Prevalence of smell impairments and substantia nigra hyperrechogeneicity in Lithuanians, born in 1964

Abstract

Objectives: to determine the prevalence of smell impairments and changes in substantia nigra (SN) echogeneicity on transcranial sonography (TCS) in healthy adult population and to evaluate the link between the two. Methods: 295 subjects - 59% women and 41% men, born in 1964 (aged 48,42±0,04 at the moment of the study), participating in a population study "Connection between genetic and lifestyle risk factors for chronic disease risks since childhood" were screened for smell impairments, using Sniffin' Sticks 12 test, as well as for SN echogeneicity changes using TCS. They all underwent neurological examination with focus on extrapyramidal signs and none was found to have PD at the moment of the study. Results: sufficient acoustic temporal bone window allowed complete TCS results to be obtained in 90.5% of cases. In 6.1% of examined cases unilateral or bilateral enlargement of SN area (hiperechogeneicity) was detected (using the cutoff value of 0.26 cm²). 24,1% of participants had at least mild hiposmia. Changes in SN echogeneicity correlated positively with smell impairments (p<0.05). 9.8% of participants were found to have both - smell and SN echogeneicity impairments. Conclusions: almost ¹∕₄ of the studied population was found to have at least mild smell impairments. In similar proportion of cases hyperechogeneicity of SN was detected. A positive correlation between symptoms was observed.