On-Site Laser Photobiomodulation Treatment of Crushed Muscle Due to Prolonged Pressure in Rats.

BACKGROUND AND OBJECTIVES: Crush injuries and prolonged pressure on muscles lead to bruises and sprains and, in most of the cases, cause distraction of the muscle and release of particles into the blood stream, causing renal and systemic complications in severe cases. Laser photobiomodulation treatment (i.e., laser phototherapy) is a method suggested to decrease the pressure damage in the first 24-48 hours after muscle injury, allowing a faster and more complete physical rehabilitation. We studied the efficacy of non-invasive laser photobiomodulation treatment as an on-site treatment for crush-injured gastrocnemius muscles, developing a moderate muscle crush injury model and aiming at decreasing damage extent while regaining physical competence faster. STUDY DESIGN/MATERIALS AND METHODS: Muscle crush injury was performed on 30 female Wistar rats using direct pressure for 10 minutes on the gastrocnemius muscle in both left and right hindlimbs. Immediately after the injury, only the left hindlimb were irradiated for 16 minutes (with 780 nm laser with a power of 250 mW, the energy at the target was 240 J, and the fluence was 1019 J/cm2 ) for 1, 3, or 7 consecutive days, and sacrificed accordingly. During the follow-up period, 1, 3, or 7 days, both gastrocnemius muscles (of the treated and untreated hindlimbs) were evaluated for electrophysiology and functionality. RESULTS: The laser photobiomodulation treatment showed a significant electrophysiological and functional recovery of the gastrocnemius muscle during the first 3 days after injury, in comparison with the untreated hindlimb. CONCLUSIONS: These preliminary results are promising, showing a significant effect of the laser photobiomodulation treatment during the first 3 days after the induction of the muscle crush injury, which is the most critical period in the clinical aspect. These findings suggest a therapeutic approach, which may help restore the muscle after crush injury.

Photobiomodulation in Neuroscience: A Summary of Personal Experience.

OBJECTIVE: This review summarizes personal experience with laser photobiomodulation and its potentials for the treatment of peripheral and central nerve system injuries. METHODS AND RESULTS: Laser photobiomodulation was shown to induce nerve cell activation, have a positive effect on metabolism of the nerve cells, and to stimulate nerve sprouting processes. Studies investigating the effects of laser photobiomodulation on injured peripheral nerves in rats reported immediate protective effects which increase the functional activity of the nerve, decrease or prevent scar tissue formation at the injured site, prevent or decrease degeneration in corresponding motor neurons of the spinal cord, and significantly increase axonal growth and myelinization. A direct application of laser on the spinal cord had a positive impact on the corresponding injured peripheral nerve and promoted recovery. A 780-nm laser phototherapy was applied following peripheral nerve reconstruction using a guiding nerve tube. Results showed myelinated axons crossing through the nerve tube and the continuation of axonal sprouting through the tube toward the distal part of the nerve. In a double-blind, placebo-controlled randomized pilot clinical trial in patients with incomplete stable long-term peripheral nerve injury (PNI), 780-nm laser irradiation progressively improved peripheral nerve function and led to substantial functional recovery. Muscle atrophy represents a major challenge in restorative medicine. Laser phototherapy was shown to increase biochemical activity and improve morphological recovery in muscle and, thus, could have a direct therapeutic application, especially during progressive muscle atrophy resulting from PNI. The effectiveness of composite implants of cultured embryonal nerve cells and the role of laser irradiation on regeneration and repair of the completely transected rat spinal cord were examined. Results suggested that laser photobiomodulation treatment accelerates the axonal growth. CONCLUSIONS: The significance of the performed experimental and clinical studies is in the provision of new laser technology in field of cell therapy and its therapeutic value for peripheral nerve and spinal cord injuries. Additional well-designed clinical studies are needed to evaluate the effectiveness and role of laser photobiomodulation treatment in a clinical setting.

Photobiomodulation Triple Treatment in Peripheral Nerve Injury: Nerve and Muscle Response.

BACKGROUND: Muscle preservation or decrease in muscle degeneration and progressive atrophy are major challenges in patients with severe peripheral nerve injury (PNI). Considerable interest exists in the potential therapeutic value of laser phototherapy (photobiomodulation) for restoring denervated muscle atrophy and for enhancing regeneration of severely injured peripheral nerves. As previously published, the laser phototherapy has a protective and immediate effect in PNI. Laser phototherapy in the early stages of muscle atrophy may preserve the denervated muscle by maintaining creatinine kinase (CK) activity and the amount of acetylcholine receptor (AChR). OBJECTIVE AND METHODS: In the present study, the effectiveness of triple treatment laser phototherapy, namely, applied simultaneously at three areas: injured area of the peripheral nerve, corresponding segments of the spinal cord, and corresponding denervated muscle (triple treatment), was evaluated for the treatment of incomplete PNI in rats with the ultimate goal of achieving improved limb function. RESULTS: Forty-five days after the sciatic nerve insult, all rats regained normal walking (functional sciatic index values returned to baseline); however, the long laser irradiation (7 min) group presented the fastest recovery as opposed to short laser irradiation (3 min). A histological evaluation of the nerves revealed that long laser irradiation led to a higher amount of neuronal fibers that were larger than 4 µm (543 ± 76.8, p < 0.01) than short irradiation (283 ± 35.36). A histological evaluation of muscular atrophy showed that long laser irradiation evolved with significantly less muscle atrophy (8.06% ± 1.23%, p < 0.05) than short irradiation (24.44% ± 7.26%). CONCLUSIONS: The present study and our previous investigations showed that the laser phototherapy increases biochemical activity and improves morphological recovery in muscle and, thus, could have direct therapeutic applications on muscle, especially during progressive atrophy resulting from PNI.

Phototherapy and nerve injury: focus on muscle response.

Preservation of biochemical processes in muscles is a major challenge in patients with severe peripheral nerve injury. In this chapter, we address the effects of laser irradiation and biochemical transformation in muscle, using in vitro and in vivo experimental models. The authors attempt to explain the possible mechanism of laser phototherapy applied on skeletal muscle on the basis of literature review and new results. A detailed knowledge of the evolution of endplates acetylcholine receptors and creatine kinase activity following laser irradiation can help to understand the therapeutic effect of laser phototherapy on muscle. This study showed that the laser phototherapy increases biochemical activity in intact muscle and thus could have direct therapeutic applications on muscle, especially during progressive atrophy resulting from peripheral nerve injury.

Protective effect of laser phototherapy on acetylcholine receptors and creatine kinase activity in denervated muscle.

OBJECTIVE: This study was designed to assess the status of skeletal muscles after laser treatment during long-term denervation processes, by investigating changes in the level of acetylcholine receptors (AChR) and creatine kinase (CK) activity in the denervated gastrocnemius muscle of the rat. BACKGROUND DATA: Progressive muscle atrophy is common in patients with severe peripheral nerve injury. Denervated muscles can account for significant differences in the extent of AChR and CK activity during the denervation period. MATERIAL AND METHODS: The study was conducted on 96 rats: 48 that received laser treatment and 48 untreated controls. The gastrocnemius muscle was denervated by removing a 10 mm segment of the sciatic nerve. Low power laser irradiation was delivered transcutaneously to the right gastrocnemius muscle (HeNe continuous wave [CW] laser, 632.8 nm, 35 mW, 30 min) for 14 consecutive days. Under general anesthesia, the rats were euthanized at seven time points: day 7 (n=10), day 14 (n=10), day 21 (n=10), day 30 (n=5), day 60 (n=4), day 120 (n=5), and day 210 (n=4), with and without laser treatment, respectively. AChR was quantified by the (125)I-α-bungarotoxin. CK activity was measured by a specific spectrophotometric method. RESULTS: Laser treatment had a significant therapeutic effect on the denervated muscle during the first 21 days for AChR and the first 30 days for CK activity. CONCLUSIONS: In the early stages of muscle atrophy, laser phototherapy may preserve the denervated muscle by maintaining CK activity and the amount of AChR.

Chapter 25: Phototherapy in peripheral nerve injury: effects on muscle preservation and nerve regeneration.

Posttraumatic nerve repair and prevention of muscle atrophy represent a major challenge of restorative medicine. Considerable interest exists in the potential therapeutic value of laser phototherapy for restoring or temporarily preventing denervated muscle atrophy as well as enhancing regeneration of severely injured peripheral nerves. Low-power laser irradiation (laser phototherapy) was applied for treatment of rat denervated muscle in order to estimate biochemical transformation on cellular and tissue levels, as well as on rat sciatic nerve model after crush injury, direct or side-to-end anastomosis, and neurotube reconstruction. Nerve cells' growth and axonal sprouting were investigated in embryonic rat brain cultures. The animal outcome allowed clinical double-blind, placebo-controlled randomized study that measured the effectiveness of 780-nm laser phototherapy on patients suffering from incomplete peripheral nerve injuries for 6 months up to several years. In denervated muscles, animal study suggests that the function of denervated muscles can be partially preserved by temporary prevention of denervation-induced biochemical changes. The function of denervated muscles can be restored, not completely but to a very substantial degree, by laser treatment initiated at the earliest possible stage post injury. In peripheral nerve injury, laser phototherapy has an immediate protective effect. It maintains functional activity of the injured nerve for a long period, decreases scar tissue formation at the injury site, decreases degeneration in corresponding motor neurons of the spinal cord, and significantly increases axonal growth and myelinization. In cell cultures, laser irradiation accelerates migration, nerve cell growth, and fiber sprouting. In a pilot, clinical, double-blind, placebo-controlled randomized study in patients with incomplete long-term peripheral nerve injury, 780-nm laser irradiation can progressively improve peripheral nerve function, which leads to significant functional recovery. A 780-nm laser phototherapy temporarily preserves the function of a denervated muscle, and accelerates and enhances axonal growth and regeneration after peripheral nerve injury or reconstructive procedures. Laser activation of nerve cells, their growth, and axonal sprouting can be considered as potential treatment for neural injury. Animal and clinical studies show the promoting action of phototherapy on peripheral nerve regeneration, which makes it possible to suggest that the time for broader clinical trials has come.

Increase of neuronal sprouting and migration using 780 nm laser phototherapy as procedure for cell therapy.

BACKGROUND AND OBJECTIVES: The present study focuses on the effect of 780 nm laser irradiation on the growth of embryonic rat brain cultures embedded in NVR-Gel (cross-linked hyaluronic acid with adhesive molecule laminin and several growth factors). Dissociated neuronal cells were first grown in suspension attached to cylindrical microcarriers (MCs). The formed floating cell-MC aggregates were subsequently transferred into stationary cultures in gel and then laser treated. The response of neuronal growth following laser irradiation was investigated. MATERIALS AND METHODS: Whole brains were dissected from 16 days Sprague-Dawley rat embryos. Cells were mechanically dissociated, using narrow pipettes, and seeded on positively charged cylindrical MCs. After 4-14 days in suspension, the formed floating cell-MC aggregates were seeded as stationary cultures in NVR-Gel. Single cell-MC aggregates were either irradiated with near-infrared 780 nm laser beam for 1, 4, or 7 minutes, or cultured without irradiation. Laser powers were 10, 30, 50, 110, 160, 200, and 250 mW. RESULTS: 780 nm laser irradiation accelerated fiber sprouting and neuronal cell migration from the aggregates. Furthermore, unlike control cultures, the irradiated cultures (mainly after 1 minute irradiation of 50 mW) were already established after a short time of cultivation. They contained a much higher number of large size neurons (P<0.01), which formed dense branched interconnected networks of thick neuronal fibers. CONCLUSIONS: 780 nm laser phototherapy of embryonic rat brain cultures embedded in hyaluronic acid-laminin gel and attached to positively charged cylindrical MCs, stimulated migration and fiber sprouting of neuronal cells aggregates, developed large size neurons with dense branched interconnected network of neuronal fibers and, therefore, can be considered as potential procedure for cell therapy of neuronal injury or disease.

Phototherapy in peripheral nerve regeneration: From basic science to clinical study.

OBJECT: This review summarizes the continuous study of low-power laser radiation treatment of a severely injured peripheral nerve. Laser phototherapy was applied as a supportive factor for accelerating and enhancing axonal growth and regeneration after injury or a reconstructive peripheral nerve procedure. In nerve cell cultures, laser phototherapy was used to stimulate activation of nerve cells. METHODS: Low-power laser radiation was used for treatment of peripheral nerve injury using a rat sciatic nerve model after crush injury, neurorrhaphy, or neurotube reconstruction. Nerve cell growth and axonal sprouting were investigated using laser phototherapy on embryonic rat brain cultures. The outcome in animal studies facilitated a clinical double-blind, placebo-controlled, randomized study that measured the effectiveness of 780-nm laser phototherapy on patients suffering from incomplete peripheral nerve injuries for 6 months to several years. RESULTS: Animal studies showed that laser phototherapy has an immediate protective effect, maintains functional activity of the injured nerve, decreases scar tissue formation at the injury site, decreases degeneration in corresponding motor neurons of the spinal cord, and significantly increases axonal growth and myelinization. In cell cultures, laser irradiation accelerates migration, nerve cell growth, and fiber sprouting. A pilot clinical double-blind, placebocontrolled, randomized study showed that in patients with incomplete long-term peripheral nerve injury, 780-nm laser radiation can progressively improve peripheral nerve function, which leads to significant functional recovery. CONCLUSIONS: Using 780-nm laser phototherapy accelerates and enhances axonal growth and regeneration after injury or a reconstructive peripheral nerve procedure. Laser activation of nerve cells, their growth, and axonal sprouting can be considered as potential treatment of neuronal injury. Animal and clinical studies show the promoting action of phototherapy on peripheral nerve regeneration, making it possible to suggest that the time for broader clinical trials has arrived.

Laser phototherapy (780 nm), a new modality in treatment of long-term incomplete peripheral nerve injury: a randomized double-blind placebo-controlled study.

OBJECTIVE: The authors conducted this pilot study to prospectively investigate the effectiveness of low-power laser irradiation (780 nm) in the treatment of patients suffering from incomplete peripheral nerve and brachial plexus injuries for 6 months up to several years. BACKGROUND DATA: Injury of a major nerve trunk frequently results in considerable disability associated with loss of sensory and motor functions. Spontaneous recovery of long-term severe incomplete peripheral nerve injury is often unsatisfactory. METHODS: A randomized, double-blind, placebo-controlled trial was performed on 18 patients who were randomly assigned placebo (non-active light: diffused LED lamp) or low-power laser irradiation (wavelength, 780 nm; power, 250 mW). Twenty-one consecutive daily sessions of laser or placebo irradiation were applied transcutaneously for 3 h to the injured peripheral nerve (energy density, 450 J/mm(2)) and for 2 h to the corresponding segments of the spinal cord (energy density, 300 J/mm(2)). Clinical and electrophysiological assessments were done at baseline, at the end of the 21 days of treatment, and 3 and 6 months thereafter. RESULTS: The laser-irradiated and placebo groups were in clinically similar conditions at baseline. The analysis of motor function during the 6-month follow-up period compared to baseline showed statistically significant improvement (p = 0.0001) in the laser-treated group compared to the placebo group. No statistically significant difference was found in sensory function. Electrophysiological analysis also showed statistically significant improvement in recruitment of voluntary muscle activity in the laser-irradiated group (p = 0.006), compared to the placebo group. CONCLUSION: This pilot study suggests that in patients with long-term peripheral nerve injury noninvasive 780-nm laser phototherapy can progressively improve nerve function, which leads to significant functional recovery.

Efficacy of 780-nm laser phototherapy on peripheral nerve regeneration after neurotube reconstruction procedure (double-blind randomized study).

OBJECTIVE: This pilot double-blind randomized study evaluated the efficacy of 780-nm laser phototherapy on the acceleration of axonal growth and regeneration after peripheral nerve reconstruction by polyglycolic acid (PGA) neurotube. BACKGROUND DATA: The use of a guiding tube for the reconstruction of segmental loss of injured peripheral nerve has some advantages over the regular nerve grafting procedure. Experimental studies have shown that laser phototherapy is effective in influencing nerve regeneration. METHODS: The right sciatic nerve was transected, and a 0.5-cm nerve segment was removed in 20 rats. A neurotube was placed between the proximal and the distal parts of the nerve for reconnection of nerve defect. Ten of 20 rats received post-operative, transcutaneous, 200-mW, 780-nm laser irradiation for 14 consecutive days to the corresponding segments of the spinal cord (15 min) and to the reconstructed nerve (15 min). RESULTS: At 3 months after surgery, positive somato-sensory evoked responses were found in 70% of the irradiated rats (p = 0.015), compared to 30% of the non-irradiated rats. The Sciatic Functional Index in the irradiated group was higher than in the non-irradiated group (p < 0.05). Morphologically, the nerves were completely reconnected in both groups, but the laser-treated group showed an increased total number of myelinated axons. CONCLUSION: The results of this study suggest that postoperative 780-nm laser phototherapy enhances the regenerative process of the peripheral nerve after reconnection of the nerve defect using a PGA neurotube.

Photoengineering of neural tissue repair processes in peripheral nerves and the spinal cord: research development with clinical applications.

The purpose of the present paper is to provide our data on the effects of phototherapy on peripheral nerve recovery. The aim is to call attention to an issue that still requires much research to elucidate the biological mechanisms through which phototherapy exerts its effects on nerve tissue, and to provide clinicians with the basis for planning clinical trials on the use of phototherapy for enhancing post-traumatic nerve regeneration.

Phototherapy for enhancing peripheral nerve repair: a review of the literature.

Posttraumatic nerve repair continues to be a major challenge of restorative medicine. Although enormous progress has been made in surgical techniques over the past three decades, functional recovery after a severe lesion of a major nerve trunk is often incomplete and sometimes unsatisfactory. It is thus particularly important to investigate clinical protocols to enhance nerve regeneration after surgical nerve repair. The present article reviews literature on one possible rehabilitation approach for enhancing nerve recovery, namely phototherapy. The number of experimental studies that have reported on the promoting action of phototherapy on peripheral nerve regeneration, together with the few known side effects related to the use of this type of physical therapy, make it possible to suggest that the time for broader clinical trials has come.

Phototherapy promotes regeneration and functional recovery of injured peripheral nerve.

Numerous attempts have been made to enhance and/or accelerate the recovery of injured peripheral nerves. One of the methods studied is the use of phototherapy (low power laser or light irradiation) to enhance recovery of the injured peripheral nerve. A critical analysis of the literature on the employment of phototherapy for the enhancement of the regeneration process of the rat facial and sciatic nerve (after crush injury or transection followed by surgical reconstruction) is provided, together with the description of some of the most suitable basic biological mechanisms through which laser radiation exerts its action on peripheral nerve regeneration.