in the spinal ligaments are a consequence of old injuries or are just part of aging. Additional nontraumatic causes of lumbar spinal stenosis include infection, tumors and cysts. Anything that occupies space and potentially displaces the spinal nerves can cause lumbar spinal stenosis.