Spinal stenosis means spinal narrowing. It invariably occurs due to longstanding wear and tear in the affected part of the spine and can happen either in the neck or the lower back. Most commonly, however, spinal stenosis is used to refer to problems in the lumbar spine or lower back.
There are a variety of changes that occur in parts of the spine to lead to spinal stenosis. The first of these is enlargement of the small joint at the back of the spine (the facet joints). As with any joint affected by arthritis in the body, there can be enlargement of the affected joint. If this occurs to the facet joints, it can gradually encroach on the spinal canal through which the nerves are running. There can, in response to wear and tear, also be a thickening of the ligaments surrounding the spinal canal. These ligaments can also buckle and this can further compromise the calibre of the spinal canal. Finally, there can be a diffuse bulging of the disc capsule (annulus) or a more discrete disc prolapse (hyperlink) which can further contribute to the spinal canal narrowing.
Due to the gradual development of spinal stenosis, symptoms often do not present in a sudden or dramatic way as they do with the sciatica of an acute disc prolapse. The characteristic symptom that can result from spinal stenosis is claudication. This symptom results not from direct physical compression of the nerves but rather that the confined space within the spinal canal means they cannot get enough blood and oxygen when they are being used. The nerves being starved of blood is the problem underlying claudication.
Claudication consists of symptoms in the legs which are brought on by exertion. With exertion the nerves require more blood and oxygen which they simply cannot get. Some people describe claudication as an aching within the legs, to other people it feels more like numbness. It is sometimes described as though one’s legs simply are not doing as they are told and they can become weak and unreliable. For some people, with relatively mild spinal stenosis, claudication will only come on after walking for a long distance or standing for long periods. For other people, it can be very short distances or almost immediately on standing. It is characteristically relieved by resting and so most people will sit down to help their claudication.
The main alternative explanation for claudication symptoms in your legs is the lack of blood supply to the muscles themselves in the legs. This can happen if there is a narrowing of the arteries in the legs. If you are investigated for claudication but no spinal stenosis is found, it is very likely that you will be referred on for assessment of the blood vessels in your legs.
For many people, the symptoms of spinal stenosis remain manageable and they simply modify their physical activities accordingly. However, if the claudication symptoms become intrusive, surgery can be a very good option to consider.