Does normal substantia nigra echogenicity make a difference in Parkinson’s disease diagnosis? A real clinical practice follow-up study

Objectives Substantia nigra hyperechogenicity (SN+) detected by transcranial ultrasound (TUS) is useful for Parkinson’s disease (PD) diagnosis. Approximately 15% false negative results of unknown significance are reported. However, most TUS studies are transversal, and diagnosis of PD may change during follow-up. Methods Analysis of our prospective registry of TUS in clinical practice, selecting patients with sufficient bone window, to whom TUS was performed because of suspected PD, and a minimum of 3-year follow-up. Subjects were classified regarding SN echogenicity (SN+/SN−). Results 172 patients (122 SN+, 50 SN−), mean age 71 years (25–90), were included. At the end of follow-up, PD diagnosis was retained by 91% SN+ vs. 54% SN− subjects ( p