Spinal Stenosis
The growth diagnosis of the nineties. It is not more common but there is wider use of imaging to identify it. Spinal stenosis is a catchall term for widely varied anatomic conditions, only a small minority of which have clinical significance. It generally refers to compression of the nerve roots or cauda equina through a narrowing or constriction of the central spinal canal, the lateral recesses or the foramina. Traditionally, it is classified as central, lateral, congenital, acquired or combination.
Back of human figure, spine; Vesling “Syntagma”, 1647.
A study of l00 consecutive patients with symptoms of spinal stenosis referred to a teaching hospital revealed an age range of 15 to 77 (median 59). 95% had LBP in addition to their sciatica. 91% had intermittent claudication -i.e. leg complaints with walking. 70% had sensory disturbances;33% had weakness in the legs; and 12% had symptoms associated with bladder or bowel function. 61% found relief bending forward and 40% experienced pain that was worse walking downhill. The majority had multilevel abnormalities on imaging scans, and 89% had bilateral stenotic changes, though only 42% reported bilateral clinical symptoms. There was no correlation with intensity of pain or number of clinical signs and the imaging (Amundson, l995).
It is theorized that the intermittent neurogenic claudication from spinal stenosis may be due to intermittent compression of the nerve root; another theory is that it is due to nerve root ischemia. A Japanese study (Hayashi et al) suggests that the course of spinal stenosis is relatively stable. The patients don’t necessarily improve overtime, but neither do they deteriorate significantly. In a followup of eight years 18% were better, 20% were worse, and 61% were unchanged symptomatically. The objective findings suggested a poorer picture–16% had improved, 31% unchanged, and 51% worsened.
Onset is gradual, occurring mainly in patients in their fifties and sixties. Walking makes the symptoms worse, while sitting and forward flexion (such as during walking) makes the pain better. The pain may be uni or bilateral below the knees. The pain is frequently non-dermatomal and of a “funny” nature.
Non-specific, but symptoms and neuro signs may be elicited in the office if the patient is allowed to walk for a sufficient amount of time to bring about symptoms.
Evidence of spinal stenosis on imaging scans often has very little relationship with pain and disability. Some suffer no symptoms even though their spinal nerve passages are virtually obliterated, and others have exquisite symptoms with only minor stenotic changes. Likewise, in a Finnish study there was little correlation among post surgical CT findings, symptoms, and disability. This needs to be explained to the patient.
Radiographs may demonstrate osteophytes, degenerative changes at the facet joints, DJD, or degenerative Spondylolisthesis. There is disagreement as to whether CT scanning or the MRI is superior in the diagnosis of spinal stenosis. The main reason is the quality of imaging units vary dramatically, as does the ability to interpret the results. CT myelography has traditionally been the gold standard.
Somatic evoked potentials may be useful in spinal stenosis and in spinal cord myelopathy.
Conservative–epidural steroids may give short term relief (Maximum of two series each year). Aerobic exercise appears to be the best treatment for most patients with symptomatic spinal stenosis, but it is not proven. Exercise improves overall conditioning, aids with weight loss (with potential for biomechanical benefit) and increases endorphins and improves sense of well-being. Regular use of a bicycle can significantly improve walking tolerance. Use of a corset can relieve symptoms during exacerbations.
High failure rate in surgical decompression. Seven to ten year followup after decompress surgery for spinal stenosis indicated that one fourth had undergone a second surgery, one third complained of severe back pain and one half were unable to walk two blocks (Katz,l996).