Abnormal lymphatic system function in patients with chronic neck and shoulder pain: neuroimaging evidence from DTI-ALPS

Objective Chronic neck and shoulder pain (CNSP) is frequently associated with structural and functional brain damage that progressively worsens over time. The glymphatic system (GS), a gel-like extracellular fluid in the brain, plays a crucial role in clearing waste products and maintaining interstitial fluid homeostasis. However, its relationship with CNSP remains unclear. This study employed diffusion tensor imaging along perivascular spaces (DTI-ALPS) to investigate functional changes in the lymphatic system among patients with chronic neck and shoulder pain, while exploring potential correlations with clinical outcomes. Methods This study enrolled 20 patients with CNSP and 20 healthy controls (HCs). All participants underwent standardized scans using a 3.0T MRI scanner. By calculating the bilateral DTI-ALPS indices of the two groups, we compared the functional status of GS between the groups and further established its correlation with clinical indicators. Results Following a permutation test (10,000), the DTI-ALPS index in the left cerebral hemisphere of the CNSP group was significantly lower than that in the HCs group ( P = 0.0413). Within the CNSP group itself, the left hemisphere showed a more pronounced reduction compared to the right side ( P = 0.0012). Partial correlation analysis revealed that after excluding disease duration as a variable, VAS scores demonstrated a significant correlation with left hemisphere DTI-ALPS index ( r = −0.651, P = 0.003). When VAS was excluded from the analysis, disease duration showed a statistically significant association with left hemisphere DTI-ALPS index ( r = −0.727, P < 0.001). Conclusion Our findings indicate that CNSP may lead to abnormal GS function in the left hemisphere as the disease duration prolongs and pain intensity increases.