Original ArticleComparison of Surgeon Rating of Severity of Stenosis Using Magnetic Resonance Imaging, Dural Cross-Sectional Area, and Functional Outcome Scores
Introduction
Magnetic resonance imaging (MRI) is the usual modality used to diagnose lumbar spinal stenosis, but a lack of universally accepted diagnostic criterion or grading systems for lumbar spinal stenosis remains. Schizas et al.1 described a 7-grade classification system based on morphology of the dural sac seen on T2-weighted axial MRI images. A dural cross-sectional area less than 70 mm2 has been previously suggested to represent critical stenosis2 and has been used in multiple studies. In a surgical clinic, such morphometric measurements are unlikely to be used to diagnose and grade spinal stenosis. Surgeons usually rely on visual assessment of axial MRI images to ascertain the degree of stenosis. Despite the central role played by MRI in surgical decision making, there is a paucity of data to indicate a correlation between the severity of stenosis found on MRIs and clinical disability. Many asymptomatic patients have spinal stenosis on MRI.3
Multiple studies4, 5, 6, 7 have failed to establish a correlation between any morphometric grading of stenosis on MRI and clinical disability. None has assessed a correlation between surgeons' visual grading of spinal stenosis on MRI and clinical disability in patients who are evaluated for surgery. This is a critical issue because an operating surgeon's visual assessment of stenosis on MRI has a direct impact on surgical decision making.
Our aim was to assess the relationship of the surgeon's visual grading of spinal stenosis and dural cross-sectional area measurement on MRI, with the patient's disability level using the Oswestry Disability Index (ODI), Visual Analog Scale (VAS), Short Form 36 (SF-36), and symptom severity scale of the Zurich claudication questionnaire.
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Methods
After institutional review board approval, 30 patients who consecutively presented to our academic tertiary-care referral center with symptoms of lumbar spinal stenosis were consented and prospectively enrolled in the study between July 2009 and March 2010. Patients showed a variety of symptoms of lumbar spinal stenosis, including back pain, neurogenic claudication, and leg pain. The symptoms had not been relieved after conservative management for more than 6 weeks. Nonoperative measures that
Results
Sixteen women and 14 men enrolled, with ages ranging between 43 and 86 years (mean, 62.8 years). The mean ODI was 44. We did not find any correlation between the patient's age and ODI score, and VAS scores for back pain or leg pain. We found no correlation between surgeons' grading of stenosis at any level with ODI scores. We found no significant correlation between dural cross-sectional area at any levels and ODI. Table 1 lists overall minimum dural cross-sectional area as well as mean dural
Discussion
Lumbar spinal stenosis associated with neurogenic claudication and clinical disability is the most common indication for spinal surgery.12, 13 Although this is a common diagnosis, there remains a lack of reliable diagnostic criterion and clinical consensus regarding surgical indications. MRI is the choice imaging modality to diagnose lumbar spinal stenosis. A myelogram with computed tomographic myelography can provide a more functional assessment in lumbar spinal stenosis, but surgeons and
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.