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

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>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.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>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.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>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.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>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.</jats:p></jats:sec>

Stimulation Effect of Low Level Laser Therapy on Sciatic Nerve Regeneration in Rat

“…In the late 1970s, it was reported that laser energy affects the regeneration of traumatically injured peripheral nerves. 13 However, most of the findings on the positive effects of phototherapy on peripheral nerve regeneration have been reported only since the late 1980s, 14,15 in 1987, Rochkind et al applied low-energy He-Ne laser irradiation (LELI, 632.8 nm, 10 J/cm 2 , continuous) on both intact and severely injured peripheral nerves in rats for 20 consecutive days and reported promising electrophysiological and morphological effects. 16 This was followed by a report on decrease in formation of scar tissue at the site of injury 17 and acceleration of the regeneration process of severely injured sciatic nerve and spinal cord.…”

“…[26][27][28] Most reports on the effect of LLLT on PNS injury are in cases of axonotmesis. [13][14][15][18][19][20][21]25,[29][30][31][32] However, promising results have been obtained in severe cases of neurotmesis when LLLT is used in combination with or Gore-Tex tubes. 27 The cutaneous branch consisted of 400 myelinated and 1800 unmyelinated afferent axons.…”

Effect of 850 nm He-Ne Laser Therapy on Nerve Conduction and Foot Planter Pressures Distribution of Painful Diabetic Neuropathy: A Randomized Controlled Trial

“…Prathap et al [26] found that LLLT of 3 and 4 j/cm 2 was effective for regeneration of both motor and sensory nerve conduction velocity of experimentally induced diabetic neuropathy as compared with control group. Also Rochkind et al [27] found that 15 min application of laser therapy transcutaneously to both the site of nerve injury and to the corresponding segments of the spinal cord improves function recovery and recruitment of voluntary muscle activity. Other studies concluded that laser irradiation allows higher metabolism for nerve, prevents degeneration of motor cell, induces proliferation of Schwann cell, allows and increases myelinization and axon regeneration [13,28,29].…”

Influence of low level laser therapy versus pulsed electromagnetic field on diabetic peripheral neuropathy

“…Earlier research findings suggested that LLL treatment appears to enhance re innervation of target tissues subsequent to nerve injury [41]. Rochkind [42] found that laser improves function recovery and recruitment of voluntary muscle activity through application transcutaneously to the site of nerve injury (15 min) and to the corresponding segments of the spinal cord (15 min).…”