Imaging Spinal Stenosis

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


Appl Radiol. 2017;46(1) 

In This Article

Effect on Neural Elements

The effect of spinal canal stenosis may be inferred by directly visualizing the neural structures on high-quality MR images. In the spinal canal, the effect on the spinal cord may be reported descriptively by noting whether the CSF space is merely obliterated, or whether there is deformity of the spinal cord. The presence or absence of abnormal signal in the spinal cord should also be noted. The nerve roots of the cauda equina may also show crowding and redundancy above the site of narrowing (Figure 17). Pfirrmann et al proposed a grading system for disk herniation-related nerve root compromise that showed high correlation with intraoperative findings during subsequent lumbar spine surgery.[17] In the Pfirrmann grading scheme, nerve root compromise is classified into four grades; normal, contact without displacement or compression, displacement, and compression, as shown in Figure 18. Grading of neural foraminal stenosis may be graded by noting effacement of the fat surrounding the nerve roots or by direct observation of nerve root displacement or compression with morphologic change.

Figure 17.

T2-weighted sagittal MR image of L3-L4 spinal stenosis causing crowding and redundancy of the nerve roots within the thecal sac.

Figure 18.

Axial lumbar spine MR images from patients scanned at our institution depict the different grades of nerve root compression based on the Pfirrman classification system.