Neuroimaging Detectable Differences between Parkinson's Disease Motor Subtypes: A Systematic Review

Abstract

Background The neuroanatomical substrates of Parkinson's disease (PD) with tremor‐dominance (TD) and those with non‐tremor dominance (nTD), postural instability and gait difficulty (PIGD), and akinetic‐rigid (AR) are not fully differentiated. A better understanding of symptom specific pathoanatomical markers of PD subtypes may result in earlier diagnosis and more tailored treatment. Here, we aim to give an overview of the neuroimaging literature that compared PD motor subtypes. Methods A systematic literature review on neuroimaging studies of PD subtypes was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines. Search terms submitted to the PubMed database included: “Parkinson's disease”, “MRI” and “motor subtypes” (TD, nTD, PIGD, AR). The results are first discussed from macro to micro level of organization (i.e., (1) structural; (2) functional; and (3) molecular) and then by applied imaging methodology. Findings Several neuroimaging methods including diffusion imaging and positron emission tomography (PET) distinguish specific PD motor subtypes well, although findings are mixed. Furthermore, our review demonstrates that nTD‐PD patients have more severe neuroalterations compared to TD‐PD patients. More specifically, nTD‐PD patients have deficits within striato‐thalamo‐cortical (STC) circuitry and other thalamocortical projections related to cognitive and sensorimotor function, while TD‐PD patients tend to have greater cerebello‐thalamo‐cortical (CTC) circuitry dysfunction. Conclusions Based on the literature, STC and CTC circuitry deficits seem to be the key features of PD and the subtypes. Future research should make greater use of multimodal neuroimaging and techniques that have higher sensitivity in delineating subcortical structures involved in motor diseases.

Diffusion Measure Changes of Substantia Nigra Subregions and the Ventral Tegmental Area in Newly Diagnosed Parkinson’s Disease

“…A significant number of studies on group differences of brain structure diffusion measures have been done to observe DTI changes in PD [ 14 , 15 ]. Effects of dopamine loss due to death of dopaminergic neurons in SN causing imbalance of several other neurotransmitters in downstream motor systems and other structures have been illustrated through diffusion measure changes [ 23 , 24 ]. A review paper that compiled multiple different non-hypothesis-driven, diffusion assessments of PD and controls showed multiple instances where studies found correlations between motor symptoms and diffusion measure changes [ 14 ].…”

Elderly people with gait disorder in Lewy body diseases, white matter diseases, and their combination: A neuroimaging‐assisted analysis

“…1. Motor disorders in LBD 16,17 were divided into bladder and nonbladder: overactive bladder was equally noted in LBD (77%), dual (62%), and WMD (58%). In contrast, constipation was common in LBD (77%) and dual (60%) but rare in WMD (13%); and postural hypotension (> −20 mmHg) was noted in LBD (49%) dual (27%) but not in WMD (0%).…”

Imaging modalities in differential diagnosis of Parkinson’s disease: opportunities and challenges

“…Most PET 18 F-deoxy-glucose (FDG) studies have shown ordinary striatal metabolism in PD, thereby suitable in differentiating PD from other parkinsonian syndromes including progressive supranuclear palsy (PSP) or multiple system atrophy (MSA) [80,81]. By the technique, metabolic irregularities have been observed in a specific network in PD by investigating regional metabolic covariance patterns [82].…”