Treatment of Acute Low Back Pain With Transcutaneous Electrical Neurostimulation at the Emergency Department: a Randomized Controlled Trial

Overview

Acute low back pain is a frequent cause of emergency department admissions (4.39% \[95% CI: 3.67-5.18\])1. Drug therapeutic options are limited and ineffective. Paracetamol and opioids are no better than placebo for acute low-back pain 2,3. Only NSAIDs and muscle relaxants have a slightly beneficial effect on pain, but muscle relaxants have an unfavorable risk-benefit balance.2 In this situation, it is necessary to turn to new non-drug therapeutic options to relieve pain of these patients. Transcutaneous electrical nerve stimulation (TENS) is a non-drug therapy that involves applying an electrical current through the skin. Through one or two pairs of electrodes stuck to the skin, TENS delivers painless, low-intensity electrical impulses to a painful area or a nerve pathway. TENS acts by selectively activating large-diameter non-nociceptive afferent fibers to induce segmental analgesia4. In addition, TENS increases the concentration of endorphins in the bloodstream and cerebrospinal fluid5. The use of TENS has been studied mainly in chronic low-back pain. A 2007 Cochrane systematic review concluded that TENS appears to reduce pain and improve range of motion for subjects with chronic low back pain6. The use of TENS in emergency departments has been little studied. A 2018 pilot study of 110 patients admitted to the emergency department with acute or chronic pain observed a reduction in pain (from an average of 8.50 on the numerical pain scale \[EN\] \[7.52 - 9.48\] to 4.67 \[3.51 - 5.89\]) after TENS use and functional improvement in 83% of patients7. The Gulacti study, carried out in 2022, investigated the use of TENS to treat pain of patients admitted to the emergency department with a renal colic attack : the mean reduction in VAS score at 15 and 30 minutes was significantly greater for the TENS group than for the placebo group (mean reduction in VAS score at 15 minutes was 33.3 ± 17.6 (95% CI : 28.3 to 38.3) for the TENS group and 14.9 ± 11.6 (95% CI: 11.6 to 18.2) for the placebo group \[mean difference: 18.4 (95% CI: 12.5 to 24.4, P \< 0.0001)\]. The mean reduction in VAS score after 30 minutes was 63.7 ± 21.1 (95% CI: 57.7 to 69.7) for the TENS group and 14.9 ± 16.2 (95% CI: 19.5 to 10.3) for the placebo group (mean difference: 48.8, 95% CI: 41.4 to 56.3, P \< 0.0001)8. A single study of 76 patients focused on acute low-back pain during patient transport to emergency departments. The authors recorded a significant reduction (p= 0.01) in pain during transport of the TENS group (79.2 ± 6.5 mm VAS to 48.9 ± 8.2 0 mm VAS), while pain scores remained unchanged for the placebo group (75.9 ± 16.4 mm VAS and 77.1 ± 11.2 mm VAS)9. To our knowledge, there is no high-quality study of TENS versus placebo for acute low back pain of patients admitted to an emergency department. 1. Primary objective: Study the analgesic efficacy of TENS compared to placebo in the treatment of acute low back pain at the emergency department. 2. Secondary objective: 1\. Compare the number of patients who will show a \> 50% reduction of their initial pain. 2\. Compare the number of patients requiring rescue treatment. 3. Compare the occurrence of side effects among groups. 4. Compare patient satisfaction after 30 minutes. 5. Compare patient comfort level after 30 minutes. Main criterion: Comparison of the proportion of patients with \>30% reduction of initial pain after 30 minutes of treatment Secondary criterion: 1. Proportion of patients with \> 50% reduction of their initial pain after 30 minutes of treatment. 2. Proportion of patients requiring morphine titration for pain relief. 3. The rate of side-effects associated with the use of TENS. 4. The level of satisfaction measured by numerical satisfaction scale ranging from 0 (not at all satisfied) to 10 (extremely satisfied) EN. A patient will be considered very satisfied if he/she presents a satisfaction level ≥ 8. 5. The level of comfort will be assessed by a comfort scale ranging from 0 (not at all comfortable) to 10 (very comfortable patient).