Application of Shear Wave Elastography in Assessing Peripheral Neuropathy in Parkinson’s Disease

Background/Objectives: Parkinson’s disease (PD) is a prevalent neurodegenerative disorder, and its comorbid peripheral neuropathy (PN) severely worsens patient prognosis. The diagnostic gold standard, nerve electrophysiological examination, has critical limitations, including invasiveness. This study aimed to explore the diagnostic value of high-frequency ultrasound combined with shear wave elastography (SWE) for PD-associated PN. Methods: Intra- and inter-observer reproducibility of ultrasound parameters (cross-sectional area [CSA], shear wave velocity [SWV]) of the median and common peroneal nerves was validated in 30 PD patients. A case–control study was conducted in 40 PD patients (stratified into PD-alone and PD-PN groups via the electrophysiological gold standard) and 40 healthy controls. Correlation analysis, logistic regression, and receiver operating characteristic (ROC) curve analysis were performed to assess diagnostic efficacy. Results: All measured parameters showed good reproducibility (intraclass correlation coefficient [ICC] > 0.855). Median nerve longitudinal SWV and common peroneal nerve SWV increased sequentially across the control, PD-alone, and PD-PN groups (after age adjustment using analysis of covariance (ANCOVA), p < 0.001), and showed weak-to-moderate statistically significant correlations with median nerve motor conduction latencies after Bonferroni correction for multiple comparisons. Age and common peroneal nerve SWV were identified as independent risk factors for PD-PN, while median nerve longitudinal SWV showed a positive but non-significant association in the multivariable model. A combined model incorporating age, median nerve longitudinal SWV, and common peroneal nerve SWV achieved an area under the ROC curve (AUC) of 0.938 (sensitivity 93.75%, specificity 91.67%; bootstrap-corrected AUC = 0.906). Conclusions: SWE-derived SWV has favorable diagnostic value for PD-associated PN with good reproducibility. The combination of age and multi-nerve SWV further improves diagnostic efficiency, providing a reliable non-invasive imaging biomarker for early PD-PN diagnosis. However, given the observational design and significant age imbalance between groups, residual confounding cannot be fully excluded, and prospective studies with age-matched cohorts are needed for definitive confirmation.