Inefficient default mode network hyperconnectivity characterizes chronic low back-related leg pains: a static and dynamic functional MRI study.

Pain-induced reorganization of the default mode network (DMN) exhibits distinct temporal signatures in the acute and chronic stages, yet the mechanistic interplay between static/dynamic network topology and pain chronicity remains unclear. In this study, we utilized both static and dynamic graph theory analyses to characterize DMN reconfiguration in 50 patients with low back-related leg pain (LBLP)--comprising 19 acute (aLBLP) and 31 chronic (cLBLP)--compared to 51 healthy controls. Chronic pain patients exhibited reduced global and nodal efficiency, accompanied by increased static functional connectivity (sFC) between the core and medial temporal lobe (MTL) subsystems. In contrast, acute pain patients demonstrated decreased temporal variability in dynamic functional connectivity (dFC), particularly between the core and MTL subsystems. Importantly, the alterations of static node topology properties in cLBLP correlated with pain intensity, whereas reduced dFC variability in aLBLP was predictive of neurological deficits, as assessed by the neurological assessments (LANSS). These findings suggest that chronic LBLP is associated with a paradoxical DMN state–inefficient hyperconnectivity–whereas acute pain disrupts temporal flexibility of DMN dynamics. This study advances our understanding of the dynamic interplay between DMN topology and pain chronicity, highlighting potential biomarkers for pain progression and neuroplasticity.