Altered body representation in chronic non-specific low back pain: a testable framework linking body-schema-related...

Low back pain is a leading contributor to disability worldwide; in chronic non-specific low back pain (CNSLBP), the processes sustaining pain and disability in the absence of identifiable structural pathology remain incompletely understood. Three partially overlapping research lines have documented altered body representation, corticomotor alterations of trunk musculature, and altered pain processing in this population, but these domains have rarely been measured concurrently within the same cohort. This Hypothesis and Theory article proposes that, once the measurement structure of candidate indicators has been established, body-representation-related measures will provide reproducible incremental explanatory information for prespecified corticomotor and pain-processing outcomes beyond relevant clinical, psychological, and nociplastic-feature variables. Within this multidimensional domain, body-schema-related sensorimotor disturbance is examined as one candidate interacting mechanism that may be coupled to corticomotor and pain-processing abnormalities; it is not assumed to be a privileged or causally primary organizer. Currently available assessments do not directly measure body schema but rely on indirect and theoretically heterogeneous proxies, including self-reported back perception, tactile acuity, and implicit laterality or motor-imagery processing. We synthesize evidence from neuroimaging, transcranial magnetic stimulation, psychophysical pain assessment, and behavioral paradigms, using predictive coding as a heuristic framework for deriving testable predictions concerning trunk-state estimation, motor regulation, and pain-processing indices. The proposed framework suggests that altered trunk-state representation may interact with altered motor regulation and altered pain processing in a mutually reinforcing loop. However, the directional architecture remains untested; models in which altered pain processing, corticomotor alteration, or a shared upstream process contributes to representational disturbance remain viable. The framework specifies a construct-validity prerequisite and four predictions concerning incremental cross-domain association, nociplastic-feature enrichment, intervention-linked cross-domain change, and temporal ordering and model comparison. Current evidence supports several measurable body-representation-related phenomena associated with clinical features in CNSLBP; however, the incremental explanatory value of the broader domain and the mechanistic independence of the narrower body-schema-related component remain empirical questions requiring discriminant, longitudinal, and experimental validation.