Photobiomodulation Therapy for Traumatic Spinal Cord Injury: Current Evidence and Future Directions.

Photobiomodulation (PBM) therapy (PBMT) to treat traumatic spinal cord (SC) injury (tSCI) is a growing area of research that could present a highly effective therapy for restoring function after tSCI. SC injuries (SCIs) are severe injuries that typically result in the loss of motor, sensory, and autonomic function, dramatically affecting the lives of patients and their families. SCI has two primary parts: the primary injury, which occurs immediately at the time of injury and is a result of mechanical forces on the SC, and the secondary injury, which occurs over the months following the initial incident and is primarily the result of biochemical damage. PBM is the process through which nonionizing light is absorbed by naturally occurring chromophores in the body and causes beneficial physiological changes without causing thermal damage. In the case of tSCI, PBMT seems to work through increasing energy availability enabling normalized cellular function after tSCI reducing the functional loss from the secondary injury. When applied to tSCI, PBMT has been shown to improve the functional recovery after a tSCI. These beneficial effects have been shown extensively in rodent models across multiple studies using a variety of parameters. In order to translate this promising therapy to the clinical setting, multiple steps need to be taken including understanding dosing, establishing efficacy and safety in large animal models and humans, and the development of a clinical-grade PBMT application system. This review seeks to provide a comprehensive overview of the progress that has been made in the field of PBMT for tSCI and the steps needed to translate this promising therapy to the clinical setting.