Management of Lumbar Spinal Canal Stenosis

Abstract

BACKGROUND Spinal stenosis is one of the most common conditions in the elderly. It is defined as a narrowing of the spinal canal. The term stenosis is derived from the Greek word for narrow, which is "Stenos". The first description of this condition is attributed to Antoine portal in 1803. Verbiest is credited with coining the term spinal stenosis and the associated narrowing of the spinal canal as its potential cause. [1-10] Kirkaldy-Willis subsequently described the degenerative cascade in the lumbar spine as the cause for the altered anatomy and pathophysiology in spinal stenosis. [11-15] If compression does not occur, the canal should be described as narrow but not stenotic. Some studies defined lumbar spinal stenosis as a "narrowing of the osteoligamentous vertebral canal and/or the intervertebral foramina causing compression of the thecal sac and/or the caudal nerve roots; at a single vertebral level, narrowing may affect the whole canal or part of it" (Postacchini 1983). This definition distinguished between disc herniation and stenosis. [16]. The most common type of spinal stenosis is caused by degenerative arthritis of the spine. Hypertrophy and ossification of the posterior longitudinal ligament which usually are confined to the cervical spine, and diffuse idiopathic skeletal hyperostosis (DISH) syndrome also may result in an acquired form of spinal stenosis. Congenital forms caused by disorders such as achondroplasia and dysplastic spondylolisthesis are much less common. Congenital spinal stenosis usually is central and is evident or imaging studies. Idiopathic congenital narrowing usually involves the anteroposterior dimension of the canal secondary to short pedicles; the patient otherwise is normal. In contrast, in achondroplasia, the canal is narrowed in the anteroposterior plane owing to shortened pedicles and in lateral dimension because of diminished interpedicular distance. Acquired forms of spinal stenosis usually are degenerative. This process is most commonly localised to the facet joints and ligamentum flavum, with the resultant arthritic changes in the joints visible on radiographic studies. Frequently, these abnormalities are symmetrical and bilateral. The L4-L5 level is the most commonly involved, followed by L5-S1 and L3-L4 disc herniation and spondylolisthesis may exacerbate the narrowing further.