Relationship of dorsal root ganglion to intervertebral foramen in lumbar region: an anatomical study and review of literature.

BACKGROUND: The purpose of this study was to clarify the morphologic features, location and variations of the dorsal root ganglion (DRG). METHODS: Fifteen formalin fixed cadavers for the current study were included. Total of 150 DRGs were examined from L1 to L5. The relationships of the nerve root DRGs to the intervertebral foramen were noted. Position of the DRG was classified by the location of the ganglia in relation to the pedicle. The relationship of the DRG to the intervertebral foramen was evaluated. RESULTS: The distance between the midpoint of the DRG to the cross section of the root with the medial border of the pedicle gradually increased from L1 to L5. The medial border of the foramen distances along the nerve root were L1, 1.77 mm; L2, 2.79 mm; L3, 3.23 mm; L4, 7.28 mm and L5, 8.31 mm. The mean width of the lumbar DRGs were L1, 4.36 mm; L2, 4.56 mm; L3, 4.99 mm; L4, 5.22 mm and L5, 5.82 mm. The mean length of DRGs were as follows: L1, 5.39 mm; L2, 5.83 mm; L3, 7.24 mm; L4, 7.97 mm and L5, 10.83 mm. The mean width and length of DRGs gradually increased from L1 to L5. CONCLUSIONS: The DRG in the lumbar region play a key role in the occurence of low-back pain and sciatica; therefore, it is important to understand the anatomy of DRG. The accurate anatomic information about the position of DRGs would be useful to perform a safe surgical intervention in the lumbar foraminal region.