Transcranial ultrasound shows nigral hypoechogenicity in restless legs syndrome. - Schmidauer,C.; Sojer,M.; Seppi,K.; Stockner,H.; Hogl,B.; Biedermann,B.; Brandauer,E.; Peralta,C.M.; Wenning,G.K.; Poewe,W. (Ann Neurol, 2005)