Korean J Radiol.  2012 Aug;13(4):403-411. 10.3348/kjr.2012.13.4.403.

Differentiation between Symptomatic and Asymptomatic Extraforaminal Stenosis in Lumbosacral Transitional Vertebra: Role of Three-Dimensional Magnetic Resonance Lumbosacral Radiculography

• Byun WM
• Kim JW
• Lee JK

• KMID: 1383851
• DOI: http://doi.org/10.3348/kjr.2012.13.4.403

Abstract

OBJECTIVE
To investigate the role of lumbosacral radiculography using 3-dimentional (3D) magnetic resonance (MR) rendering for diagnostic information of symptomatic extraforaminal stenosis in lumbosacral transitional vertebra.
MATERIALS AND METHODS
The study population consisted of 18 patients with symptomatic (n = 10) and asymptomatic extraforaminal stenosis (n = 8) in lumbosacral transitional vertebra. Each patient underwent 3D coronal fast-field echo sequences with selective water excitation using the principles of the selective excitation technique (Proset imaging). Morphologic changes of the L5 nerve roots at the symptomatic and asymptomatic extraforaminal stenosis were evaluated on 3D MR rendered images of the lumbosacral spine.
RESULTS
Ten cases with symptomatic extraforaminal stenosis showed hyperplasia and degenerative osteophytes of the sacral ala and/or osteophytes at the lateral margin of the L5 body. On 3D MR lumbosacral radiculography, indentation of the L5 nerve roots was found in two cases, while swelling of the nerve roots was seen in eight cases at the exiting nerve root. Eight cases with asymptomatic extraforaminal stenosis showed hyperplasia and degenerative osteophytes of the sacral ala and/or osteophytes at the lateral margin of the L5 body. Based on 3D MR lumbosacral radiculography, indentation or swelling of the L5 nerve roots was not found in any cases with asymptomatic extraforaminal stenosis.
CONCLUSION
Results from 3D MR lumbosacral radiculography Indicate the indentation or swelling of the L5 nerve root in symptomatic extraforaminal stenosis. Based on these findings, 3D MR radiculography may be helpful in the diagnosis of the symptomatic extraforaminal stenosis with lumbosacral transitional vertebra.

Keyword

Extraforaminal stenosis; MRI; Spinal nerve root

MeSH Terms

Aged
Aged, 80 and over
Contrast Media/diagnostic use
Diagnosis, Differential
Female
Humans
Imaging, Three-Dimensional
Lumbosacral Region/*pathology
Magnetic Resonance Imaging/*methods
Male
Middle Aged
Nerve Compression Syndromes/*diagnosis/pathology
Osteophyte/pathology
Spinal Stenosis/*diagnosis/pathology

Figure

• 

  Fig. 1 L5 nerve root measurement by 3-dimensional magnetic resonance (3D MR) lumbosacral radiculography and axial Proset multi-planar reconstruction (MPR) images. On 3D MR radiculography (A), proximal nerve segment between thecal sac and dorsal root ganglion (DRG) is defined as traversing nerve root (arrow). Spindle-shaped nerve root in extraforaminal or foraminal zones is defined as DRG (blanked arrow), and nerve root in extraforaminal zone beyond DRG is defined as exiting nerve root (long arrow). Tilting angle of nerve root is measured using parallel line to thecal sac (black arrow) and another line (double arrows) passing through center of nerve root and spinal nerve and parallel to its long axis. On axial Proset MPR images (B) for measurement of right L5 nerve root width, diameters of exiting nerve root (small arrow), DRG (thick arrow), and traversing nerve root (long arrow) are measured.

• 

  Fig. 2 75-year-old man presenting with swelling of left L5 nerve root in symptomatic extraforaminal stenosis with lumbosacral transitional vertebra. This patient complained of severe left leg pain. Sagittal T1-weighted image (A) of lumbar spine shows transitional lumbosacral junction. Lumbosacral transitional vertebra (arrow) is positioned above transitional disk and axial T1- (B) and T2- (C) weighted images reveal left extraforaminal stenosis (arrow) due to osteophytes at lateral margin of L5 body and degenerative hypertrophy of left ala (thin arrow). Osteophytes (arrow) at right lateral margin of L5 body are noted on axial CT (D). Tilting angle abnormality, swelling of left L5 dorsal root ganglion (small arrow), and exit nerve (arrow) can be seen on 3-dimensional magnetic resonance lumbosacral radiculography (E). Patient obtained complete pain relief after decompression surgery.

• 

  Fig. 3 64-year-old woman presenting with indentation of right L5 nerve root in symptomatic extraforaminal stenosis with lumbosacral transitional vertebra. This patient complained of severe right leg pain. Sagittal T1-weighted image (A) of lumbar spine shows transitional lumbosacral junction. Lumbosacral transitional vertebra (arrow) is positioned above transitional disk. Axial T1- (B) and T2- (C) weighted images reveal right extraforaminal stenosis (arrow) due to osteophytes at lateral margin of L5 body. Osteophytes (arrow) at right lateral margin of L5 body are noted on axial CT (D). Tilting angle abnormality and indentation of right L5 exit nerve (arrow) are seen on 3-dimensional MR lumbosacral radiculography (E). Pain reproduction during selective nerve root injection showed concordant pain.

• 

  Fig. 4 75-year-old man with asymptomatic extraforaminal stenosis. This patient complained of lower back pain without radiculopathy. Axial T1-weighted image (A) shows left extraforaminal stenosis (small arrow) due to hyperplasia and osteophytes (arrow) of sacral ala. 3-dimensional magnetic resonance lumbosacral radiculography (B) revealed no significant morphologic change at left L5 nerve root.

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