A prominent feature of many cases of the degenerative spinal disorder is spondylolisthesis. This displacement and malalignment of one vertebral body in relation to the adjacent one may cause little difficulty at first but eventually the patient complains of limitation of motion and pain in the low back radiating into the thighs. In the extreme case examination discloses tenderness near the segment that has “slipped” forward (most often L5, occasionally L4 in middle-aged women) or a palpable “step” of the spinous process forward and shortening of the trunk with protrusion of the lower abdomen (forward shift of L5 on S1, spondyloptosis). Compression of the corresponding spinal roots by the displaced vertebrae causes paresthesia and sensory loss, muscle weakness, and reflex impairment. These neurologic features, however, tend not to be severe. When spondylolisthesis is unstable, meaning the slippage between adjacent vertebrae increases with lumbar flexion or extension, or with standing, new symptoms may appear abruptly in the form of foot drop, urinary retention, or overflow incontinence. The instability is evidenced on conventional radiographs by a change in the diameter of the spinal canal as the patient moves between the flexed and extended position of the back.
A striking syndrome that has been attributed to lumbar stenosis consists of painful legs–moving toes, described by Spillane. There is burning leg pain and continuous and complex rhythmic movements of the toes, as the name implies. Symptoms may begin on one side but become bilateral. Lumbar nerve root compression, most often from stenosis, but sometimes from other types of peripheral damage, underlie most cases.
It is worth comment from our own experience that certain symptoms are sometimes incorrectly attributable to lumbar stenosis; these include imbalance and falling, isolated Romberg sign, and painless progressive foot or leg weakness. Each of these may be embedded in an otherwise typical case of lumbar stenosis but they are more often attributable to other problems such as polyneuropathy or cervical spondylosis.
Surgical treatment of lumbar stenosis Decompression of the spinal canal relieves the symptoms of lumbar stenosis in a large proportion of cases, but the results have been inconsistent. Patients must be chosen carefully for surgery, and success is likely if the clinical features conform to the typical syndrome, mainly pain that altered in various positions and at least partially relieved by rest, with definite evidence of root compression by imaging. In perhaps the most careful trial comparing surgery to conservative treatment for lumbar spinal stenosis, pain and overall function at 2 years was several-fold better in those who had operations (Weinstein et al, 2008). However, interpretation was hampered by a large number of patients who crossed over between arms of the study.
Issues pertaining to the methodology of operation, particularly the need for fusion of the lumbar spine to limit mobility are of interest because of their increased cost over simple decompression but also because patients may query the neurologist about these matters. When there is spondylolisthesis and instability of adjacent segments, current opinion appears to favor fusion in order to reduce worsening spondylolisthesis and back pain. In the absence of slippage and instability, there is evidence from one trial that better patient satisfaction is attained with fusion after the second year compared to simple decompression (Ghogawala et al) but another series has shown little difference before that time. There is also concern about the rates of reoperation at the original level or at adjacent levels, which are destabilized by surgery and subject to spondylolisthesis and restenosis. Some cases of advanced lumbar stenosis have “autofused” adjacent segments may not benefit from the more extensive operation.