355 nm UV nanosecond laser-induced spinal cord nerve ablation: Spatiotemporal optimization towards high-precision...

Dorsal Root Entry Zoneotomy (DREZotomy) requires extreme surgical precision to eliminate hyperactive nociceptive pathways without compromising adjacent functional spinal tracts. Traditional electrothermal tools often induce unpredictable collateral thermal damage, posing significant risks of postoperative neurological deficits. In this study, we investigated the efficacy and underlying mechanisms of a 355 nm ultraviolet (UV) nanosecond laser for the highly controlled ablation of lipid-rich spinal cord nerve tissue. By systematically evaluating spatiotemporal parameters, we characterized the critical transitions between photochemical and photothermal tissue interactions. Morphological analyses demonstrated that while excessive energy densities trigger plasma-induced optical shielding, an optimal fluence window maximizes material removal efficiency. Furthermore, our temporal evaluation revealed that high-frequency pulse delivery exacerbates collateral thermal injury due to rapid heat accumulation when the inter-pulse interval falls below the tissue's inherent thermal relaxation time. Under optimized spatiotemporal conditions, Raman spectroscopy validated a predominant cold photochemical ablation regime, with the immediate residual tissue exhibiting remarkably preserved biomolecular signatures, including intact protein secondary structures and myelin lipids. Ultimately, this UV laser approach restricts the lateral zone of thermal damage to strictly less than 20 μm. These findings highlight the 355 nm nanosecond laser as a highly predictable, minimally invasive modality, offering a critical safety margin for delicate neurosurgical interventions.