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Abstract: Background and purpose: Using transcranial B-mode sonography (TCS), the first morphological marker for restless legs syndrome (RLS), hypoechogenicity of the substantia nigra (SN) has been found. The aim of this study was to validate SN hypoechogenicity as a morphological marker for RLS in a large patient cohort and to investigate further RLS-associated brain abnormalities using TCS. Methods: One hundred forty-three RLS patients (37 with symptomatic RLS) and 45 controls, matched for age and gender, underwent TCS by an experienced and independent rater who was blinded to clinical data. Results: The basal ganglia, ventricular system and cerebral lobes showed no RLS-specific abnormalities. SN hypoechogenicity correlated with a family history of RLS (p <0.001) and showed good sensitivity (82%), specificity (83%) and positive predictive value (94%). Red nucleus hyperechogenicity and brainstem raphe (BR) hypoechogenicity were more prevalent in RLS than in controls (both p <0.001) and correlated with reported periodic limb movements and depression, respectively (both p <0.001). Seventy-six percent of the patients (7% of controls) showed a co-occurrence of two or more sonographical abnormalities; 60% of symptomatic RLS patients showed the same sonographic features as the majority of RLS patients. Conclusions: TCS is a useful additional tool for diagnosing RLS and RLS-related disorders that demonstrate various brainstem abnormalities. [Copyright &y& Elsevier]

Summary: Background: Increased echogenicity of the substantia nigra (SN), as determined by transcranial sonography (TCS), is characteristic of idiopathic Parkinson''s disease (iPD). The results of initial retrospective studies indicate that this ultrasound sign is specific for iPD and can help to differentiate it from atypical parkinsonian syndromes (aPS); however, these early studies were done in patients with later disease stages and known clinical diagnosis. We aimed to determine the diagnostic value of TCS in the early stages of parkinsonian syndromes, when the clinical symptoms often do not enable a definite diagnosis to be made. Methods: 60 patients who presented with the first, but still unclear, clinical symptoms of parkinsonism had TCS in this prospective blinded study. Investigators were blinded to the results of the clinical investigations, the ultrasound findings, and the diagnosis at time of investigation. The patients were followed-up every 3 months for 1 year to assess and re-evaluate the clinical symptoms. The patients in whom a clinical diagnosis could not be made with certainty were investigated with raclopride PET or dopamine transporter single-photon emission computed tomography (SPECT), or both. Findings: A clinical diagnosis of parkinsonism could not be established at baseline in 38 patients. At 12 months, 39 patients were clinically categorised as having iPD. Compared with endpoint diagnosis, the sensitivity of TCS at baseline was 90%7% and the specificity was 82·4%; the positive predictive value of TCS for iPD was 92·9% and the classification accuracy was 88·3%. Interpretation: TCS is an easy to implement, non-invasive, and inexpensive technique that could help in the early differential diagnosis of parkinsonian syndromes. The routine use of TCS in the clinic could enable disease-specific therapy to be started earlier. Funding: Michael J Fox Foundation for Parkinson''s Research. [Copyright &y& Elsevier]