No correlation of substantia nigra echogenicity and nigrostriatal degradation in Parkinson's disease

Background: Substantia nigra hyperechogenicity assessed by transcranial sonography is a typical finding in up to 90% of patients with idiopathic Parkinson's disease, although its value as a surrogate marker for disease progression in Parkinson's disease is controversial. 123I-FP-CITsingle photon emission computed tomography (SPECT) represents an established paraclinical surrogate marker to quantify the nigrostriatal dopaminergic deficit in Parkinson's disease. Whereas most studies found no correlation between extent of substantia nigra echogenicity and the putaminal FP-CIT binding ratio, a more recent analysis reported opposite results. Methods: In 92 patients with Parkinson's disease the substantia nigra echogenicity was compared with the putaminal FP- CIT binding ratio using an investigator- independent SPECT analysis protocol and with several clinical parameters. Results: No correlation was found between the substantia nigra hyperechogenicity and the FP- CIT binding ratio or the disease severity. Conclusions: Substantia nigra hyperechogenicity does not reflect the degree of the nigrostriatal degeneration or the clinical state of the disease progression. VC 2012 Movement Disorder Society