Clinical outcomes of low versus high intensity laser therapy in patients with subacute carpal tunnel syndrome: A randomized, single-blinded, controlled trial

A common entrapment of median nerve that causes pain, numbness, and functional impairment is called Carpal Tunnel Syndrome (CTS). Laser therapy is a noninvasive intervention for neural repair and pain modulation, but comparative evidence between Low-Level Laser Therapy (LLLT) and High-Intensity Laser Therapy (HILT) in subacute CTS is limited. The aims of this study were to compare the effects of LLLT and HILT on pain, functional status, electrophysiological, and ultrasonographic parameters in subacute CTS. A single-blinded randomized controlled trial (Reg. No. IRCT20241111063665N1) was conducted at the Department of Physiotherapy, The University of Lahore (UOL), Lahore, Pakistan, from August 2024 to March 2025. Sixty-nine participants with subacute CTS, confirmed by electromyography and nerve conduction studies, were randomly assigned to three groups (n = 23 each): Group A (HILT; 808 nm + physiotherapy), Group B (LLLT; 860 nm + physiotherapy), and Group C (physiotherapy + sham laser). Assessments were at baseline and week 6. Outcomes included pain (VAS), symptom severity and functional status (Boston Carpal Tunnel Questionnaire; BCTQ), grip strength, distal motor latency (DML), sensory nerve conduction velocity (SNCV), and median nerve cross-sectional area (CSA). ANCOVA with Bonferroni correction and effect size estimation was applied. At week 6, both HILT and LLLT showed significant improvements (p < 0.001). HILT achieved greater pain reduction (- 4.9) than LLLT (- 4.1) and control (- 2.2; p < 0.001), with greater improvement in BCTQ-SSS (- 2.2 points), BCTQ-FSS (- 1.9 points), grip strength (+ 9.9 kg), DML (- 1.2 ms), SNCV (+ 12.3 m/s), and CSA (- 3.7 mm²). Large effect sizes (Cohen's d > 0.8) were observed. Both LLLT and HILT are effective as adjuncts to physiotherapy in subacute CTS. HILT demonstrated greater improvements than LLLT within the parameters tested.Clinical Trial Number: IRCT20241111063665N1, Registration date: 17 March, 2025.