Table 1. Low-Level Laser Therapy in SCI Studies .

Authors	Year	Laser Wavelength	Important Findings
Ando et al49	2013	808-nm	SCI rats treated with laser irradiation showed significantly higher functional scores. Locomotive function notably improved from day 10 post-injury in SCI rats treated with laser irradiation aligned parallel to the spinal column, compared to those treated with perpendicular linear polarization.
Paula et al40	2014	780-nm	Rats with spinal contusion treated with LLLT exhibited faster motor recovery. LLLT helped maintain urinary system function and preserved nerve tissue at the lesion site. Treatment showed significant inflammation control and an increase in nerve cells and connections. LLLT demonstrated positive effects on spinal cord recovery following moderate traumatic SCI.
Veronez et al46	2016	808-nm	Functional improvements, including enhanced tactile sensitivity, were observed after LLLT at higher fluence levels. LLLT reduced lesion volume and regulated inflammation by decreasing CD-68 protein expression. Higher doses of LLLT effectively promoted functional recovery and modulated the inflammatory response.
Janzadeh et al50	2017	660-nm	The combination of LLLT and Chondroitinase ABC (ChABC) significantly reduced cavity size and enhanced myelination and axon density around the lesion. Functional recovery was observed in animals treated with LLLT or ChABC alone, but the combination therapy yielded superior results.
Song et al41	2017	810-nm	LLLT increased the expression of anti-inflammatory cytokines IL-4 and IL-13. It demonstrated potential in reducing inflammation, modulating macrophage/microglia polarization, and enhancing neuronal survival. LLLT shows promise as an effective therapeutic option for clinical SCI treatment.
Kim et al51	2017	850-nm	LLLT significantly reduced TNF-α expression at the lesion epicenter and decreased iNOS expression in the caudal segment. It modulated inflammatory mediators, promoting motor function recovery after SCI. LLLT applied in the acute phase of SCI holds therapeutic potential for neuroprotection and restoring motor function.
Gong et al52	2018	810-nm	Laser treatment inhibited the tissue response to remyelination by suppressing CSPG expression. It also led to morphological improvements, including reduced glial scar formation and smaller cavity areas.
Mojarad et al45	2018	660-nm	LLLT resulted in a reduction of neuropathic pain following SCI. Two weeks of LLLT therapy was more effective in reducing neuropathic pain compared to one week of treatment. LLLT provided similar pain reduction to Methylprednisolone sodium succinate, without any associated side effects.
Zhang et al53	2019	810-nm	LLLT reduced the expression of M1 macrophage-specific markers and increased the expression of M2 macrophage-specific markers. Forward and reverse experiments confirmed that LLLT activates the PKA-CREB pathway in macrophages, promoting the secretion of neurotrophic factors and stimulating axon regeneration. Based on these findings, LLLT shows promise as an effective therapeutic approach for SCI, with potential clinical applications.
Poorhassan et al54	2021	810-nm	Immediate application of PBM (photobiomodulation) treatment after SCI offers neuroprotective effects by controlling oxidative stress and inflammation, preventing further damage. Photobiomodulation therapy also enhanced functional recovery and reduced cavity formation.
Wang et al55	2021	810-nm	PBM facilitated motor function recovery, inhibited the activation of neurotoxic microglia and astrocytes, alleviated neuroinflammation and tissue apoptosis, and increased the retention of neurons after SCI. Lcn2/JAK2-STAT3 crosstalk plays a role in activating neurotoxic microglia and astrocytes after SCI, and PBM can suppress this process.
Neshasteh-riz et al56	2022	660 nm	The number of treatment days is crucial for improving mobility, but the daily radiation dose plays a more significant role in pain relief.