Striatal hyperechogenicity as an ultrasound imaging marker for prodromal X-linked dystonia-parkinsonism.

X-linked dystonia-parkinsonism (XDP) is a neurodegenerative genetic disorder with striatal pathology. We investigated 138 participants (61 patients with XDP, 19 non-manifesting carriers (NMC), and 58 healthy controls (HC)) with transcranial sonography (TCS) to determine the hyperechogenicity of the lentiform nucleus (LN+), the size of the substantia nigra, and the width of the lateral and third ventricles. LN+ was correlated with LN volume as measured by structural T1 imaging. Hexameric repeat number within the causative insertion was determined as a potential modifier. The prevalence of LN+ was higher in patients with XDP (81%) and in NMC (47%) compared to HC (20%). In NMC and XDP with LN+, the estimated age at onset was younger, and the repeat number was higher. There was no difference in the size of the substantia nigra nor in the width of the lateral ventricle. The width of the third ventricle was higher in patients with XDP and correlated with age at examination and disease duration. The MRI-derived LN volume was higher in HC than in NMC and XDP. There were no volume differences between LN+ and LN-. LN+ is observed more frequently in patients with XDP and even several years before symptom onset in NMC, particularly in those with a high genetic modifier burden. TCS might therefore be a helpful tool to identify persons at risk for a more imminent disease manifestation among the NMCs.