Imaging Spinal Stenosis

Kiran S. Talekar, MD; Mougnyan Cox, MD; Elana Smith, MD; Adam E. Flanders, MD

Disclosures

Appl Radiol. 2017;46(1) 

In This Article

Quantitative Diagnostic Criteria

In 2011, Steurer and associates conducted a review of quantitative radiologic criteria published in the literature, and compiled a list of descriptive terms for lumbar stenosis.[7] The quantitative diagnostic criteria for spinal canal stenosis are less widely accepted,[8] and only the mostrelevant are discussed in this article. For the evaluation of the spinal canal, stenosis is compatible with an AP diameter of the canal less than 10 mm in the cervical spine or 12 mm in the lumbar spine (Figure 19). On MR images, a mid-sagittal diameter of the dural sac less than 10 mm is also consistent with stenosis (Figure 19). Separate evaluation of the dural sac diameter is useful in cases where there is normal bony canal diameter on non-contrast CT images, for example epidural lipomatosis causes mass effect on the dural sac with normal spinal canal diameters. Additional imaging criteria such as cross-sectional area of the dural sac and transverse diameter of the osseous spinal canal are also published in the literature.[7]

Figure 19.

(A) Noncontrast axial CT of the lumbar spine showing typical measurements obtained in the AP diameter for evaluation of stenosis. Measurements may also be obtained in the sagittal plane (B).

For evaluation of the neuroforamen, an anteroposterior diameter of the foramen of less than 3mm on sagittal images is considered diagnostic for stenosis (Figure 20A). A lateral recess height less than 3mm or lateral recess angle less than 30 degrees is also further evidence of spinal stenosis (Figure 20B).[7]

Figure 20.

(A) Sagittal T2-weighted image of the lumbar spine with typical measurement of the neural foraminal diameter. (B) Axial T2-weighted image of the lumbar spine that shows sample measurements of the lateral recess height and lateral recess angle.

The joint forces in the revised lumbar spine nomenclature recommendations[6] suggest that spinal canal stenosis can be graded as mild, moderate, or severe if the canal is narrowed by less than a third, one-third to two-thirds, or greater than two-thirds of the original diameter, respectively. A similar grading system can be employed for the neural foramen.

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