Peripheral nerve injury (PNI) is associated with considerable functional impairment. Photobiomodulation (PBM) has demonstrated positive effects regarding neuromuscular repair after PNI when applied locally to the nerve or injured muscle. However, the effects of systemic PBM with transcutaneous application over an important artery, which is also denominated vascular PBM (VPBM), remain unclear. The aim of the study was to compare the effects of VPBM with low-level laser (LLL) and light-emitting diode (LED) on gait, sensitivity and muscle morphology following a PNI. PNI was induced on Wistar rats using the sciatic nerve crushing technique. VPBM was performed over the rat's artery tail region with LED (850 nm, 40 mW, 3.2 J) and LLL (780 nm, 40 mW, 3.2 J). Gait functionality, mechanical (nociceptive) sensitivity, and morphology of the tibialis anterior muscle were evaluated at 7, 14, and 21 days after injury. An improvement in functional gait was shown in the VPBM-LLL group in all periods. Motor sensitivity was found after 14 days in the VPBM-LLL group. The left/right (L/R) muscle mass ratio revealed a reduction in muscle atrophy in the VPBM-LLL group at 7 days. Muscle fiber diameter increased in the VPBM-LED group at 14 days and increases in the cross-section area were found in the VPBM-LED and VPBM-LLL groups at 7 days. VPBM with both light sources (LED and LLL) positively modulated functioning and neuromuscular recovery following sciatic nerve injury in rats, with more pronounced results when using LLL.

This systematic review investigated the repercussions of photobiomodulation using lowlevel laser therapy (LLLT) for the treatment of spinal cord injury (SCI) in experimental models. Studies were identified from relevant databases published between January 2009 and December 2021. Nineteen original articles were selected and 68.4% used light at an infrared wavelength. There was a considerable variation of the power used (from 25 to 200 mW), total application time (8-3000 s) and total energy (0.3-450 J). In 79% of the studies, irradiation was initiated immediately after or within 2 h of the SCI, and treatment time ranged continuously from 5 to 21 days. In conclusion, LLLT can be an auxiliary therapy in the treatment of SCI, playing a neuroprotective role, enabling functional recovery, increasing the concentration of nerve connections around the injury site and reducing pro-inflammatory cytokines. However, there is a need for standardization in the dosimetric parameters.

The local photobiomodulation (LPBM) has demonstrated positive effects during compensatory hypertrophy (CH) in skeletal muscle as a response to an overload. The aim was to compare the effects of the transcutaneous vascular photobiomodulation (VPBM) and the LPBM on muscle fiber size, gait functionality, and on mechanical sensitivity during the CH model in rats. VPBM was administered over the rat's main tail vein and LPBM was applied over the plantar muscle region. VPBM induced an increase in muscle fiber diameter and cross‐sectional area (CSA) after 7 days. At 14 days, an increase in the fiber diameter was found in both irradiated groups. The VPBM and LPBM promoted the reestablishment of normal gait evaluated by the sciatic functional index after 14 days. No changes were found in the mechanical (nociceptive) sensitivity in VPBM and LPBM groups in comparison to the CH group but there was an increase in the nociceptive sensitivity in the CH groups in comparison to the control after 7 and 14 days. In conclusion, both PBM, vascular and local, were able to improve the muscle size and gait during the CH process with more pronounced effects when irradiation was performed systemically (VPBM).

Introduction Myelomeningocele is a severe type of spina bifida, resulting from improper closure of the neural tube. This condition drastically affects the structures of the spinal cord resulting in deficiencies. The combination of these deficiencies results in an overall decrease in mobility and functional participation amongst this population. Physiotherapy plays an essential role in rehabilitating people with MMC. The current literature shows that resources such as photobiomodulation (PBM) may support the rehabilitation of neurological conditions. The aim of the proposed study is to evaluate the effects of photobiomodulation (PBM) combined with physical therapy on functional performance in children with low lumbosacral myelomeningocele. Materials and methods This is a protocol randomized clinical blind study, that will include 30 individuals of both sexes, aged between 5 to 8 years, diagnosed with low and sacral lumbar myelomeningocele and capable of performing the sit-to-stand task. The participants will be randomly assigned into two treatment groups: PBM + physiotherapeutic exercises and sham PBM + physiotherapeutic exercises. Irradiation will be carried out with light emitting diode (LED) at a wavelength of 850 nm, energy of 25 J per point, 50 seconds per point and a power of 200 mW. The same device will be used in the placebo group but will not emit light. Muscle activity will be assessed using a portable electromyograph (BTS Engineering) and the sit-to-stand task will be performed as a measure of functioning. Electrodes will be positioned on the lateral gastrocnemius, tibialis anterior and rectus femoris muscles. The Pediatric Evaluation of Disability Inventory will be used to assess functional independence. Quality of life will be assessed using the Child Health Questionnaire—Parent Form 50. Changes in participation will be assessed using the Participation and Environment Measure for Children and Youth. The data will be analyzed with the aid of GraphPad PRISM. Discussion The results of this study can contribute to a better understanding of the effectiveness of PBM on functioning and quality of life in children with myelomeningocele. Clinical trial registration ClinicalTrials.gov Identifier: NCT04425330.

Objectives: Spinal cord injury (SCI) causes the discontinuity of the spinal canal, leading to functional and sensorial losses in areas below the injury, which are often irreversible. Photobiomodulation (PBM) can enhance the neuromuscular repair process, especially in cases of peripheral nerve injuries. However, there is little knowledge regarding the effects of this therapeutic modality on recovery following a SCI, especially the noninvasive systemic form denominated vascular PBM (VPBM). To analyze the effects of VPBM in the immediate, acute and intermediate phases following a compression-induced SCI on morphological aspects of neuromuscular tissue repair, functional recovery and the protein expression of brain-derived neurotrophic factor (BDNF). Methods: Wistar rats were divided into five groups: control, SCI, SCI + VPBM-Im (immediate administration of VPBM), SCI + VPBM-2h (VPBM administered 2 h after injury) and SCI + VPBM-14d (VPBM administered 14 days after injury). VPBM was administered in the region of the caudal vein/artery with low-level laser (AsGaAl, 780 nm, 80 J/cm², 40 mW for 80 s, totaling an energy of 3.2 J over a single point) for 14 consecutive days. During the analysis periods (1, 3, 7, 14, 21, 28 and 35 days after injury), functioning was evaluated using the Basso-Beattie-Bresnahan (BBB) index. At the end of each experimental period, blood samples were collected for the determination of the concentration of circulating BDNF using ELISA. Muscle tissue and nerve tissue samples were also extracted for morphological and histological analyses using H&E staining. Results: SCI + VPBM-Im and SCI + VPBM-2 h led to the recovery of motor function beginning on the 7th day after injury (p < 0.05), an increase in the crosssectional area (CSA) of the muscle fibers in the second week (p < 0.05) and an increase in muscle fiber diameter beginning on Day 14 (p < 0.05). Early irradiation had a greater effect on the reduction in the size of the cavity, with stabilization of the cavity found on Day 7 (p < 0.05). Considering the circulating BDNF levels, no changes was found during the experimental periods. Conclusion:The present results showed that VPBM was capable of modulating morphological and functional recovery following SCI, especially when administered early. The positive effects on functional recovery were demonstrated by the BBB index; the reestablishment of the structure of the muscle and nerve tissue was demonstrated by the preservation of CSA and diameter of muscle fiber and reduction in the area of the injury (cavity size) respectively. Thus, noninvasive VPBM may be an important component of treatment for spinal cord injuries.