Sonographic discrimination of corticobasal degeneration vs progressive supranuclear palsy

Objective: To study the use of brain parenchyma sonography (BPS) in discriminating between patients with corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP). Methods: Thirteen patients with PSP and eight with CBD were studied with BPS according to a standardized protocol. Results: Seven (88%) of the eight CBD patients showed marked hyperechogenicity of the substantia nigra (SN) but none of eleven PSP patients (Mann-Whitney U test, p < 0.001). This finding indicated CBD with a positive predictive value of 100%. Marked dilatation of the third ventricle (width > 10 mm) was found in 10 (83%) of 12 PSP patients, but in none of the CBD patients (p < 0.005). BPS measurements of ventricle widths closely matched MRI measurements (Pearson correlation, r = 0.90, p < 0.001). The presence of at least one of the BPS findings 1) marked SN hyperechogenicity and 2) third-ventricle width < 10 mm indicated CBD with a sensitivity of 100%, a specificity of 83%, and a positive predictive value of 80%. Other BPS findings such as echogenicity of lentiform and caudate nuclei and widths of the frontal horns did not discriminate between CBD and PSP. One PSP patient could not be assessed because of insufficient acoustic temporal bone windows. Conclusions: Substantia nigra hyperechogenicity, reported earlier as characteristic brain parenchyma sonography finding in idiopathic Parkinson disease, is also typical for corticobasal degeneration.