Diffusion tensor imaging and correlations to Parkinson rating scales

Abstract

The contribution of various brain areas to the overall progression of Parkinson's disease remains to be determined. In this study, we apply MRI diffusion tensor imaging to investigate how alterations in diffusion relate to phenotype and symptoms measured by clinical rating scales. Sixty-four patients were investigated at baseline and three follow-ups (1, 3 and 5 years). Thirty-six patients remained in the last follow-up. Regions of interests included frontal white matter, basal ganglia, thalamus, and cerebellum. Scoring on the Unified Parkinson's Disease Rating Scale (UPDRS) I, II, III, Hoehn and Yahr (HY) scale and the Schwab and England scale (SE) was determined. Mean, radial, and axial diffusion and fractional anisotropy were modeled with phenotype and clinical scales in a multivariate/univariate analysis correcting for other covariates. Significance was set at 0.05 Bonferroni corrected. All rating scales except UPDRS III significantly correlated to the diffusion measures, as did clinical phenotype. Specifically, putamen, globus pallidus, and thalamus demonstrated higher diffusion with worsening scores. Diffusion in thalamus was higher in the tremor dominant phenotype than in postural imbalance and gait disturbance. Decline in overall functionality (UPDRS II and SE scale), including mental status (UPDRS I) and stage of the disease (HY scale), in Parkinson's disease is related to altered diffusion in the lentiform nucleus and thalamus. Motor function is not mirrored in diffusion changes, possibly due to medication. Tremor dominant PD patients show diffusion alterations in the thalamus, but the significance of this for tremor generation remains to be determined.

Microstructural changes in white matter associated with freezing of gait in Parkinson's disease

“…Interestingly, this tract projects from the thalamus to frontal motor areas, including the supplementary motor area, and showed increased MD in freezers in the current study. Similarly, Lenfeldt et al showed that thalamic diffusion differentiated tremor‐dominant from postural‐instability and gait disorder phenotypes. However, the burden of white matter hyperintensities proved not to be different between these phenotypes in a large cohort study …”

“…White matter changes in PD have been consistently linked to Hoehn and Yahr disease staging, self‐efficacy, mental status, and depression . As a much‐investigated biomarker of cognitive decline, white matter abnormalities were also related to the development of executive dysfunction, mild cognitive impairment, and dementia …”

The intrinsic resting state voice network in Parkinson's disease

“…Lenfeldt et al [] also found that increased UPDRS‐II scale scores were related to increased mean diffusivity in the putamen and the thalamus. The loss of axonal integrity, as well as decreased dopamine uptake in these regions, may help explain the decreased connectivity between the right putamen and the left thalamus.…”

Frontal white matter injuries predestine gait difficulties in Parkinson's disease

“…Diffusion tensor imaging (DTI) is a modern MRI technique sensitive to small‐scale brain damage. It measures the diffusion of water molecules, thereby quantifying neuronal integrity, and it has revealed diffusion alterations in several brain areas in PD . Still, its application in segregating phenotypes is limited.…”