Association of brain cortical changes with efficacy of treatment in patients with chronic neck and shoulder pain: a longitudinal surface-based morphometry study.

Objective: Studies have shown that the pathophysiological mechanisms of Chronic neck and shoulder pain (CNSP) involve not only local spinal and neural abnormalities but also abnormal brain cortical structures related to pain modulation. However, it remains unclear how these cortical alterations may influence efficacy of treatment. Materials and methods: 31 CNSP patients and 30 age- and gender-matched healthy controls (HCs) underwent 3D high-resolution structural magnetic resonance imaging (MRI) scans. The CNSP patients underwent a second MRI scan 3 months after receiving minimally invasive interventional treatment. The longitudinal changes in cortical thickness (CT), fractal dimension (FD), gyrification index (GI), and sulcal depth (SD) were studied before and after treatment in the CNSP patients, and conducted partial correlation analysis with treatment efficacy. Results: Compared to healthy controls, CNSP patients at baseline exhibited significant reduced cortical thickness (CT) in the bilateral precentral gyrus, superior frontal gyrus, lingual gyrus, left paracentral lobule, fusiform gyrus, superior temporal gyrus, supramarginal gyrus, and right precuneus. Deeper sulcal depth (SD) was observed in the bilateral central sulcus, anterior and posterior cingulate cortices, insula, lateral orbitofrontal cortex (OFC), and left dorsolateral prefrontal cortex (DLPFC). Additionally, an increased Gyrification Index (GI) was found in the bilateral lingual gyrus, left lateral OFC, anterior/posterior cingulate cortices, and right medial OFC. Three months after minimally invasive intervention, these morphological abnormalities showed widespread normalization. Correlation analyses revealed that higher baseline CT in the left precentral gyrus and paracentral lobule, lower baseline SD in the left cingulate cortex and central sulcus, and higher baseline GI in the right medial OFC were significant predictors of greater pain relief. Furthermore, the longitudinal restoration of CT in the left precentral gyrus and SD normalization in the left DLPFC and cingulate cortex were positively correlated with the reduction in VAS scores. Conclusion: This study identifies specific morphological alterations characterized by cortical thinning and increased sulcal depth in the sensorimotor cortex (precentral gyrus, paracentral lobule, central sulcus) and the pain modulation network (cingulate cortex, DLPFC, OFC) as key biomarkers for CNSP. The findings demonstrate that baseline structural integrity in these specific regions serves as a robust predictor of treatment efficacy. Moreover, the longitudinal structural recovery paralleling pain relief confirms the reversible nature of maladaptive neuroplasticity, highlighting CT in the precentral gyrus and SD in the DLPFC as critical indicators for evaluating chronic pain interventions.