Photobiomodulation for Median Nerve Neuroplasticity in Carpal Tunnel Syndrome: A Randomized Controlled Trial (PBM-CTS-RCT)

Therapeutic Effects of Photobiomodulation (Low Level Laser Therapy) on Median Nerve Neuroplasticity in Patients With Carpal Tunnel Syndrome

Carpal Tunnel Syndrome (CTS) is the most common peripheral entrapment neuropathy, causing pain, paresthesia, and hand dysfunction due to median nerve compression at the wrist. While physiotherapy provides symptom relief, it does not effectively address the underlying neuroplastic deficits of the median nerve. Photobiomodulation (PBM), delivered at 830 nm near-infrared wavelength, has shown potential to enhance peripheral nerve regeneration via cytochrome c oxidase activation, ATP synthesis, and upregulation of neurotrophic factors including brain-derived neurotrophic factor (BDNF). This randomized controlled trial will evaluate whether 830 nm PBM (200 mW, 4 J/cm², 12 sessions over 4 weeks) combined with routine physiotherapy produces significantly greater neuroplastic recovery of the median nerve - assessed by high-resolution ultrasound (HRUS) measurement of median nerve cross-sectional area (CSA), nerve conduction study parameters and serum BDNF - compared to sham PBM combined with identical physiotherapy in adults with mild-to-moderate CTS. Neuroplasticity was operationalised as a multimodal construct comprising: (1) functional recovery, indexed by nerve conduction study parameters; (2) structural remodelling, indexed by median nerve cross-sectional area on high-resolution ultrasound; and (3) molecular neuroplastic signalling, indexed by serum BDNF. This multimodal approach was adopted because no single measure captures the full construct of peripheral nerve neuroplasticity (Padua et al., 2020).

Study Overview

• Status: Not yet recruiting
• Conditions: Carpal Tunnel Syndrome (CTS)
• Intervention / Treatment: Device: Photobiomodulation (Low-Level Laser Therapy); Other: Routine Physiotherapy Programme; Device: Sham Photobiomodulation

Detailed Description

Carpal tunnel syndrome is a compressive neuropathy of the median nerve associated with focal demyelination, impaired axonal transport, intraneural oedema, pain, sensory disturbance and functional limitation. Although conservative treatments can reduce symptoms, the physiological and structural processes accompanying median nerve recovery remain insufficiently characterized.

Photobiomodulation delivers non-thermal red or near-infrared light to biological tissue. Its proposed effects include modulation of mitochondrial activity, cellular energy production, oxidative signalling and inflammatory responses. Experimental evidence also suggests potential effects on Schwann-cell activity, axonal repair and neurotrophic signalling. However, clinical studies of photobiomodulation for carpal tunnel syndrome have generally been limited by small samples, heterogeneous treatment parameters and reliance on symptomatic outcomes without integrated assessment of nerve physiology, morphology and molecular responses.

This study will investigate whether adjunctive 830-nm photobiomodulation produces greater median nerve recovery than sham photobiomodulation when both groups receive the same routine physiotherapy. The primary hypothesis is that active photobiomodulation will produce greater improvement in median nerve sensory conduction velocity at the end of the four-week intervention. Follow-up assessment will examine whether any observed effect is maintained after treatment completion.

Electrophysiological testing will characterize changes in median nerve function, while high-resolution ultrasonography will assess structural changes in the nerve. Serum brain-derived neurotrophic factor will be evaluated as an exploratory circulating biomarker and will not be interpreted as a specific standalone measure of median nerve neuroplasticity. Patient-reported symptoms, functional status, pain and hand strength will be assessed to determine the clinical relevance of any physiological or structural changes.

By integrating electrophysiological, ultrasonographic, clinical and exploratory molecular measurements, the study aims to clarify whether the symptomatic effects of photobiomodulation are accompanied by objective evidence of median nerve recovery. The findings may help refine outcome selection and treatment parameters for future confirmatory trials.

• Study Type: Interventional
• Enrollment (Estimated): 70
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Sajid Mehmood, MS (OMPT); Phone Number: 923218486974; Email: drmsajidphy@gmail.com
• Study Contact Backup: Name: Dr Ashfaq Ahmad, PhD; Phone Number: 923009449192; Email: ashfaq.ahmad@uipt.uol.edu.pk

Study Locations

• Pakistan
  • Punjab Province
    • Lahore, Punjab Province, Pakistan, 54000
      • University of Lahore Hospital
      • Contact: umair ahmed, PhD; Phone Number: 00923212700817; Email: umair.ahmed@uipt.uol.edu.pk
      • Contact: Dr Ishaq Ahmad, PhD; Phone Number: 923344066463; Email: ishaq.ahmad@uipt.uol.edu.pk
      • Principal Investigator: Dr Sajid Mehmood, MS (OMPT)

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion criteria

• Age 18-60 years
• Clinical diagnosis of unilateral mild-to-moderate carpal tunnel syndrome based on positive Phalen test and/or Tinel sign
• Electrophysiological confirmation of CTS via nerve conduction study (NCS) meeting AANEM 2012 diagnostic criteria for mild-to-moderate CTS
• No prior photobiomodulation or laser therapy to the affected wrist within the preceding 3 months
• Ability to attend 3 treatment sessions per week for 4 consecutive weeks
• Able and willing to provide written informed consent (in Urdu or English)

Exclusion Criteria

• Bilateral carpal tunnel syndrome
• Previous surgical release of the carpal tunnel on the affected side
• Systemic peripheral neuropathy (e.g., diabetes mellitus, hypothyroidism, Charcot-Marie-Tooth disease)
• Pregnancy or breastfeeding
• Implanted cardiac pacemaker, defibrillator, or other active electronic implant
• Active malignancy at or near the treatment site
• Current use of photosensitising medications (e.g., tetracyclines, amiodarone, psoralens)
• Corticosteroid injection into the carpal tunnel within the preceding 3 months
• Rheumatoid arthritis or other inflammatory joint disease affecting the wrist
• Open wounds, acute skin infection, or tattooed skin at the treatment site
• Inability to attend 3 sessions per week for 4 weeks
• Severe CTS confirmed by NCS (complete sensory or motor axon loss)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Group A - Active PBM + Routine PT; 830 nm photobiomodulation (200 mW, 46-diode cluster probe, 4 J/cm², continuous wave) applied over the carpal tunnel region (volar wrist), 3 sessions/week for 4 weeks (12 sessions total). Combined with wrist splinting in neutral position (nocturnal) and median nerve gliding exercises (3 × 10 reps twice daily).	Device: Photobiomodulation (Low-Level Laser Therapy); Photobiomodulation (PBM) delivered using a 46-diode cluster probe at 830 nm wavelength, 200 mW optical output power, continuous wave mode, 4 J/cm² energy density, applied in static contact technique over the carpal tunnel (volar wrist surface, 3-5 cm proximal to distal wrist crease). Application time per session: approximately 200 seconds (~3.3 minutes). Treatment schedule: 3 sessions per week for 4 consecutive weeks (12 sessions total). Sham device output confirmed <1 mW by calibrated photodiode power meter.; Other Names: LLLT; Low-Level Laser Therapy; Low-Level Light Therapy; PBMT; Other: Routine Physiotherapy Programme; Participants will receive an 4-week routine physiotherapy programme comprising median nerve mobilization, night splinting, and tendon-gliding exercises. Median nerve mobilization will use six sequential positions progressing from wrist-neutral finger/thumb flexion to finger, wrist, and thumb extension, forearm supination, and assisted thumb stretching. Each position will be held for 5 seconds; the sequence will be repeated 10 times, three times daily. A neutral volar wrist splint allowing free finger and thumb movement will be worn nightly for 6-8 hours. Tendon-gliding exercises will include straight hand, hook fist, full fist, tabletop, and straight fist positions. Each position will be held for 5 seconds, with 10 repetitions performed three times daily. A physiotherapist will teach and monitor the programme. Participants will receive illustrated instructions and maintain an adherence diary. Exercises will be modified or stopped if symptoms worsen.; Other Names: Conventional Physiotherapy; Multimodal Physiotherapy Programme; Standard Conservative Physiotherapy
Sham Comparator: Group B - Sham PBM + Routine PT; Identical procedure using a deactivated PBM device (confirmed output <1 mW by calibrated power meter). Same probe, contact time, and positioning as Group A. Combined with identical routine physiotherapy (wrist splinting + nerve gliding exercises).	Other: Routine Physiotherapy Programme; Participants will receive an 4-week routine physiotherapy programme comprising median nerve mobilization, night splinting, and tendon-gliding exercises. Median nerve mobilization will use six sequential positions progressing from wrist-neutral finger/thumb flexion to finger, wrist, and thumb extension, forearm supination, and assisted thumb stretching. Each position will be held for 5 seconds; the sequence will be repeated 10 times, three times daily. A neutral volar wrist splint allowing free finger and thumb movement will be worn nightly for 6-8 hours. Tendon-gliding exercises will include straight hand, hook fist, full fist, tabletop, and straight fist positions. Each position will be held for 5 seconds, with 10 repetitions performed three times daily. A physiotherapist will teach and monitor the programme. Participants will receive illustrated instructions and maintain an adherence diary. Exercises will be modified or stopped if symptoms worsen.; Other Names: Conventional Physiotherapy; Multimodal Physiotherapy Programme; Standard Conservative Physiotherapy; Device: Sham Photobiomodulation; Deactivated PBM device identical in external appearance to the active device. Applied using the same 46-diode cluster probe, contact technique, and duration (approximately 200 seconds) as the active arm. Output power confirmed <1 mW by calibrated photodiode power meter (LaserCheck or equivalent) at baseline, session 6, and session 12 for the first five enrolled participants. No therapeutic light emission occurs.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Median Nerve Sensory Conduction Velocity at Week 4 and week 8	Median nerve sensory conduction velocity will be measured in metres per second (m/s) using a standardized nerve conduction study performed by a blinded neurophysiologist. Electrode placement, stimulation distance, equipment settings and skin temperature will be standardized across assessments. Change will be calculated as the Week 4 and 8 value minus the baseline value. A positive change indicates improvement in sensory conduction velocity.	Baseline, Week 4 and week 8

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Median Nerve Distal Motor Latency	Median nerve distal motor latency will be measured in milliseconds (ms) using a standardized nerve conduction study, with stimulation at the wrist and recording from the abductor pollicis brevis muscle. The same stimulation distance, electrode placement, equipment settings and skin-temperature controls will be used at each assessment. Change will be calculated as the follow-up value minus the baseline value. A negative change indicates reduced latency and improved motor conduction.	Baseline, Week 4 and Week 8
Change From Baseline in Median Nerve Sensory Nerve Action Potential Amplitude	Median nerve sensory nerve action potential amplitude will be measured in microvolts (µV) using a standardized nerve conduction study performed by a blinded neurophysiologist. The same recording technique and equipment settings will be used at each assessment. Change will be calculated as the follow-up value minus the baseline value. A positive change indicates an increase in sensory response amplitude.	Baseline, Week 4 and Week 8
Change From Baseline in Median Nerve Cross-Sectional Area	The cross-sectional area of the median nerve will be measured in square millimetres (mm²) using high-resolution ultrasonography at the carpal tunnel inlet at the level of the pisiform. The nerve will be traced within the hyperechoic epineurial border. Three measurements will be obtained and averaged at each assessment. The same anatomical level, participant position, ultrasound settings and blinded assessor will be used throughout the study. Change will be calculated as the follow-up value minus the baseline value. A negative change indicates a reduction in median nerve enlargement.	Baseline, Week 4 and Week 8
Change From Baseline in Boston Carpal Tunnel Questionnaire Symptom Severity Scale Score	Symptom severity will be assessed using the 11-item Symptom Severity Scale of the Boston Carpal Tunnel Questionnaire. Each item is scored from 1 to 5, and the subscale score is calculated as the mean of the completed items. Total subscale scores range from 1 to 5, with higher scores indicating more severe symptoms. Change will be calculated as the follow-up score minus the baseline score. A negative change indicates improvement	Baseline, Week 4 and Week 8
Change From Baseline in Boston Carpal Tunnel Questionnaire Functional Status Scale Score	Functional status will be assessed using the 8-item Functional Status Scale of the Boston Carpal Tunnel Questionnaire. Each item is scored from 1 to 5, and the subscale score is calculated as the mean of the completed items. Total subscale scores range from 1 to 5, with higher scores indicating greater functional limitation. Change will be calculated as the follow-up score minus the baseline score. A negative change indicates improvement.	Baseline, Week 4 and Week 8
Change From Baseline in Pain Intensity Measured Using the Visual Analogue Scale	Pain intensity will be measured using a 100-mm horizontal Visual Analogue Scale, ranging from 0 mm, representing no pain, to 100 mm, representing the worst imaginable pain. Change will be calculated as the follow-up score minus the baseline score. A negative change indicates reduced pain intensity.	Baseline, Week 4 and Week 8
Change From Baseline in Handgrip Strength	Handgrip strength of the affected hand will be measured in kilograms (kg) using a Jamar hydraulic hand dynamometer and standardized positioning. Three trials will be performed with a standardized rest period between trials, and the mean of the three measurements will be used for analysis. Change will be calculated as the follow-up value minus the baseline value. A positive change indicates improved grip strength.	Baseline, Week 4 and Week 8
Number of Participants With Treatment-Emergent Adverse Events	Treatment-emergent adverse events will be recorded from the first intervention session through the final follow-up assessment. Events will include, but will not be limited to, increased wrist or hand pain, skin irritation, erythema, burning sensation, altered sensation, headache or any other unfavorable medical occurrence. The number and percentage of participants experiencing one or more adverse events will be reported for each intervention group.	From the first intervention session through Week 8

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Serum Brain-Derived Neurotrophic Factor Concentration	Serum brain-derived neurotrophic factor concentration will be measured in picograms per millilitre (pg/mL) using a standardized enzyme-linked immunosorbent assay. Blood collection time, clotting duration, centrifugation, storage temperature, freeze-thaw exposure and assay procedures will be standardized across assessments. Samples from both intervention groups will be analysed in the same assay batches where feasible. Change will be calculated as the follow-up concentration minus the baseline concentration. This outcome will be interpreted as an exploratory circulating biomarker and not as a specific standalone measure of median nerve neuroplasticity.	Baseline, Week 4 and Week 8

Collaborators and Investigators

• Sponsor: University of Lahore
• Investigators: Principal Investigator: Dr Sajid Mehmood, MS (OMPT), University of Lahore; Study Director: Dr Ashfaq Ahmad, PhD, University of Lahore; Study Chair: Dr Umair Ahmed, PhD, University of Lahore; Study Chair: Dr Ishaq Ahmed, PhD, University of Lahore

Study record dates

Study Major Dates

• Study Start (Estimated): August 15, 2026
• Primary Completion (Estimated): May 15, 2027
• Study Completion (Estimated): August 15, 2027

Study Registration Dates

• First Submitted: July 15, 2026
• First Submitted That Met QC Criteria: July 15, 2026
• First Posted (Actual): July 20, 2026

Study Record Updates

• Last Update Posted (Actual): July 20, 2026
• Last Update Submitted That Met QC Criteria: July 15, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Randomized Controlled Trial; Ultrasonography; Photobiomodulation; Physical Therapy Modalities; Carpal Tunnel Syndrome; Brain-Derived Neurotrophic Factor; Nerve Conduction Studies; Low-Level Light Therapy; Neuronal Plasticity; Median Nerve
• Additional Relevant MeSH Terms: Nervous System Diseases; Wounds and Injuries; Neuromuscular Diseases; Peripheral Nervous System Diseases; Median Neuropathy; Mononeuropathies; Nerve Compression Syndromes; Cumulative Trauma Disorders; Sprains and Strains; Carpal Tunnel Syndrome; Therapeutics; Laser Therapy; Phototherapy; Low-Level Light Therapy
• Other Study ID Numbers: REC/019/25/6332

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data underlying the published results will be shared. These data will include coded participant identifiers, treatment allocation, baseline demographic and clinical characteristics, treatment attendance and adherence, nerve conduction measurements, median nerve cross-sectional area, serum BDNF concentration, BCTQ symptom and functional scores, pain intensity, grip strength, adverse events and missing-data indicators at baseline, Week 4 and Week 8. Derived analysis variables and a data dictionary will also be provided. Names, contact information, exact dates, signed consent forms, biological samples and other potentially identifying information will not be shared.
• IPD Sharing Time Frame: The de-identified IPD and supporting information will become available beginning 6 months after publication of the primary study results and will remain available for 5 years.
• IPD Sharing Access Criteria: De-identified IPD and supporting materials will be available to qualified researchers submitting a methodologically sound proposal with a clearly defined scientific purpose. Requests will be reviewed by the Principal Investigator and institutional sponsor. Research ethics approval may be required depending on the proposed analysis. Approved researchers must sign a data-use agreement prohibiting participant re-identification, unauthorized redistribution and use beyond the approved purpose. Data will be provided through a secure repository or encrypted transfer. Requests should be directed to the Principal Investigator using the contact information in this ClinicalTrials.gov record.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No