Contrast Spread in the Superoposterior Approach of Transforaminal Epidural Steroid Injections for Lumbosacral Radiculopathy

Abstract

Objective: To observe the contrast spread in superoposterior transforaminal epidural steroid injection (SP TFESI) and investigate the correlation between spread patterns and efficacy.

Methods: Thirty-one patients with lumbosacral radiculopathy underwent single-level TFESI under fluoroscopy. The final needle tip position was targeted toward the SP quadrant of the intervertebral foramen. To observe the spread, 1 mL of contrast material was injected, followed by a steroid injection. The contrast spread was graded anteroposteriorly and vertically in the epidural space. The effect of SP TFESI was evaluated by proportional pain score reduction.

Results: Levels injected were L4-5 (n=20) and L5-S1 (n=11). Seventeen cases were lateral, and 14 were central herniated disc (HD). Baseline mean visual analog scale score was 6.23. Contrast dispersed dorsally in all the cases, and 45.2% cases showed a concurrent ventral spread. The proportion of the pain reduction after 2 weeks showed no difference between the two groups. In vertical spreading analysis, mean cephalic/caudal grades were 1.40/1.55 at L4-5 level and 1.73/1.64 at L5-S1 level. The HD location had no effect on contrast dispersion.

Conclusion: In SP TFESI, ventral contrast spread did not guarantee a better effect; however, the extent of cephalic flow in ventral expansion group correlated with the proportion of pain reduction.

Keywords: Contrast media; Epidural injection; Lumbosacral; Radiculopathy; Treatment outcome.

Fig. 1. CT myelography showing L3, L4, and L5 nerve roots. Openings of the dural sleeves span the upper half of the pedicles at L3, L4, and L5 vertebrae. CT, computed tomography.

Fig. 2. Vertical spread grading system on a schematic drawing of lumbar vertebra with epidural spaces (anteroposterior view). Grade was determined by the spreading extent of contrast from injection level in both the cephalic and caudal directions separately. IVD, intervertebral disc.

Fig. 3. Anteroposterior (A) and lateral (B) fluoroscopic view of L5-S1 SP TFESI. Contrast filled the dorsal epidural space and spread to the ventral space. Vertical dispersal analysis showed Grade 3 (above the superior IVD, not exceeding the horizontal midline of the upper level pedicle) in the cephalic direction and Grade 2 (within the vertical level of the inferior IVD) in the caudal direction. SP TFESI, superoposterior transforaminal epidural steroid injection; IVD, intervertebral disc.