REVIEW OF 30-YEARS EXPERIENCE: LASER PHOTOTHERAPY IN NEUROSCIENCE AND NEUROSURGERY PART I -MUSCLE AND NERVE

Abstract

Background: Posttraumatic nerve repair and prevention of muscle atrophy represent a major challenge in restorative medicine. Considerable interest exists in the potential therapeutic value of laser phototherapy for restoring or temporary preventing denervated muscle atrophy as well as enhancing regeneration of severely injured peripheral nerve.
Methods:
I-Muscle and Peripheral Nerve Experimental Studies: low power laser irradiation (laser phototherapy) was applied for treatment of rat denervated muscle in order to estimate the biochemical transformation at cellular and tissue levels, as well as in a rat sciatic nerve model after crush injury, direct anastomosis and neurotube reconstruction.
II- Intraoperative Clinical Study: following microsurgical release and neurolysis the nerve was subjected to direct laser irradiation using fiber optics.
III- Clinical double-blind, placebo-controlled randomized study: based on the outcome of the animal trials, a clinical trial, which measured the effectiveness of 780-nm laser phototherapy on patients suffering from incomplete peripheral nerve injuries for 6 months up to several years, was designed.
Results: Experimental model of denervated muscle: the animal study suggested that function of denervated muscles was partially preserved by temporary prevention of denervation-induced biochemical changes. The function of denervated muscles was restored, not completely but to a very substantial degree, by laser treatment, initiated at the earliest possible stage post-injury.
Experimental peripheral nerve injury: laser phototherapy had an immediate protective effect, maintained functional activity of the injured nerve, decreased scar tissue formation at the injury site, decreased degeneration in corresponding motor neurons of the spinal cord and significantly increased axonal growth and myelinization.
Intraoperative clinical study: direct laser irradiation was shown to improve functional activity of the surgically treated nerve.
Clinical, double-blind, placebo-controlled randomized pilot study: in patients with incomplete long-term peripheral nerve injury, it was demonstrated that 780-nm laser irradiation progressively improved peripheral nerve function, which lead to significant functional recovery.
Conclusions: 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. Animal and clinical studies have both demonstrated the promoting action of phototherapy on peripheral nerve regeneration, which makes it possible to suggest that the time for broader clinical trials has come.