Structural changes of substantia nigra in patients with unilateral Parkinson′s disease

Magnetic resonance imaging (MRI) findings were studied in 19 patients with non-dementia Parkinson′s disease (PD) Hoehn-Yahr Stage 1 and 1.5 and 38 healthy subjects. The width and area of pars compacta of substantia nigra (SNc), substantia nigra (SN) and midbrain were measured. The width and area ratios of SNc to SN were calculated. Compared with controls, the widths of right SNc was narrower, bilateral ratios of SNc to SN width were decreased in PD group. As to the area of substantia nigra, there was no significant difference between PD and controls. The width of left SN and the ratio of right SNc to SN width was negatively correlation with age of patients. The ratio of left SNc to SN width, the area of bilateral SNc and left SN, as well as the ratio of right SNc to SN area had negative correlation with the disease duration; however, there was no correlation with gender, Hoehn-Yahr Stage, the Unified Parkinson disease rating scale score, mini mental state scale, education years, levodopa equivalent daily dose, Hamilton Depression Scale or Hamilton Anxiety Scale in PD group. The results indicate that there are bilateral structural changes of SN in unilateral PD patients, which may be more significant with increasing disease duration. The measurement of SNc width and SN area can be used as an objective indicator for diagnosis and disease progression monitoring of PD. Key words: Parkinson disease; Magnetic resonance imaging; Pars compacta of substantia nigra