Substantia nigra echomorphology in the healthy very old: Correlation with motor slowing

Transcranial sonography reveals an increase in echogenicity in the substantia nigra of patients with idiopathic Parkinson's disease. Marked hyperechogenicity has also been described in 9% of the healthy population and is associated with subtle clinical or functional neuroimaging findings suggestive of changes in nigrostriatal function. It has therefore been hypothesised that a hyperechogenic substantia nigra represents an early stage of nigral degeneration or a predisposition for Parkinson's disease. In the present study, we correlated sonographic findings with motor and cognitive deficits in a group of healthy, very elderly subjects. Marked and moderately increased substantia nigra echogenicity was present in 25% and 21% of our healthy, very elderly subjects, respectively, and correlated strongly with the presence of extrapyramidal symptoms in the absence of cognitive deficits. The high incidence of substantia nigra hyperechogenicity measured in our very elderly subjects compared with previous TCS studies suggests that the prevalence of this feature increases with age and is consistent with the higher prevalence of Parkinson's disease in advanced age, as well as the increased frequency of extrapyramidal symptoms. Our results indicate that this simple technique can be used to identify and quantify brain changes associated with subtle motor dysfunction in the very elderly.