Introduction: Wilson's disease (WD) is a hereditary disorder caused by ATP7B mutations resulting in systemic copper accumulation. WD may manifest as early-adulthood parkinsonism; and atypical cases may be difficult to distinguish from early-onset Parkinson's disease (EO-PD), a neurodegenerative disorder with onset ≤40 years of age. The aim of our study was to compare transcranial sonography (TCS)-magnetic resonance fusion imaging in WD and EO-PD and examine whether TCS can provide clinically useful information.
Methods: We examined 22 WD, 16 EO-PD, and 24 healthy control subjects. We measured echogenicity and determined presence of MRI signal changes in T2-weighted images in the substantia nigra (SN) and lentiform nucleus (NL). TCS with the capability of magnetic resonance fusion and Virtual Navigator was used. The echogenicity indices of SN and NL were processed using digital image analysis to eliminate subjective evaluation errors.
Results: Mean SN echogenicity index in EO-PD (39.8 ± 5.9 [SD]) was higher compared to WD (28.0 ± 4.6, p < 0.0001) and control subjects (28.8 ± 4.9, p < 0.0001). Mean NL echogenicity index was higher in WD (117.5 ± 37.0) compared to EO-PD (61.6 ± 5.4, p < 0.0001) and control subjects (54.9 ± 11.2, p < 0.0001). The SN hyperechogenicity had sensitivity 93.8%, and specificity 90.9%, while the NL hyperechogenicity had sensitivity 95.5% and specificity 93.8% for differentiation of WD and EO-PD. NL hyperechogenicity was more pronounced in WD subjects with putaminal MRI T2 hyperintensity (p < 0.05) but was also present in subjects without MRI abnormality.
Conclusions: There are distinct TCS findings in WD and EO-PD complementary to MRI that can be utilized as highly sensitive and specific biomarkers of these disorders.
Keywords: Copper; Early-onset Parkinson's disease; MRI; Transcranial sonography; Wilson's disease.
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