Neuroimaging and neurophysiological evaluation of severity of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease presenting characteristic motor features. Severity is usually assessed by clinical symptoms; however, few objective indicators are available. In this study, we evaluated the utility of dopamine transporter (DAT) imaging and subthalamic nucleus (STN) activities as indicators of PD severity.

Twelve hemispheres of ten patients with PD who underwent deep brain stimulation (DBS) were included in this study. Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part 3 scores were used to evaluate clinical severity. The relationship between specific binding ratio (SBR) of DAT imaging and the root mean square (RMS) of STN micro-electrode recording (MER) was evaluated.

A negative correlation was detected between the MDS-UPDRS part 3 scores and SBR (N = 20, R² = 0.418; P = 0.002). With respect to subscores, rigidity (R² = 0.582; P < 0.001) and bradykinesia (R² = 0.378; P = 0.004) showed negative correlation with SBR, whereas tremor showed no correlation (R² = 0.054; P = 0.324) (N = 20). On the other hand, no correlation was found between MER and the MDS-UPDRS part 3 scores in ten hemispheres of six patients.

DAT findings may be useful in evaluating PD severity, especially rigidity and bradykinesia.