Reference

Margaret A. Naeser, Ph.D., L.Ac.,1,2 and Michael R. Hamblin, Ph.D.3,4,5

Near-infrared (NIR) light passes readily through the scalp and skull and a small percentage of incident power density can arrive at the cortical surface in humans.1 The primary photoreceptors for red and NIR light are mitochondria, and cortical neurons are exceptionally rich in mitochondria.

It is likely that brain cells are ideally set up to respond to light therapy. The basic biochemical pathways activated by NIR light, e.g., increased adenosine-5’-triphosphate (ATP) production, and signaling pathways activated by reactive oxygen species, nitric oxide release, and increased cyclic adenosine monophosphate (AMP) all work together to produce beneficial effects in brains whose function has been compromised by ischemia, traumatic injury, or neurodegeneration. One of the main mechanisms of action of transcranial light therapy (TLT) is to prevent neurons from dying, when they have been subjected to some sort of hypoxic, traumatic, or toxic insult. This is probably because of light-mediated upregulation of cytoprotective gene products such as antioxidant enzymes, heat shock proteins, and anti-apoptotic proteins. Light therapy in vitro has been shown to protect neurons from death caused by methanol,2 cyanide or tetrodotoxin, 3 and amyloid beta peptide.4

Lapchak P A, Wei J, Zivin J A.

Transcranial infrared laser therapy improves clinical rating scores after embolic strokes in rabbits.

Stroke. 2004; 35 (8):1985-1988.

In this study the rabbit small clot embolic stroke model (RSCEM) was used to assess whether laser treatment (7.5 or 25 mW/cm²) altered clinical rating scores (behaviour) when given to rabbits beginning 1 to 24 hours post embolisation. Behavioural analysis was conducted from 24 hours to 21 days after embolisation, allowing for the determination of the effective stroke dose (P50) or clot amount (mg) that produces neurological deficits in 50% of the rabbits.

Using the RSCEM, a treatment is considered beneficial if it significantly increases the P50 compared with the control group. In the present study, the P50 value for controls were 0.97±0.19 mg to 1.10±0.17 mg; this was increased by 100% to 195% (P50=2.02±0.46 to 2.98±0.65 mg) if laser treatment was initiated up to 6 hours, but not 24 hours post embolisation (P50=1.23±0.15 mg). Laser treatment also produced a durable effect that was measurable 21 days after embolisation. Laser treatment (25 mW/cm²) did not affect the physiological variables that were measured. This study shows that laser treatment improved behavioural performance if initiated within 6 hours of an embolic stroke and the effect of laser treatment is durable.

Zhong Xi Yi Jie He Xue Bao. 2005 Mar;3(2):128-31.
Protective Effect Of Low-Level Laser Irradiation On Acupuncture Points Combined With Iontophoresis Against Focal Cerebral Ischemia-Reperfusion Injury In Rats

Dai JY, Ge LB, Zhou YL, Wang L.
Acupuncture Clinic, Institute of Qigong, Shanghai University of Traditional Chinese
Medicine, Shanghai 200030, China. djysh2002@yahoo.com.cn

OBJECTIVE: To investigate the effects of low-level laser irradiation on acupuncture points combined with iontophoresis against brain damage after middle cerebral artery occlusion (MCAO) in rats.
METHODS: Sixty-nine SD rats were randomly divided into five groups, including normal group, sham operation group, model group, electro-acupuncture group and low-level laser irradiation on acupuncture points combined with iontophoresis group (LLLI group). The cerebral ischemia-reperfusion (I/R) model was established by thread embolism of middle cerebral artery. The rats in the LLLI group, as well as the electroacupuncture group were given treatment as soon as the occlusion finished (0 hour) and 12, 24 hours after the occlusion. We observed the changes of neurological deficit scores and the body weight of the rats at different time. The activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) in the
ratos brain tissue were tested.

RESULTS: The neurological deficit score of the LLLI group was significantly lower than that of the model group. The body weight and the activity of SOD of the rats decreased slightly, and the content of MDA decreased significantly after the treatment.

CONCLUSION: The low-level laser irradiation on acupuncture points combined with iontophoresis can prevent focal cerebral ischemia-reperfusion injury. One of its mechanisms may be increasing the activity of SOD and decreasing the damage of the oxidation products to the body.

Vascular Low Level Laser Irradiation Therapy in Treatment of Brain Injury
WANG Yu ZHU Jing, et al (Department of Neurosurgery, Renji Hospital Affiliated to Shanghai Second Medical University, Shanghai Medical Centre for laser Research ,200001)
ACTA LASER BIOLOGY SINICA Vol. 8, No.2, 1999

Abstract: To evaluate the effect and mechanism of Vascular Low Level Laser Irradiation Therapy on brain injury. In this study thirty-eight SpragueDawley rats received Feeney's brain impact through a left lateral craniectomy under anesthesia. Control and treatment group are set up.
According to the time exposed to laser and irradiating postinjury, the treatment group is divided in four subgroups by design. Semiconductor laser was used with a power of 5mW to irridate straightly Rat's femur venous. The Y Water maze was used to assess cognitive performance. Superoxide dismutase(SOD) activity and the level of metabolic production of free radical MDA in Brain and erythrocyte were measured to determinate the level of free radical.

We find Vascular Low Level Laser Irradiation Therapy can improve posttraumatic memory deficits. SOD activity is higher in treatment groups than the control group meanwhile the level of MDA is lower. These findings suggest that Vascular Low Level Laser Irradiation produced a significant reduction in free radical's damage to the brain postinjury.

Infrared Laser Radiation In The Treatment Of Brain Injury Consequences
E.L. Macheret, A.O. Korkushko, T.N. Kalishchuk, M.N. Matyash
Medical Academy of Post-Diploma Education, Kiev, Ukraine

The examination of 198 patients aged 16-47 has revealed a high frequency of progressive pathologic states in a form of asthenia, vegeto-vascular dystonia, hypertensive, somatovegetative, vestibular syndroms. Taking into account thechanges in cortico-undercortical interrelations and expansion of pathologic process in hypothalamic area during the head trauma, we have developed effective treating methods by means of laseropuncture. Laser rays influence on acupuncture points (AP) leads to a convergence of the afferent messages upon the neurones
of spinal cord, reticular formation, thalamus, hypothalamus and brain cortex.

As a result of that adynamic balance between the inhibition and excitation processes in the structures of central nervous system leading vegetative function and endocrine secretion recovers. Use of infrared laser radiation is the most perspective. It docs not cause the direct photochemical reactions in biological tissues, but influences on physico-chemical structure of AP biomolecules. For laseropuncture we used an apparatus  with a wavelength of 0.89 nm. The work regime is impulsive-continuous with a modulation of frequency - from 0.1 to 1000 Hz. The middle power is up to 20 mW. The total time of the action for one sitting is till 20 min. The points
selections was carried out on the grounds of the methods of acupuncture diagnosis, imagesking out the dominant clinical syndromes and including points of vascular, vegetotroimages, sedative orientation. Our clinical results, which were confirmed by paraclinical methods (EEG, dopplerography) and methods of acupuncture diagnosis have shown a high effectiveness of this therapy decreasing the drugs load and having no contradictions