Development of the theragnostic optical system for a high-intensity laser therapy (HILT).

Recently, high-intensity laser therapy (HILT) has been introduced for muscle disorders, but its efficacy has not been confirmed due to the absence of quantitative assessments and treatment feedback data in real-time. In this clinical study, a theragnostic optical system comprised of a high-intensity laser and a non-invasive optical monitoring system was developed to assess spasticity. To avoid interference between the two different light sources, the therapeutic wavelength for HILT was selected at 808 nm, one of the isosbestic points. The monitoring system based on a near-infrared spectroscopy (NIRS) was utilized for measuring hemoglobin concentrations according to a modified Beer-Lambert's law. The transitory HILT effect was evaluated from patients experiencing spasticity after stroke. Our results showed the proportionate relationship between manual muscle testing grades and the HILT effect on hemiplegic patients. The developed system proved to be useful for the simultaneous assessment and treatment of spasticity, and it holds promise for real-time monitoring of hemoglobin concentrations during laser therapy.