Chapter 35 - Spinal stenosis

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Abstract

Narrowing of the spinal canal or foramina is a common finding in spine imaging of the elderly. Only when symptoms of neurogenic claudication and/or cervical myelopathy are present is a spinal stenosis diagnosis made, either of the lumbar spine, cervical spine or both (only very rarely is the thoracic spine involved). Epidemiological data suggest an incidence of 1 case per 100 000 for cervical spine stenosis and 5 cases per 100 000 for lumbar spine stenosis. Cervical myelopathy in patients over 50 years of age is most commonly due to cervical spine stenosis.

Symptomatic spinal narrowing can be congenital, or, more frequently, acquired. The latter may be the result of systemic illneses, namely endocrinopathies (such as Cushing disease or acromegaly), calcium metabolism disorders (including hyporarthyroidism and Paget disease), inflammatory diseases (such as rheumathoid arthritis) and infectious diseases. Physical examination is more often abnormal in cervical spondylotic myeloptahy whereas in lumbar spinal stenosis it is typically normal. Therefore spinal stenosis diagnosis relies on the clinical picture corresponding to conspicuous causative changes identified by imaging techniques, most importantly CT and MRI. Other ancillary diagnostic tests are more likely to be yielding for establishing a differential diagnosis, namely vascular claudication. Most patients have a progressive presentation and are offered non operative management as first treatment strategy. Surgery is indicated for progressive intolerable symptoms or, more rarely, for the neurologically catastrophic initial presentations.

Surgical strategy consists mainly of decompression (depending on the anatomical level and type of narrowing: laminectomy, foraminotomy, discectomy, corporectomy) with additional instrumentation should spinal stability and sagittal balance be at risk.

For cervical spine stenosis the main objective of surgery is to halt disease progression. There is class 1b evidence that surgery is of benefit for lumbar stenosis at least in the short term.

Section snippets

Definition of spinal stenosis

Spinal stenosis refers to the narrowing of the spinal canal causing clinical symptoms secondary to spinal cord or radicular compromise. A distinction must be made between anatomic findings and clinical symptoms, since an anatomically narrow canal is often asymptomatic (Postacchini, 1996). Spinal stenosis can involve the cervical, thoracic (rarely), or lumbar spine, being either monosegmental or multisegmental (adjacent or not), and unilateral or bilateral.

Cervical or thoracic spinal stenosis

History

The first description of a narrowed spinal canal was made by Portal in the early 19th century. Dejerine used the expression “neurogenic claudication” in 1911. This clinical diagnosis was later ascribed to spinal canal stenosis by von Gelderen and Verbiest. Brain identified the clinical picture of cervical spondylotic myelopathy (CSM) in the 1950s, and in the 1970s, Kirkaldy-Willis proposed a physiopathologic frame for the understanding of spinal stenosis development (Kirkaldy-Willis et al., 1978

Classification

Spinal stenosis may be classified according to its etiology or anatomy. The latter refers to either central canal, lateral recess or foraminal stenosis.

Arnoldi considered two types of spinal stenosis from an etiologic point of view: congenital or, more frequently, acquired (Arnoldi et al., 1976).

Congenital stenosis may be idiopathic or may be caused by achondroplasia, being characterized by the presence of short and thick pedicles that render the central canal stenotic in its sagittal diameter

Epidemiology

Lumbar spinal stenosis incidence is fourfold higher than cervical stenosis, amounting to five cases per 100 000 individuals (Johnsson, 1995). Cervical and lumbar stenosis coexist in 5% of patients (Epstein et al., 1984).

Up to 14% of patients seeking specialist care for low back pain have spinal stenosis (Hart et al., 1995).

Cervical spondylotic myelopathy is the most common cause of spinal cord dysfunction in patients older than 50 years (Berhardt et al., 1993).

Some degree of stenosis is present

Narrowing and stenosis

Degenerative disk disease is considered the primum movens of spinal stenosis, being most frequent at the L4–5 level, followed by L3–4, L5–S1, and L1–2 (Epstein, 1998). Kirkaldy-Willis et al., 1974, Kirkaldy-Willis et al., 1978, Kirkaldy-Willis et al., 1982 described the synergistic effects of different degenerative changes causing stenosis of the spinal canal.

Disk degeneration leads to ventral compression by disc protrusion. Loss of disc height is another consequence of degeneration (Fig. 35.1

Diagnosis

The diagnosis of spinal stenosis is based on the patient’s history and is confirmed by imaging studies. The physical examination is often unremarkable in lumbar stenosis (Katz and Harris, 2008). Neurophysiologic studies may be of help to confirm a coexisting pathology or to aid in the differential diagnosis, particularly with polyneuropathies of various causes (Amundsen et al., 1995). The clinical presentation might not be straightforward in the minority of patients with both cervical and

Management

Knowledge of the natural history of the disease is of paramount importance in determining the most appropriate therapeutic course. Since significant spontaneous improvement is unlikely, intolerable symptoms warrant a more aggressive strategy. Progressive disease is to be expected for both cervical and lumbar stenosis, probably more dramatically in the former (Fouyas et al., 2002), therefore the goal of management should be primarily to halt progression. In the case of lumbar stenosis patients,

Outcome

Two randomized trials comparing the efficacy of decompressive laminectomy with that of nonoperative therapy in patients with lumbar spinal stenosis found patients assigned to surgery to have significantly greater improvement in leg and back pain at 1 year and 2 years, although the differences abate with time (Malmivaara et al., 2007, Weinstein, 2008). Two-thirds of patients report to have benefited from the operation (Malmivaara et al., 2007, Weinstein, 2008). Patients with a pronounced

Conclusions

The prevalence of degenerative diseases such as spinal stenosis is likely to increase due to the aging population. The heightened awareness and demand for quality of life will also lead to a future increase in the need for treatment of spinal stenosis.

Until recently there were no clear data to guide conservative versus operative management for this condition. Regarding lumbar spinal stenosis, there is now class 1b evidence that surgery is of benefit in the short term. The best management for

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