The predictive power of transcranial sonography in movement disorders: a longitudinal cohort study.

Transcranial sonography (TCS) is a noninvasive, easily performed, and commonly available neuroimaging technique useful for the study of brain parenchyma in movement disorders. This tool has been increasingly used in the diagnosis of Parkinson's disease and atypical parkinsonism. The aim of the study was to evaluate the applicability of this technique as supportive tool in the early diagnosis of movement disorders. We performed TCS on 315 individuals which were diagnosed as healthy controls or affected by idiopathic Parkinson's disease, monogenetic subtypes of Parkinson's disease, atypical parkinsonism, and Dementia with Lewy bodies. Five TCS diagnostic patterns were defined on the basis of substantia nigra's and lenticular nuclei's echogenicity. TCS evaluations were performed by two blinded neuro-sonographers. Clinical diagnosis on all individuals was performed at baseline and at 4-year follow-up. The concordance rate between TCS patterns and clinical diagnosis and the specificity of TCS pattern to discriminate each group of individuals were compared at baseline and at follow-up. The concordance rate between TCS patterns and clinical diagnosis of all individuals was 84% at baseline and increased at follow-up (91%) significantly (p = 0.01). The specificity of TCS pattern in the comparison between patients diagnosed as affected by idiopathic Parkinson's disease and atypical parkinsonism showed a significant increase at follow-up (p = 0.03). Our study strongly confirms the role of TCS as a noninvasive and cost-effective tool in early diagnosis of movement disorders.