Transcranial Yellow, Red, and Infrared Laser and LED Stimulation: Changes of Vascular Parameters in a Chick Embryo Model

Abstract

Background: The use of transcranial laser or light-emitting diode (LED) therapy in the treatment of different neurological diseases is attracting increasing attention. The main goal of this study was to investigate different kinds of scientifically and commercially available laser (yellow, red, and infrared) and LED stimulation systems for the first time using a chick embryo model under a fixed human cadaver (scalp and/or skull) and without this anatomical preparation. Methods: In the present study, the extra-embryonic vasculature of a 1-week-old chick embryo chorioallantoic membrane (CAM) was investigated. For stimulation, four different systems were used (infrared LED and yellow, red, and infrared laser). Four measurement periods were compared: before stimulation, immediately after stimulation onset, immediately after the 10-min stimulation was turned off, and 6 min after stimulation had ended. Special image processing programs developed at the Beijing University of Science and Technology were used for data analysis. Results: The different kinds of laser induced different effects, e.g. the direct stimulation with yellow laser led to initial vasoconstriction (-17%), whereas yellow laser stimulation through a human skull resulted in an increase in blood volume. These effects could only be observed after mathematical processing of the images. Conclusion: After intensive basic research (e.g. CAM model), transcranial laser stimulation may open up new therapies for lifestyle-related diseases such as stroke, dementia, Alzheimer's or possibly Parkinson's disease.

Which wavelength is optimal for transcranial low‐level laser stimulation?

“…Based on the investigation of the peer‐reviewed literatures on the wavelength selection for transcranial LLLT , we found that there were mainly four wavelengths used in LLLT community, no matter the research or clinical field. Litscher recently extended mice experimental study to human skull and scalp‐skull‐chick embryo head model study on the wavelength selection, however, human cerebral tissue and cerebrospinal fluid was still unconcerned . Therefore, there was no study on the whole human head to address the issue about the optimal selection on all candidate wavelengths in LLLT.…”

“…For example, we are looking forward to perform the neurobehavioral test on 1064 nm photon transcranial stimulation, and test if 1064 nm acted the same with 980 nm at the initial stage. Then, other wavelengths (eg, 589 nm as suggested in Litscher's newly studies ) and other illumination parameters are expected to get both the quantitative photon penetration analysis and neurobehavioral performance evaluation results in transcranial LLLT experimental study. After further and fully testing this hypothesis, it is not hard to foresee the online and precise optimization of LLLT illumination parameters with this resource‐saving, time‐saving, quantitative and 3D visible method.…”

“…Then, Litscher D and Litscher G extended the mice experimental study to human model experimental study. They compared the light transmittances in human skull among different wavelengths and modeled the human head with human scalp, skull and a chick embryo inside, and found that 810 nm resulted the best transmittance in skull and 589 nm resulted in an increase in blood volume . Considering that the chick embryo model is quite different to human cerebral cortex tissue and the absorption coefficient of the scalp at 589 nm was much stronger than those mostly used wavelengths , it probably led to sparse use of 589 nm in human transcranial LLLT.…”

Transcranial Laser Stimulation Research—A New Helmet and First Data from Near Infrared Spectroscopy

“…The prototype system is currently based on infrared lasers using a wavelength of 810 nm. This wavelength has recently been proven (July 2018) to be one of the best for transcranial laser stimulation [ 4 , 5 ]. The authors employed Monte Carlo modeling and a visible human phantom to compute the penetrated photon fluence distribution within the cerebral cortex.…”

Sino-Austrian High-Tech Acupuncture Network—Annual Report 2015

“…Gerhard Litscher from Medical University of Graz and comprises many partners from China. In the following, some milestones and publications [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ] from the year 2015 are listed chronologically:…”