Spinal stenosis is a narrowing of the open spaces within your spine. This narrowing can put pressure on your spinal cord and the nerves that travel through the spine. Spinal stenosis occurs most often in the neck and lower back. While some people have no signs or symptoms, spinal stenosis can cause pain, numbness, muscle weakness, and problems with bladder or bowel function. Spinal stenosis is most commonly caused by wear-and-tear changes in the spine related to aging.