Diagnostic value of multi-regional multi-parameter transcranial sonography in differentiating Parkinson's disease from essential tremor.

OBJECTIVE: Differentiating Parkinson's disease (PD) from essential tremor (ET) remains challenging during early clinical stages. This study aimed to evaluate the diagnostic value of multi-regional multi-parameter transcranial sonography (TCS) in differentiating PD from ET. METHODS: A total of 80 PD patients and 23 ET patients admitted to the Department of Neurology between January 2024 and December 2025 were enrolled. All participants underwent comprehensive clinical assessment and standardized TCS examination. TCS parameters included bilateral substantia nigra (SN) hyperechogenicity area, bilateral midbrain area, third ventricle width, lentiform nucleus echogenicity, and brainstem raphe echogenicity. Age-adjusted binary logistic regression with bootstrap internal validation, Firth penalized-likelihood sensitivity analysis, and repeated cross-validation was performed. RESULTS: The bilateral SN hyperechogenicity total area (SNsum) was significantly larger in the PD group [median 0.30 (0.13-0.46) cm2] compared with the ET group [median 0 (0-0.25) cm2, p < 0.001]. Third ventricle width was significantly greater in PD patients (7.31 ± 1.73 mm vs. 5.57 ± 1.47 mm, p < 0.001). Age-adjusted logistic regression identified SNsum (OR = 69.023, p = 0.014) and third ventricle width (OR = 2.531, p = 0.001) as independent predictors. The combined predictor achieved an area under the ROC curve (AUC) of 0.848 (95% CI: 0.743-0.932), which was significantly higher than SNsum alone (AUC = 0.739; DeLong p = 0.022) and third ventricle width alone (AUC = 0.783; DeLong p = 0.034). At the optimal cutoff the combined predictor yielded a sensitivity of 75.0% (95% CI: 64.5-83.2%) and specificity of 82.6% (95% CI: 62.8-93.0%). Bootstrap-corrected AUC was 0.830, and the Firth penalized model and repeated cross-validation (AUC = 0.812) yielded concordant estimates. CONCLUSION: Multi-regional multi-parameter TCS may serve as a practical neuroimaging tool for differentiating PD from ET. The combined predictor provided moderate, internally validated discrimination and should be regarded as an exploratory tool requiring confirmation in larger, multicenter, prospective cohorts with external validation before clinical application.