Control arm of randomized trial
While injecting contrast agents may give patients additional lower extremity radiating pain, additional radiation exposure, or delay in procedure time, care should be taken when they are used in patients with renal disease. Therefore, it is hypothesized that if it is confirmed that the pain caused by the injection needle coincides with the radiating pain that the patient mainly complains of, then the contrast agents may be used less. The purpose of this study is to understand if the identification of lancinating identical pain in the procedure could replace the use of contrast agents.
This retrospective study included 165 patients who met exclusion criteria from among patients who underwent selective nerve root block (SNRB) for the treatment of radiating lower extremity pain from January 2015 to November 2019. With the identical and lancinating pain confirmed in the same site of the patient, consistent with that of the original symptom, the subjects were divided into two groups: one without contrast injection (Non-Dye (ND) group; 57 patients) and the other with contrast injection (Dye (D) group; 108 patients). The degree of lower extremity radiating pain in the two groups was evaluated using visual analog scale (VAS) before injection, 1, 2, 6, and 12 weeks after injection. Functional outcomes were measured using Oswestry Disability Index (ODI) and Rolland Morris Disability Questionnaire (RMDQ), whereas quality of life was measured using Physical Component Score (PCS) and Mental Component Score (MCS) of Short Form – 36 (SF-36) before injection and 3 months after injection.
There was no statistically significant difference in the lower extremity radiating pain severity in both groups at all times and no statistical difference in the degree of VAS improvement relative to the before-injection VAS value between the two groups at 2 and 6 weeks after injection. At 12 weeks after injection, there was a statistically significant difference, with group ND 4.37 ± 2.81 and group D 3.48 ± 2.43 (p = 0.037), but they were below Minimal Clinically Important Difference (MCID), bearing little clinical implications.
Instead of contrast agent injections that have been used for accurate nerve root identification during SNRB, the method of merely checking if the needle-induced pain under fluoroscopic imaging is consistent with the lower extremity radiating pain that the patient predominantly experiences shows the same effect in the patient’s pain control and functional outcome.