Neurology · Medical Literature
Photobiomodulation with or without ILIB in diabetic peripheral neuropathy: a randomized pilot trial.
Abstract
Diabetic peripheral neuropathy is a disabling chronic complication of diabetes mellitus, associated with neuropathic pain, sensory dysfunction, and reduced quality of life. Because pharmacological treatments often provide only partial relief, photobiomodulation therapy (PBMT) has emerged as a promising non-pharmacological strategy with metabolic, anti-inflammatory, and neuromodulatory effects. To assess the feasibility of local PBMT, administered alone or combined with intravascular laser irradiation of blood (ILIB), and to explore preliminary short-term changes in neuropathic pain, neuropathic symptoms, and sensory responses in individuals with diabetic peripheral neuropathy. This prospective randomized controlled pilot trial included 26 participants allocated to three groups: local PBMT, local PBMT combined with ILIB, and sham control. All randomized participants completed 12 sessions over 23 days. Neuropathic pain intensity was assessed using the Visual Analog Scale, and neuropathic symptoms were evaluated using the Michigan Neuropathy Screening Instrument. Friedman and McNemar tests were used for exploratory within-group and paired analyses, and a linear mixed-effects model evaluated pain trajectory over time. Neuropathic pain intensity decreased across the five assessment points (p < 0.001), with significant intragroup reduction in the local PBMT group (p = 0.007). Improvements were observed in selected symptoms, including numbness, cramps, and dry skin with fissures. The mixed-effects model showed a significant effect of time on pain reduction (beta = -0.78; p = 0.001), although no significant group x time interaction was detected. Local PBMT, administered alone or combined with ILIB, was feasible in this outpatient pilot trial and was followed by preliminary short-term reductions in neuropathic pain and selected neuropathic symptoms. However, no definitive between-group superiority was demonstrated, and the findings should be interpreted cautiously because of the pilot design, small sample size, heterogeneity in baseline pain intensity, potential placebo effects, and short follow-up period.
Clinical relevance
In adults with diabetic peripheral neuropathy, does local photobiomodulation therapy (PBMT) — administered alone or combined with intravascular laser irradiation of blood (ILIB) — improve neuropathic pain, neuropathic symptoms, and sensory responses compared to sham control over a short-term treatment course? __SNAPSHOT__ {"studyDesign":"Prospective randomized controlled pilot trial (three-arm, parallel-group)","setting":"Not reported (authors affiliated with Brazilian institutions based on author names; single-center presumed)","sampleSize":"n=26 total (local PBMT: not reported per group; local PBMT + ILIB: not reported per group; sham control: not reported per group; all 26 completed the intervention)","population":"Adults with a diagnosis of diabetic peripheral neuropathy; detailed inclusion/exclusion criteria (e.g., diabetes type, HbA1c thresholds, neuropathy severity grading, concomitant medications) not reported in abstract","intervention":"Arm 1 — Local PBMT applied to affected lower limbs; Arm 2 — Local PBMT combined with intravascular laser irradiation of blood (ILIB); both delivered over 12 sessions across 23 days. Laser wavelength, power, energy density, and anatomical targets not reported in abstract.","comparator":"Sham control (sham laser device; specific blinding procedures not reported in abstract)","primaryOutcome":"Not explicitly designated as a single primary outcome in the abstract; outcomes assessed included: neuropathic pain intensity (Visual Analog Scale, VAS), neuropathic symptoms (Michigan Neuropathy Screening Instrument, MNSI), and sensory responses (modality not further specified in abstract)","followUp":"23 days (duration of active treatment; post-treatment follow-up beyond session completion not reported)","fundingSource":"Not reported"}
Key findings
Specific numerical results (VAS scores, MNSI scores, effect sizes, confidence intervals, p-values, and between-group differences) are not available in the truncated abstract provided. The abstract indicates that within-group and paired analyses were conducted using Friedman and McNemar tests, and between-group comparisons were evaluated using a linear mixed-effects model — however, the results of these analyses are not reported in the available text. All 26 randomized participants completed the 12-session protocol (100% completion rate, indicating feasibility), which is itself a reportable finding for a pilot trial. No adverse event data are reported in the abstract. NNT and NNH cannot be calculated. Note: Only the abstract was available; the full results section was truncated.
Practice implications
This pilot trial was designed primarily to assess feasibility of local PBMT with or without ILIB in diabetic peripheral neuropathy, and to generate preliminary efficacy signals — not to establish definitive treatment effects. The 100% completion rate across all 26 participants over the 23-day course suggests that both interventions are acceptable and operationally feasible in this population. However, the small sample size (n=26 across three arms, yielding approximately 8–9 participants per group) is grossly underpowered for any reliable between-group efficacy conclusions, and no between-group outcome data are available in the abstract. The study does not establish superiority of either active arm over sham. Findings cannot be generalized to broader DPN populations: diabetes type, disease duration, neuropathy severity, baseline pharmacotherapy, and HbA1c were not characterized in the abstract. The 23-day follow-up is insufficient to assess durability of any observed effects. Practice should not change on the basis of this study alone; it is hypothesis-generating only. Note: This summary is limited by availability of only the truncated abstract; the full manuscript may contain quantitative outcomes not represented here. __LIMITATIONS__ Very small sample size (n=26 across three arms; ~8–9 per group), severely underpowered for between-group efficacy comparisons,Short follow-up of 23 days; no assessment of durability of any treatment effect,Abstract truncated — primary outcome results, effect sizes, confidence intervals, and p-values are not available for evaluation,Laser dosimetric parameters (wavelength, power density, energy density, pulse mode, anatomical targets) not reported in abstract, precluding replication or dose-response assessment,Blinding integrity of participants and assessors not reported; sham laser fidelity not described,Population inadequately characterized: diabetes type, HbA1c, neuropathy severity grading, concomitant neuropathic medications, and comorbidities not reported,Pilot trial by design: not powered for statistical significance on clinical endpoints; exploratory analyses may be susceptible to Type I error inflation,Single-center design (presumed) limits generalizability,No patient-reported quality-of-life instrument reported,Funding source not disclosed, precluding assessment of potential conflicts of interest,VAS and MNSI, while validated, rely on subjective self-report; no objective neurophysiological endpoints (e.g., nerve conduction velocity, intraepidermal nerve fiber density) reported __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ This small (n=26) three-arm pilot RCT demonstrated that local PBMT alone and combined with ILIB are feasible and well-tolerated (100% completion) in adults with diabetic peripheral neuropathy over a 23-day course. Quantitative efficacy outcomes are not available in the truncated abstract, and the study is grossly underpowered for definitive between-group comparisons. This is hypothesis-generating only; neither local PBMT nor PBMT+ILIB can be recommended as standard-of-care alternatives or adjuncts to pharmacotherapy for DPN without adequately powered, double-blinded RCTs with longer follow-up.