JNNP: Microstructural plasticity of nociceptive pathways after spinal cord injury

The underlying pathophysiology of neuropathic pain (NP) after spinal cord injury is complex, involving “bottom-up” nociceptive information processing and “top-down” endogenous pain regulation.

So far, the increase and decrease of changes in the macrostructure (ie volume) of the brain and spinal cord are related to the occurrence of NP.

A multi-parameter mapping (MPM) protocol is used, which provides contrast sensitive to myelination and sensitive to iron content in tissues and blood (using effective transverse relaxation rate (R2*) 13) to track noxious pathway trajectories The complex relationship between upper structure and metabolic changes and its relationship with the existence and strength of NP.

After spinal cord injury, along the trajectory of ascending and descending noxious pathways, the difference in myelin sensitivity and iron sensitivity content is related to NP.

Statistical parameter diagram of the relationship between longitudinal relaxation (R1) and effective lateral relaxation rate (R2*) signal changes and the intensity of pain around the aqueduct and medulla oblongata

The neuronal matrix of the volume change caused by the injury is still not fully understood.

The decrease in volume is related to the decrease in myelin sensitivity R1, but it is also pain-specific because this decrease is not observed in pain-free patients.

This study reveals the microstructure characteristics of NP, which affect the key components of the ascending and descending nociceptive pathways, and its size is directly related to the strength of NP.