Intravenous lidocaine for the emergency department treatment of acute radicular low back pain, a randomized controlled trial

Background: Acute radicular back pain is a frequent complaint of patients presenting to the Emergency Department.

Study objective: Determine the efficacy of intravenous lidocaine when compared to ketorolac for the treatment of acute radicular low back pain.

Methods: Randomized double-blind study of 41 patients aged 18-55 years presenting with acute radicular low back pain. Patients were randomized to receive either 100 mg lidocaine or 30 mg ketorolac intravenously over 2 min. A 100-mm visual analog scale (VAS) was used to assess pain at Time 0 (baseline), and 20, 40, and 60 minutes. Changes in [median] VAS scores were compared over time (within groups) by the signed-rank test and between groups by the rank-sum test. A 5-point Pain Relief Scale (PRS) was administered at the conclusion of the study (60 min) and again at 1 week by telephone follow-up; [median] scores were compared between groups by rank-sum.

Results: Forty-four patients were recruited; 41 completed the study (21 lidocaine, 20 ketorolac). Initial VAS scores were not significantly different between the lidocaine and ketorolac groups (83; 95% confidence interval [CI] 74-98 vs. 79; 95% CI 64-94; p = 0.278). Median VAS scores from baseline to 60 min significantly declined in both groups (lidocaine [8; 95% CI 0-23; p = 0.003]; ketorolac [14; 95% CI 0-28; p = 0.007]), with no significant difference in the degree of reduction between groups (p = 0.835). Rescue medication was required by 67% receiving lidocaine, compared to 50% receiving ketorolac. No significant change in PRS between groups was found at the conclusion or at the follow-up.

Conclusion: Intravenous lidocaine failed to clinically alleviate the pain associated with acute radicular low back pain.