Neurology India, Vol. 59, No. 3, May-June, 2011, pp. 473-474
Letter to Editor
Management of focal lumbar canal stenosis: Importance of upright dynamic radiographs
Manish K Kasliwal, Harel Deutsch
Department of Neurosurgery, RUSH University Medical Center, Chicago, IL, USA
Correspondence Address: Manish K Kasliwal Department of Neurosurgery, RUSH University Medical Center, Chicago, IL USA firstname.lastname@example.org
Date of Submission: 16-Feb-2011
Code Number: ni11137
Magnetic resonance imaging (MRI) has become an important and not uncommonly the sole investigation for the diagnosis and management of lumbar canal stenosis with a decreasing role of plain radiographs in the initial workup. However, MRI of the spine performed in a supine position may not often detect the presence of listhesis in cases of focal lumbar canal stenosis, and physicians should consider and not underscore the role of dynamic radiographs which may unravel an underlying listhesis before embarking on surgical management of lumbar canal stenosis. ,
A 57-year-old lady presented with complaints of low back pain and numbness involving bilateral lower limbs of 3-year duration. She was treated conservatively, but continued to have persistent symptoms. MRI of the lumbar spine revealed the presence of focal lumbar canal stenosis at the L4/5 level and a possibility of minimally invasive laminectomy was considered [Figure - 1]. Axial MRI showed the presence of severe canal stenosis with no evidence of facet joint hyperintensity. We however routinely obtain dynamic upright X-rays for such patients before surgery which revealed the presence of grade I degenerative spondylolisthesis [Figure - 2]. In view of the presence of listhesis, a decompression with instrumentation and fusion was performed. The patient had an excellent outcome after the surgery.
MRI has become the investigative modality of choice for diagnosis of neural compression in degenerative diseases of the spine. Dynamic translational instability may be a significant contributor for patients' symptoms and often requires surgery more extensive than simple decompression. , Though MRI may show the presence of obvious slip, grade I/II slip quite typical of degenerative spondylolisthesis may not be apparent on a supine MRI. The recognition of hyperintensity in the facet joints on axial MRI has been shown to be a harbinger of a coexistent spondylolisthesis and various authors recommend weight-bearing dynamic radiographs to detect the presence of listhesis in the presence of facet joint hyperintensity. , Though this is useful, it may not be true always as we had seen in our practice and an instability may coexist with a focal lumbar canal stenosis in the absence of facet joint hyperintensity as was seen in the case described. The presence of a focal stenosis itself may indicate an underlying instability due to the tendency of the spine to maintain the normal spine alignment leading to hypertrophy of the ligaments secondarily resulting in focal lumbar canal stenosis. An upright dynamic X-ray of the lumbar spine should be considered for all patients with focal lumbar canal stenosis to rule out the presence of spondylolisthesis and facilitate selection of appropriate surgical treatment.
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