Transcranial low-level laser (light) therapy for stroke and traumatic brain injury in animal models

Low-level laser (light) therapy (LLLT) for traumatic events that cause brain damage is currently an experimental concept. The broad goals for clinical utilization are the prevention of brain damage, relief of symptoms, and stimulation of the repair process. Experimental studies have tested and continue to test these goals by investigating LLLT in animal models of stroke and traumatic brain injury (TBI). Animal studies of tLLLT for ischemic stroke have been summarized in this chapter. Studies by other groups on LLLT in mouse TBI models have been discussed. Four studies from our laboratory have been described. The first study looked at pulsed versus continuouswave (CW) laser irradiation in a controlled cortical impact (CCI)-TBI model and found pulsed 810 nm laser at 10 Hz to be superior. The second study looked at four different laser wavelengths (660, 730, 810, and 980 nm) in a closed-head TBI model; only 660 nm and 810 nm were effective. The third study looked at different treatment repetition regimens (1, 3, and 14 daily laser treatments). The last study used immunofluorescence techniques to showthat neurogenesis, brain-derived neurotrophic factor (BDNF), and synaptogenesis were upregulated after transcranial LLLT (tLLLT) for TBI. 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 central nervous system (CNS).