Stenosis means narrowing or being narrow, and is used mostly to indicate restriction of fluid movement in the circulatory, excretory and digestive tracts.
The structure which is narrowed may be so due to illness, disease or congenital factors.
What is spinal stenosis?
Spinal stenosis is a condition which occurs mostly in older people, 60 years plus. It is a collection of symptoms caused by a narrowing of the canal in the backbone which carries the spinal (nerve) cord. It is an important consequence of lumbar spinal degenerative changes, and in the USA 0.1% of people over 65 years old undergo spinal operation for this problem yearly.
Diagnosis of spinal stenosis
Any elderly person presenting with buttock and leg pain should raise the question of the diagnosis of spinal stenosis. Patients typically complain of buttock or leg pain on standing and/or walking and which is relieved by sitting or bending. There may be pain from disc and facet joint changes in the lumbar spine also. On examination there are no findings which are diagnostic of this condition.
Xrays of the lumbar spine usually show advanced degenerative changes in the lower lumbar segments. These include narrowing of the disc segments.
The spinal canal
This is the tunnel formed in the vertebral column (backbone) by the lining up of all the central canals of each vertebral bone. The canal extends from the head down to the sacrum and carries the spinal cord and its offshoots, the spinal nerves.
Most of the time there is enough room in the spinal canal and the nerve cord and nerve roots have space. Difficulties arise if there is not enough room for nerve structures to function normally.
The importance of the size of the spinal canal
A narrow spinal canal is something that many people have quite normally. However, having a spinal canal of less than average size makes a person more likely to suffer from back pain or disc protrusion problems, and may influence the degree of recovery from disc surgery.
The shape of the spinal canal
The shape of the canal is important in determining whether someone gets stenosis or other types of back pain problems. The shape varies in different parts of the spine.
It tends to be oval in the upper lumbar spine, changing to a more triangular shape in the lower lumbar spine. Some people have a more trefoil-like shape in the lower lumbar spine, which is more vulnerable to the changes which occur in stenosis.
The boundaries of the spinal canal are made up of bone, the disc, the facet joints and ligaments.
What changes when spinal stenosis develops?
Changes occur in the spine with age and are often of no significance. However, the structures which surround the spinal canal can change in a way that cuts down the space available in the canal for the nerves.