Impact of Intramuscular Electrical Stimulation on Multifidus Muscle Function in Chronic Low Back Pain: A Randomized Controlled Trial

BACKGROUND Despite advances in conservative back pain treatments, optimal methods for restoring multifidus muscle function - especially via neuromodulation like intramuscular electrical stimulation (IMES) - remain under investigation. This study evaluated the effects of a 6-week IMES protocol on multifidus muscle properties in individuals with chronic low back pain. MATERIAL AND METHODS In a randomized controlled trial, 29 participants (mean age: 39.2±10.9 years) were assigned to either a control group (receiving transcutaneous electrical nerve stimulation [TENS], myofascial trigger point therapy, and exercise), or an experimental group (same therapy but with IMES replacing TENS, applied via acupuncture needles under ultrasound guidance). Outcomes included muscle stiffness (MS), tension (MT), tissue perfusion (TP), pressure pain threshold (PPT), pain rating (NRS), postural stability (PS), range of motion (ROM), and maximal voluntary contraction (MVC). Assessments were conducted at baseline, immediately after treatment, and at follow-up 4 weeks later using validated instruments. RESULTS Compared to controls, the IMES group showed significant improvements after treatment and at follow-up in MT right, TP (right and left), PPT left, NRS, ROM, and PS (P values ranging from <0.001 to 0.006). No significant changes were found in MS (right or left) or MVC at any time point, nor in TP (right and left) at 4 weeks. CONCLUSIONS IMES combined with standard therapy significantly improves muscle tension, perfusion, pain threshold, intensity, ROM, and postural stability in chronic low back pain patients, outperforming standard therapy with TENS. However, causality remains uncertain due to both protocols being embedded in multimodal treatment.