Low-Level Laser Therapy in Stroke and Central Nervous System

Ying-Ying Huang Wellman Center for Photomedicine, Massachusetts General Hospital, Boston MA; Department of Dermatology, Harvard Medical School, Boston MA Aesthetic Plastic Laser Center, Guangxi Medical University, Nanning, Guangxi, P. R. ChinaMichael R Hamblin Wellman Center for Photomedicine, Massachusetts General Hospital, Boston MA Department of Dermatology, Harvard Medical School, Boston MA Harvard-MIT Division of Health Sciences and Technology, Cambridge MALuis De Taboada PhotoThera Inc, Carlsbad, CA27.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 718 27.2 Photobiology of Low-Level Laser Therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 718 27.3 LLLT Effects on Nerves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 719 27.4 Human Skull Transmission Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 720 27.5 The Problem of Stroke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 721 27.6 TLT for Stroke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 724 27.7 LLLT for CNS Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 727 27.8 LLLT for Neurodegenerative Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 730 27.9 LLLT for Psychiatric Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 731 27.10Conclusions and Future Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 731References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 733Low-level laser/light therapy (LLLT) for neurological disorders in the central nervous system (CNS) is currently an experimental concept. The broad goals for clinical utilization are the prevention and/or repair of damage, relief of symptoms, slowing of disease progression, and correction of genetic abnormalities. Experimental studies have tested and continue to test these goals by investigating LLLT in animal models of diseases and injuries that affect the brain and spinal cord. Successful clinical trials have been carried out of transcranial laser therapy for stroke. Discoveries concerning the molecular basis of various neurological diseases, combined with advances that have been made in understanding the molecular and cellular mechanisms in LLLT, both in vitro and in vivo, have allowed rational light-based therapeutic approaches for a wide variety of CNS disorders to be investigated. Limitations in knowledge are still apparent, such as the optimal wavelength, light source, doses, pulsed or CW, polarization state, treatment timing, and repetition frequency. Collaborative efforts between clinicians and basic researchers will likely increase the usage and understanding of effective laser-based therapies in the CNS.