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The syndrome of developmental spinal stenosis has been known for some time, but only relatively recently has its treatment become well defined. The most frequent complaint is lower back pain which often radiates into the buttocks or upper thighs and sometimes into the lower extremities in a recognizable mono- or multi-radicular distribution. The pain and sometimes weakness or numbness are typically made worse by prolonged standing or walking. Both the mechanical back exam and the neurological examinations may be entirely normal. Patients suffering from the developmental or "acquired" variety of spinal stenosis usually are in their sixth through eighth decades and the primary cause is osteoarthritis which occurs as a normal part of aging. There are no exercises or diet known at the present time that could prevent or slow the development of this condition.
Many patients remain socially and professionally active well into their sixth, seventh and eighth decades. The development of intractable lower back pain, often ascribed to "old age" may have severe adverse affects on their lifestyle, yet it is entirely treatable. This syndrome, however, is often not recognized, confused with vascular problems or is thought to be due to one of the expected infirmities of old age.
Figure 1
Figure 1 - Schematically depicts the first mechanism of development of neurological deficit in spinal stenosis. Normal lumbar spine (A) and spinal stenosis (B). Notice the presence of osteophyte anteriorly and the infolding of ligamentum flavum which, together with "shingling" of the overgrown laminae, create the "pincer" effect.
Figure 2
Figure 2 - Shows the second mechanism of the development of neurological deficit in spinal stenosis. The normal relationship between the superior facet and the nerve root are seen in A. In B, the arthritic overgrowth of the superior facet compresses the nerve root. (Modified after Ciric et al: J Neurosurg 53:433-443,1980)
The cause of this syndrome is lumbar spinal stenosis and its treatment is entirely surgical. Surgical treatment leads to very satisfactory results in a high percentage of patients with very few complications and the post-surgical recovery is quite rapid in most instances. The pathogenetic mechanism of the neurological symptoms is two-fold and both need to be addressed at surgery. The narrowing of the anteroposterior (front to back) diameter between the vertebral body and the laminae caused by the osteoarthritic "lipping" of the posterior edges of the vertebral body in the form of an osteophyte or bar, combined with the overgrowth of laminae and thickening of the ligamentum flavum, produce a compression syndrome of the cauda equina. The "pincer-like" compression becomes more pronounced in the upright position due to the exaggeration of the lumbar lordosis (natural curve of the spine) or during walking, which accounts for patients developing increased symptoms. The basic distinguishing feature between vascular and neurogenic claudication, which of course may coexist in an individual patient, are the usual absence of back pain at rest or while standing and prompt relief of lower extremities' pain after termination of physical activity in patients with intermittent claudication of vascular origin.
The second mechanism producing the symptoms in spinal stenosis (which may accompany the first or be the sole cause of the complaints) is the compression of individual nerve roots by the overgrown articulating facets as they traverse the neural foramina. Radiculopathy refers to a dysfunction of a nerve root usually due to mechanical compression. In this context it is usually due to a herniated disc or bone spur. Myelopathy refers to compression of the spinal cord.
The diagnosis is confirmed by MRI
and only rarely is computerized tomography and myelography of the
spine required. The radiographic hallmarks are the overgrowth of
articulating facets and narrowing of the anteroposterior diameter
of the spinal canal. The treatment is exclusively surgical; results
are quite satisfactory, even for elderly patients among whom this
syndrome frequently occurs. In most instances the effective treatment
consists of removal of the laminae and overgrown facets, decompressive
laminectomy and foraminotomy often at multiple levels. In only a
small percentage of patient's specifically those that demonstrate
abnormal motion of the spine will require fusion including pedicular
screws and rods. This too is surprisingly well tolerated even in
the very old.
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