Evaluation of the Braak staging of brain pathology with H-MRS in patients with Parkinson's disease.

The Braak staging of Parkinson's disease (PD) pathology is usually based on the brain autopsy, which has not been confirmed in living patients of PD. In this study, we investigated the metabolites of medulla oblongata, substantia nigra (SN), putamen, and motor cortex by measuring N-acetylaspartate (NAA), choline-containing compounds (Cho) and creatine (Cr) in 22 patients of PD and 15 age-matched healthy controls, using single-voxel H-magnetic resonance spectroscopy (H-MRS). The results showed that NAA/Cr in SN was lower in PD group than that in control group (p=0.006), however, there was no difference for NAA/Cr and Cho/Cr between PD group and control group in other regions. In SN, NAA/Cr was negatively correlated with Unified Parkinson's Disease Rating Scale (UPDRS) (r=-0.743, p=0.002) and Hoehn-Yahr staging (r=-0.714, p=0.003), while Cho/Cr was positively correlated with UPDRS (r=0.850, p<0.001) and Hoehn-Yahr staging (r=0.647, p=0.009). In PD group, the variance of NAA/Cr in SN was significantly larger than that in other regions (p=0.005), but there was no difference for the variance of Cho/Cr among regions of interesting (ROIs) (p=0.267). These results indicate that SN is the most seriously injured region in PD, and the metabolites in SN measured by H-MRS is correlated with the severity of PD. However, the Braak staging of PD pathology is not validated by H-MRS.