Neuroimaging correlates of postural instability in Parkinson's disease

BackgroundPostural instability (PI) is a common disabling symptom in Parkinson's disease (PD), but little is known on its pathophysiological basis.ObjectiveIn this study, we aimed to identify the brain structures associated with PI in PD patients, using different MRI approaches.MethodsWe consecutively enrolled 142 PD patients and 45 control subjects. PI was assessed using the MDS-UPDRS-III pull-test item (PT). A whole-brain regression analysis identified brain areas where grey matter (GM) volume correlated with the PT score in PD patients. Voxel-based morphometry (VBM) and Tract-Based Spatial Statistics (TBSS) were also used to compare unsteady (PT >= 1) and steady (PT = 0) PD patients. Associations between GM volume in regions of interest (ROI) and several clinical features were then investigated using LASSO regression analysis.ResultsPI was present in 44.4% of PD patients. The whole-brain approach identified the bilateral inferior frontal gyrus (IFG) and superior temporal gyrus (STG) as the only regions associated with the presence of postural instability. VBM analysis showed reduced GM volume in fronto-temporal areas (superior, middle, medial and inferior frontal gyrus, and STG) in unsteady compared with steady PD patients, and the GM volume of these regions was selectively associated with the PT score and not with any other motor or non-motor symptom.ConclusionsThis study demonstrates a significant atrophy of fronto-temporal regions in unsteady PD patients, suggesting that these brain areas may play a role in the pathophysiological mechanisms underlying postural instability in PD. This result paves the way for further studies on postural instability in Parkinsonism.

Automated summary

This study identified the bilateral inferior frontal gyrus (IFG) and superior temporal gyrus (STG) as regions associated with postural instability in Parkinson's disease (PD) patients. Voxel-based morphometry (VBM) analysis showed reduced grey matter volume in fronto-temporal areas in unsteady PD patients, and this reduction was selectively associated with the postural instability score.