Enlarged hyperechogenic substantia nigra is related to motor performance and olfaction in the elderly.

ABSTRACT

Enlarged substantia nigra hyperechogenicity (SN+) assessed by transcranial sonography (TCS) may be associated with Parkinson's disease (PD) risk markers such as impaired motor performance and hyposmia. The aim of this multicenter cross-sectional study was to define the association between SN+ and these risk markers in a large population older than 50 years without the diagnosis of PD. In three centers (Tuebingen, Homburg, and Innsbruck), 1,839 individuals were examined. The echostatus of the SN was assessed by TCS, motor performance by the Unified Parkinson's Disease Rating Scale (UPDRS) motor score, and olfactory function with Sniffin' Sticks. From the 1,603 subjects included in the analysis, 16.2% were SN+, 23.0% scored above zero in the UPDRS motor section, and 28.0% were hyposmic as defined by less than 75% correctly classified Sniffin' Sticks. SN+ was associated with a UPDRS motor score above zero (OR 1.45, 95% CI 1.08-1.96) and with a lower odor identification capability (OR 1.48, 95% CI 1.12-1.96). The combination of these two features (OR 1.98, 95% CI 1.25-3.15) and UPDRS motor scores >or=3 lead to higher OR. It is concluded that SN+, impaired motor performance, and hyposmia are frequently observed in the elderly and in isolation are unspecific and of limited use to predict a subject's risk for PD. Whether the association of SN+ with both impaired motor performance and hyposmia as seen in this study predicts an increased risk for the development of PD needs to be evaluated in the follow-up investigations.