The in vivo distribution of brain tissue loss in Richardson's syndrome and PSP-parkinsonism: a VBM-DARTEL study

Histologic tau lesions and magnetic resonance imaging biomarkers differ across two progressive supranuclear palsy variants

Progressive supranuclear palsy is a neurodegenerative disease characterized by the deposition of four-repeat tau in neuronal and glial lesions in the brainstem, cerebellar, subcortical and cortical brain regions. There are varying clinical presentations of progressive supranuclear palsy with different neuroimaging signatures, presumed to be due to different topographical distributions and burden of tau. The classic Richardson syndrome presentation is considered a subcortical variant, whilst progressive supranuclear palsy with predominant speech and language impairment is considered a cortical variant, although the pathological underpinnings of these variants are unclear. In this case-control study, we aimed to determine whether patterns of regional tau pathology differed between these variants and whether tau burden correlated with neuroimaging. Thirty-three neuropathologically confirmed progressive supranuclear palsy patients with either the Richardson syndrome (n = 17) or speech/language (n = 16) variant and ante-mortem magnetic resonance imaging were included. Tau lesion burden was semi-quantitatively graded in cerebellar, brainstem, subcortical and cortical regions and combined to form neuronal and glial tau scores. Regional magnetic resonance imaging volumes were converted to Z-scores using 33 age- and sex-matched controls. Diffusion tensor imaging metrics, including fractional anisotropy and mean diffusivity, were calculated. Tau burden and neuroimaging metrics were compared between groups and correlated using linear regression models. Neuronal and glial tau burden were higher in motor and superior frontal cortices in the speech/language variant. In the subcortical and brainstem regions, only the glial tau burden differed, with a higher burden in globus pallidus, subthalamic nucleus, substantia nigra and red nucleus in Richardson's syndrome. No differences were observed in the cerebellar dentate and striatum. Greater volume loss was observed in the motor cortex in the speech/language variant and in the subthalamic nucleus, red nucleus and midbrain in Richardson's syndrome. Fractional anisotropy was lower in the midbrain and superior cerebellar peduncle in Richardson's syndrome. Mean diffusivity was greater in the superior frontal cortex in the speech/language variant and midbrain in Richardson's syndrome. Neuronal tau burden showed associations with volume loss, lower fractional anisotropy and higher mean diffusivity in the superior frontal cortex, although these findings did not survive correction for multiple comparisons. Results suggest that a shift in the distribution of tau, particularly neuronal tau, within the progressive supranuclear palsy network of regions is driving different clinical presentations in progressive supranuclear palsy. The possibility of different disease epicentres in these clinical variants has potential implications for the use of imaging biomarkers in progressive supranuclear palsy.

Structural correlates of survival in progressive supranuclear palsy

INTRODUCTION

Many studies of the Richardson's syndrome phenotype of progressive supranuclear palsy (PSP) have elucidated regions of progressive atrophy and neural correlates of clinical severity. However, the neural correlates of survival and how these differ according to variant phenotypes are poorly understood. We set out to identify structural changes that predict severity and survival from scanning date to death.

METHODS

Structural magnetic resonance imaging data from 112 deceased people with clinically defined 'probable' or 'possible' PSP were analysed. Neuroanatomical regions of interest volumes, thickness and area were correlated with 'temporal stage', defined as the ratio of time from symptom onset to death, time from scan to death ('survival from scan'), and in a subset of patients, clinical severity, adjusting for age and total intracranial volume. Forty-nine participants had post mortem confirmation of the diagnosis.

RESULTS

Using T1-weighted magnetic resonance imaging, we confirmed the midbrain, and bilateral cortical structural correlates of contemporary disease severity. Atrophy of the striatum, cerebellum and frontotemporal cortex correlate with temporal stage and survival from scan, even after adjusting for severity. Subcortical structure-survival relationships were stronger in Richardson's syndrome than variant phenotypes.

CONCLUSIONS

Although the duration of PSP varies widely between people, an individual's progress from disease onset to death (their temporal stage) reflects atrophy in striatal, cerebellar and frontotemporal cortical regions. Our findings suggest magnetic resonance imaging may contribute to prognostication and stratification of patients with heterogenous clinical trajectories and clarify the processes that confer mortality risk in PSP.

Differentiating between common PSP phenotypes using structural MRI: a machine learning study

BACKGROUND

Differentiating Progressive supranuclear palsy-Richardson's syndrome (PSP-RS) from PSP-Parkinsonism (PSP-P) may be extremely challenging. In this study, we aimed to distinguish these two PSP phenotypes using MRI structural data.

METHODS

Sixty-two PSP-RS, 40 PSP-P patients and 33 control subjects were enrolled. All patients underwent brain 3 T-MRI; cortical thickness and cortical/subcortical volumes were extracted using Freesurfer on T1-weighted images. We calculated the automated MR Parkinsonism Index (MRPI) and its second version including also the third ventricle width (MRPI 2.0) and tested their classification performance. We also employed a Machine learning (ML) classification approach using two decision tree-based algorithms (eXtreme Gradient Boosting [XGBoost] and Random Forest) with different combinations of structural MRI data in differentiating between PSP phenotypes.

RESULTS

MRPI and MRPI 2.0 had AUC of 0.88 and 0.81, respectively, in differentiating PSP-RS from PSP-P. ML models demonstrated that the combination of MRPI and volumetric/thickness data was more powerful than each feature alone. The two ML algorithms showed comparable results, and the best ML model in differentiating between PSP phenotypes used XGBoost with a combination of MRPI, cortical thickness and subcortical volumes (AUC 0.93 ± 0.04). Similar performance (AUC 0.93 ± 0.06) was also obtained in a sub-cohort of 59 early PSP patients.

CONCLUSION

The combined use of MRPI and volumetric/thickness data was more accurate than each MRI feature alone in differentiating between PSP-RS and PSP-P. Our study supports the use of structural MRI to improve the early differential diagnosis between common PSP phenotypes, which may be relevant for prognostic implications and patient inclusion in clinical trials.

Large-scale activation likelihood estimation meta-analysis of parkinsonian disorders

Parkinsonism is a feature of several neurodegenerative disorders, including Parkinson's disease, progressive supranuclear palsy, corticobasal syndrome and multiple system atrophy. Neuroimaging studies have yielded insights into parkinsonian disorders; however, due to variability in results, the brain regions consistently implicated in these disorders remain to be characterized. The aim of this meta-analysis was to identify consistent brain abnormalities in individual parkinsonian disorders (Parkinson's disease, progressive supranuclear palsy, corticobasal syndrome and multiple system atrophy) and to investigate any shared abnormalities across disorders. A total of 44 591 studies were systematically screened following searches of two databases. A series of whole-brain activation likelihood estimation meta-analyses were performed on 132 neuroimaging studies (69 Parkinson's disease; 23 progressive supranuclear palsy; 17 corticobasal syndrome; and 23 multiple system atrophy) utilizing anatomical MRI, perfusion or metabolism PET and single-photon emission computed tomography. Meta-analyses were performed in each parkinsonian disorder within each imaging modality, as well as across all included disorders. Results in progressive supranuclear palsy and multiple system atrophy aligned with current imaging markers for diagnosis, encompassing the midbrain, and brainstem and putamen, respectively. PET imaging studies of patients with Parkinson's disease most consistently reported abnormality of the middle temporal gyrus. No significant clusters were identified in corticobasal syndrome. When examining abnormalities shared across all four disorders, the caudate was consistently reported in MRI studies, whilst the thalamus, inferior frontal gyrus and middle temporal gyri were commonly implicated by PET. To our knowledge, this is the largest meta-analysis of neuroimaging studies in parkinsonian disorders and the first to characterize brain regions implicated across parkinsonian disorders.

Reduced phonemic fluency in progressive supranuclear palsy is due to dysfunction of dominant BA6

Background

Reduced phonemic fluency is extremely frequent in progressive supranuclear palsy (PSP), but its neural correlate is yet to be defined.

Objective

We explored the hypothesis that poor fluency in PSP might be due to neurodegeneration within a dominant frontal circuit known to be involved in speech fluency, including the opercular area, the superior frontal cortex (BA6), and the frontal aslant tract connecting these two regions.

Methods

We correlated performance on a letter fluency task (F, A, and S, 60 s for each letter) with brain metabolism as measured with Fluoro-deoxy-glucose Positron Emission Tomography, using Statistical Parametric Mapping, in 31 patients with PSP.

Results

Reduced letter fluency was associated with significant hypometabolism at the level of left BA6.

Conclusion

Our finding is the first evidence that in PSP, as in other neurogical disorders, poor self-initiated, effortful verbal retrieval appears to be linked to dysfunction of the dominant opercular-aslant-BA6 circuit.

Evolving concepts in progressive supranuclear palsy and other 4-repeat tauopathies

Tauopathies are classified according to whether tau deposits predominantly contain tau isoforms with three or four repeats of the microtubule-binding domain. Those in which four-repeat (4R) tau predominates are known as 4R-tauopathies, and include progressive supranuclear palsy, corticobasal degeneration, argyrophilic grain disease, globular glial tauopathies and conditions associated with specific MAPT mutations. In these diseases, 4R-tau deposits are found in various cell types and anatomical regions of the brain and the conditions share pathological, pathophysiological and clinical characteristics. Despite being considered 'prototype' tauopathies and, therefore, ideal for studying neuroprotective agents, 4R-tauopathies are still severe and untreatable diseases for which no validated biomarkers exist. However, advances in research have addressed the issues of phenotypic overlap, early clinical diagnosis, pathophysiology and identification of biomarkers, setting a road map towards development of treatments. New clinical criteria have been developed and large cohorts with early disease are being followed up in prospective studies. New clinical trial readouts are emerging and biomarker research is focused on molecular pathways that have been identified. Lessons learned from failed trials of neuroprotective drugs are being used to design new trials. In this Review, we present an overview of the latest research in 4R-tauopathies, with a focus on progressive supranuclear palsy, and discuss how current evidence dictates ongoing and future research goals.

Update on neuroimaging for categorization of Parkinson's disease and atypical parkinsonism

PURPOSE OF REVIEW

Differential diagnosis of Parkinsonism may be difficult. The objective of this review is to present the work of the last three years in the field of imaging for diagnostic categorization of parkinsonian syndromes focusing on progressive supranuclear palsy (PSP) and multiple system atrophy (MSA).

RECENT FINDINGS

Two main complementary approaches are being pursued. The first seeks to develop and validate manual qualitative or semi-quantitative imaging markers that can be easily used in clinical practice. The second is based on quantitative measurements of magnetic resonance imaging abnormalities integrated in a multimodal approach and in automatic categorization machine learning tools.

SUMMARY

These two complementary approaches obtained high diagnostic around 90% and above in the classical Richardson form of PSP and probable MSA. Future work will determine if these techniques can improve diagnosis in other PSP variants and early forms of the diseases when all clinical criteria are not fully met.

Diffusion tensor imaging analysis in three progressive supranuclear palsy variants

BACKGROUND

Clinical variants of progressive supranuclear palsy (PSP) include the classic Richardson's syndrome (PSP-RS), as well as cortical presentations such as PSP-speech/language (PSP-SL) and subcortical presentations such as PSP-parkinsonism (PSP-P). Patterns of white matter tract degeneration underlying these variants, and the degree to which white matter patterns could differentiate these variants, is unclear.

METHODS

Forty-nine PSP patients (28 PSP-RS, 12 PSP-P, and 9 PSP-SL) were recruited by the Neurodegenerative Research Group and underwent diffusion tensor imaging. Regional diffusion tensor imaging metrics were compared across PSP variants using Bayesian linear mixed-effects models, with inter-variant differentiation assessed using the area under the receiver operator characteristic curve (AUROC).

RESULTS

All three variants showed degeneration of the body of the corpus callosum, posterior thalamic radiation, superior cerebellar peduncle, internal and external capsule, and superior fronto-occipital fasciculus. PSP-RS showed greater degeneration of superior cerebellar peduncle compared to PSP-P and PSP-SL, whereas PSP-SL showed greater degeneration of body and genu of the corpus callosum, internal capsule, external capsule, and superior longitudinal fasciculus compared to the other variants. Fractional anisotropy in body of the corpus callosum provided excellent differentiation of PSP-SL from both PSP-P and PSP-RS (AUROC = 0.91 and 0.92, respectively). Moderate differentiation of PSP-RS and PSP-P was achieved with fractional anisotropy in superior fronto-occipital fasciculus (AUROC = 0.68) and mean diffusivity in the superior cerebellar peduncle (AUROC = 0.65).

CONCLUSION

In this pilot study, patterns of white matter tract degeneration differed across PSP-RS, PSP-SL, and PSP-P, with the body of the corpus callosum showing some utility in the differentiation of PSP-SL from the other two variants.

Language impairment in progressive supranuclear palsy and corticobasal syndrome

Although commonly known as movement disorders, progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS) may present with changes in speech and language alongside or even before motor symptoms. The differential diagnosis of these two disorders can be challenging, especially in the early stages. Here we review their impact on speech and language. We discuss the neurobiological and clinical-phenomenological overlap of PSP and CBS with each other, and with other disorders including non-fluent agrammatic primary progressive aphasia and primary progressive apraxia of speech. Because language impairment is often an early and persistent problem in CBS and PSP, there is a need for improved methods for language screening in primary and secondary care, and more detailed language assessments in tertiary healthcare settings. Improved language assessment may aid differential diagnosis as well as inform clinical management decisions.

The Role of Magnetic Resonance Imaging for the Diagnosis of Atypical Parkinsonism

The diagnosis of Parkinson's disease and atypical Parkinsonism remains clinically difficult, especially at the early stage of the disease, since there is a significant overlap of symptoms. Multimodal MRI has significantly improved diagnostic accuracy and understanding of the pathophysiology of Parkinsonian disorders. Structural and quantitative MRI sequences provide biomarkers sensitive to different tissue properties that detect abnormalities specific to each disease and contribute to the diagnosis. Machine learning techniques using these MRI biomarkers can effectively differentiate atypical Parkinsonian syndromes. Such approaches could be implemented in a clinical environment and improve the management of Parkinsonian patients. This review presents different structural and quantitative MRI techniques, their contribution to the differential diagnosis of atypical Parkinsonian disorders and their interest for individual-level diagnosis.

Brain volume and flortaucipir analysis of progressive supranuclear palsy clinical variants

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All PSP variants showed atrophy or flortaucipir uptake in subcortical structures.

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Speech/language, frontal and corticobasal variants showed cortical involvement.

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Dentatorubrothalamic tract involvement was only seen in some variants.

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PSP variants show different patterns of damage to subcortical-cortical circuitry.

Background and purpose

Progressive supranuclear palsy (PSP) is a neurodegenerative tauopathy that is associated with different clinical variants, including PSP-Richardson's syndrome (PSP-RS), PSP-parkinsonism (PSP-P), PSP-corticobasal syndrome (PSP-CBS), PSP-frontal (PSP-F), PSP-progressive gait freezing (PSP-PGF) and PSP-speech/language (PSP-SL). While PSP-RS has been well-characterized on neuroimaging, the characteristics of the other atypical variants are less well defined and it is unknown how they compare to each other or relate to neuropathology. We aimed to assess and compare regional atrophy on MRI and [¹⁸F]flortaucipir uptake on PET across PSP variants.

Materials and methods

105 PSP patients (53 PSP-RS, 23 PSP-SL, 12 PSP-P, 8 PSP-CBS, 5 PSP-F and 4 PSP-PGF) underwent volumetric MRI, with 59 of these also undergoing flortaucipir PET. Voxel-level and region-level analyses were performed comparing PSP variants to 30 controls and to each other. Semi-quantitative tau burden measurements were also performed in 21 patients with autopsy-confirmed PSP.

Results

All variants showed evidence for atrophy or increased flortaucipir uptake in striatum, globus pallidus and thalamus. Superior cerebellar peduncle volume loss was only observed in PSP-RS, PSP-CBS and PSP-F. Volume loss in the frontal lobes was observed in PSP-SL, PSP-CBS and PSP-F, with these variants also showing highest cortical tau burden at autopsy. The PSP-P and PSP-PGF variants showed more restricted patterns of neurodegeneration predominantly involving striatum, globus pallidus, subthalamic nucleus and thalamus. The PSP-SL variant showed greater volume loss and flortaucipir uptake in supplementary motor area and motor cortex compared to all other variants, but showed less involvement of subthalamic nucleus and midbrain. Compared to PSP-RS, PSP-P had larger midbrain volume and greater flortaucipir uptake in putamen.

Conclusion

The PSP variants have different patterns of involvement of subcortical circuitry, perhaps suggesting different patterns of disease spread through the brain. These findings will be important in the development of appropriate neuroimaging biomarkers for the different PSP variants.

Diffusion Tensor MRI to Distinguish Progressive Supranuclear Palsy from α-Synucleinopathies

Background The differential diagnosis of progressive supranuclear palsy (PSP) and Lewy body disorders, which include Parkinson disease and dementia with Lewy bodies, is often challenging due to the overlapping symptoms. Purpose To develop a diagnostic tool based on diffusion tensor imaging (DTI) to distinguish between PSP and Lewy body disorders at the individual-subject level. Materials and Methods In this retrospective study, skeletonized DTI metrics were extracted from two independent data sets: the discovery cohort from the Swedish BioFINDER study and the validation cohort from the Penn Frontotemporal Degeneration Center (data collected between 2010 and 2018). Based on previous neuroimaging studies and neuropathologic evidence, a combination of regions hypothesized to be sensitive to pathologic features of PSP were identified (ie, the superior cerebellar peduncle and frontal white matter) and fractional anisotropy (FA) was used to compute an FA score for each individual. Classification performances were assessed by using logistic regression and receiver operating characteristic analysis. Results In the discovery cohort, 16 patients with PSP (mean age ± standard deviation, 73 years ± 5; eight women, eight men), 34 patients with Lewy body disorders (mean age, 71 years ± 6; 14 women, 20 men), and 44 healthy control participants (mean age, 66 years ± 8; 26 women, 18 men) were evaluated. The FA score distinguished between clinical PSP and Lewy body disorders with an area under the curve of 0.97 ± 0.04, a specificity of 91% (31 of 34), and a sensitivity of 94% (15 of 16). In the validation cohort, 34 patients with PSP (69 years ± 7; 22 women, 12 men), 25 patients with Lewy body disorders (70 years ± 7; nine women, 16 men), and 32 healthy control participants (64 years ± 7; 22 women, 10 men) were evaluated. The accuracy of the FA score was confirmed (area under the curve, 0.96 ± 0.04; specificity, 96% [24 of 25]; and sensitivity, 85% [29 of 34]). Conclusion These cross-validated findings lay the foundation for a clinical test to distinguish progressive supranuclear palsy from Lewy body disorders. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Shah in this issue.

Increased Signal in the Superior Cerebellar Peduncle of Patients with Progressive Supranuclear Palsy

Objective

The provisional diagnosis of progressive supranuclear palsy (PSP) depends on a combination of typical clinical features and specific MRI findings, such as atrophy of the tegmentum in the midbrain. Atrophy of the superior cerebellar peduncle (SCP) distinguishes PSP from other types of parkinsonism. Histological factors affect the conventional fluid-attenuated inversion recovery (FLAIR) signals, such as the extent of neuronal loss and gliosis.

Methods

We investigated patients with PSP to verify the percentage of patients with various PSP phenotypes presenting a high signal intensity in the SCP. Three interviewers, who were not informed about the clinical data, visually inspected the presence or absence of a high signal intensity in the SCP on the FLAIR images. We measured the pixel value in the SCP of each patient. Clinical characteristics were evaluated using the Mann-Whitney test, followed by the χ² test.

Results

Ten of the 51 patients with PSP showed a high signal intensity in the SCP on FLAIR MRI. Higher pixel values were observed within the SCP of patients with a high signal intensity in the SCP than in patients without a high signal intensity (p < 0.001). The sensitivity and specificity of the high signal intensity in the SCP of patients with PSP was 19.6% and 100%, respectively. This finding was more frequently observed in patients with PSP with Richardson’s syndrome (PSP-RS) (25.7%) than other phenotypes (6.2%).

Conclusion

The high signal intensity in the SCP on FLAIR MRI might be an effective diagnostic tool for PSP-RS.

Functional MRI in Atypical Parkinsonisms

The present chapter reports the current knowledge on the use of functional MRI (fMRI) in patients with atypical parkinsonisms, including Multiple System Atrophy, Corticobasal Syndrome and Progressive Supranuclear Palsy syndrome. Both resting state functional connectivity and task-based brain activity abnormalities are reported in atypical parkinsonisms relative to healthy controls and Parkinson's disease patients. Functional alterations were observed earlier than structural damage and may help to make early diagnosis. The chapter also examines the few longitudinal evidence on fMRI changes in patients with these conditions. The potential use of fMRI techniques in aiding the differential diagnosis, accurately measuring disease progression and assessing the effectiveness of therapeutic interventions is discussed.

Structural Imaging in Atypical Parkinsonism

Qualitative and quantitative structural magnetic resonance imaging offer objective measures of the underlying neurodegeneration in atypical parkinsonism. Regional changes in tissue volume, signal changes and increased deposition of iron as assessed with different structural MRI techniques are surrogate markers of underlying neurodegeneration and may reflect cell loss, microglial proliferation and astroglial activation. Structural MRI has been explored as a tool to enhance diagnostic accuracy in differentiating atypical parkinsonian disorders (APDs). Moreover, the longitudinal assessment of serial structural MRI-derived parameters offers the opportunity for robust inferences regarding the progression of APDs. This review summarizes recent research findings as (1) a diagnostic tool for APDs as well as (2) as a tool to assess longitudinal changes of serial MRI-derived parameters in the different APDs.

Prospective Characterization of Cognitive Function in Typical and 'Brainstem Predominant'Progressive Supranuclear Palsy Phenotypes

Objective

Clinicopathological studies over the last decade have broadened the clinical spectrum of progressive supranuclear palsy (PSP) to include several distinct clinical syndromes. We examined the cognitive profiles of patients with PSP-Richardson’s syndrome (PSP-RS) and two atypical ‘brainstem predominant’ PSP phenotypes (PSP-parkinsonism, PSP-P; and PSP-pure akinesia with gait freezing, PSP-PAGF) using a comprehensive neuropsychological battery.

Methods

Fourteen patients diagnosed as PSP-RS, three patients with PSP-P and four patients with PSP-PAGF were assessed using a comprehensive battery of neuropsychological tests.

Results

The typical PSP-RS subgroup demonstrated greater impairments in processing speed [t(19) = -4.10, p = 0.001 (d =1.66)] and executive function [t(19) = -2.63, p = 0.02 (d = 1.20)] compared to the ‘brainstem predominant’ PSP phenotype.

Conclusion

This is the first prospective study to demonstrate that PSP-RS and ‘brainstem predominant’ PSP phenotypes can be differentiated on cognitive grounds. These differences correspond with variations in pathological profiles reported in the literature.

Reproducible network and regional topographies of abnormal glucose metabolism associated with progressive supranuclear palsy: Multivariate and univariate analyses in American and Chinese patient cohorts

Progressive supranuclear palsy (PSP) is a rare movement disorder and often difficult to distinguish clinically from Parkinson's disease (PD) and multiple system atrophy (MSA) in early phases. In this study, we report reproducible disease-related topographies of brain network and regional glucose metabolism associated with PSP in clinically-confirmed independent cohorts of PSP, MSA, and PD patients and healthy controls in the USA and China. Using ¹⁸ F-FDG PET images from PSP and healthy subjects, we applied spatial covariance analysis with bootstrapping to identify a PSP-related pattern (PSPRP) and estimate its reliability, and evaluated the ability of network scores for differential diagnosis. We also detected regional metabolic differences using statistical parametric mapping analysis. We produced a highly reliable PSPRP characterized by relative metabolic decreases in the middle prefrontal cortex/cingulate, ventrolateral prefrontal cortex, striatum, thalamus and midbrain, covarying with relative metabolic increases in the hippocampus, insula and parieto-temporal regions. PSPRP network scores correlated positively with PSP duration and accurately discriminated between healthy, PSP, MSA and PD groups in two separate cohorts of parkinsonian patients at both early and advanced stages. Moreover, PSP patients shared many overlapping areas with abnormal metabolism in the same cortical and subcortical regions as in the PSPRP. With rigorous cross-validation, this study demonstrated highly comparable and reproducible PSP-related metabolic topographies at network and regional levels across different patient populations and PET scanners. Metabolic brain network activity may serve as a reliable and objective marker of PSP, although cross-validation applying recent diagnostic criteria and classification is warranted.

Diagnostic potential of dentatorubrothalamic tract analysis in progressive supranuclear palsy

BACKGROUND

The differentiation of progressive supranuclear palsy-parkinsonism (PSP-P) from Parkinson's disease (PD) remains a major clinical challenge.

OBJECTIVES

To evaluate the diagnostic potential of observer-independent assessments of microstructural integrity within infratentorial brain regions to differentiate PSP-Richardson's syndrome (PSP-RS), PSP-P and PD.

METHODS

3T MRI parameters of mean diffusivity, fractional anisotropy, grey and white matter volumes from patients with PSP-RS (n = 12), PSP-P (n = 12) and mean disease duration of 2.4 ± 1.7 years were compared with PD patients (n = 20) and healthy controls (n = 23) by using statistical parametric mapping and the spatially unbiased infratentorial template. Subsequently MRI measurements of the dentatorubrothalamic tract were determined observer-independently by a validated probabilistic infratentorial atlas. The impairment of gait and postural stability was evaluated by a sum-score derived from the Unified Parkinson Disease Rating Scale.

RESULTS

Significant mean diffusivity increases, fractional anisotropy decreases and corresponding volume loss were localized in mesencephalic tegmentum, superior cerebellar peduncle, decussation of superior cerebellar peduncle and dentate nucleus in PSP-RS and PSP-P compared to PD and healthy controls. Altered microstructural integrity of the dentatorubrothalamic tract in PSP-RS was significantly more pronounced compared to PSP-P and correlated significantly with the gait and postural stability sum-score. Linear discriminant analysis identified diffusion tensor imaging measures of the dentatorubrothalamic tract and the gait and postural stability sum-score to classify correctly 95.5% of PRP-RS, PSP-P and PD patients.

CONCLUSIONS

Observer-independent analysis of microstructural integrity within the dentatorubrothalamic tract in combination with assessments of gait and postural stability differentiate PSP-P from PSP-RS and PD in early to moderately advanced stages.

Differentiation of neurodegenerative parkinsonian syndromes by volumetric magnetic resonance imaging analysis and support vector machine classification

BACKGROUND

Clinical differentiation of parkinsonian syndromes is still challenging.

OBJECTIVES

A fully automated method for quantitative MRI analysis using atlas-based volumetry combined with support vector machine classification was evaluated for differentiation of parkinsonian syndromes in a multicenter study.

METHODS

Atlas-based volumetry was performed on MRI data of healthy controls (n = 73) and patients with PD (204), PSP with Richardson's syndrome phenotype (106), MSA of the cerebellar type (21), and MSA of the Parkinsonian type (60), acquired on different scanners. Volumetric results were used as input for support vector machine classification of single subjects with leave-one-out cross-validation.

RESULTS

The largest atrophy compared to controls was found for PSP with Richardson's syndrome phenotype patients in midbrain (-15%), midsagittal midbrain tegmentum plane (-20%), and superior cerebellar peduncles (-13%), for MSA of the cerebellar type in pons (-33%), cerebellum (-23%), and middle cerebellar peduncles (-36%), and for MSA of the parkinsonian type in the putamen (-23%). The majority of binary support vector machine classifications between the groups resulted in balanced accuracies of >80%. With MSA of the cerebellar and parkinsonian type combined in one group, support vector machine classification of PD, PSP and MSA achieved sensitivities of 79% to 87% and specificities of 87% to 96%. Extraction of weighting factors confirmed that midbrain, basal ganglia, and cerebellar peduncles had the largest relevance for classification.

CONCLUSIONS

Brain volumetry combined with support vector machine classification allowed for reliable automated differentiation of parkinsonian syndromes on single-patient level even for MRI acquired on different scanners. © 2016 International Parkinson and Movement Disorder Society.

Brain gray matter abnormalities in progressive supranuclear palsy revisited

Whole-brain voxel-based morphometry (VBM) studies of progressive supranuclear palsy (PSP) have demonstrated heterogeneous findings regarding gray matter (GM) abnormalities. Here, we used Seed-based d Mapping, a coordinate-based meta-analytic approach to identify consistent regions of GM anomalies across studies of PSP. Totally, 18 original VBM studies, comprising 284 patients with PSP and 367 healthy controls were included. As compared to healthy controls, patients with PSP demonstrated significant GM reductions in both cortical and subcortical regions, including the frontal motor cortices, medial (including anterior cingulate cortex) and lateral frontal cortices, insula, superior temporal gyrus, striatum (putamen and caudate nucleus), thalamus, midbrain, and anterior cerebellum. Our study further suggests that many confounding factors, such as age, male ratio, motor severity, cognitive impairment severity, and illness duration of PSP patients, and scanner field-strength, could contribute to the heterogeneity of GM alterations in PSP across studies. Our comprehensive meta-analysis demonstrates a specific neuroanatomical pattern of GM atrophy in PSP with the involvement of the cortical-subcortical circuitries that mediate vertical supranuclear gaze palsy, motor disabilities (postural instability with falls and parkinsonism), and cognitive-behavioral disturbances. Confounding factors merit attention in future studies.

Magnetic resonance imaging for the diagnosis of Parkinson's disease

The differential diagnosis of parkinsonian syndromes is considered one of the most challenging in neurology and error rates in the clinical diagnosis can be high even at specialized centres. Despite several limitations, magnetic resonance imaging (MRI) has undoubtedly enhanced the diagnostic accuracy in the differential diagnosis of neurodegenerative parkinsonism over the last three decades. This review aims to summarize research findings regarding the value of the different MRI techniques, including advanced sequences at high- and ultra-high-field MRI and modern image analysis algorithms, in the diagnostic work-up of Parkinson's disease. This includes not only the exclusion of alternative diagnoses for Parkinson's disease such as symptomatic parkinsonism and atypical parkinsonism, but also the diagnosis of early, new onset, and even prodromal Parkinson's disease.

Radiological biomarkers for diagnosis in PSP: Where are we and where do we need to be?

PSP is a pathologically defined neurodegenerative tauopathy with a variety of clinical presentations including typical Richardson's syndrome and other variant PSP syndromes. A large body of neuroimaging research has been conducted over the past two decades, with many studies proposing different structural MRI and molecular PET/SPECT biomarkers for PSP. These include measures of brainstem, cortical and striatal atrophy, diffusion weighted and diffusion tensor imaging abnormalities, [18F] fluorodeoxyglucose PET hypometabolism, reductions in striatal dopamine imaging and, most recently, PET imaging with ligands that bind to tau. Our aim was to critically evaluate the degree to which structural and molecular neuroimaging metrics fulfill criteria for diagnostic biomarkers of PSP. We queried the PubMed, Cochrane, Medline, and PSYCInfo databases for original research articles published in English over the past 20 years using postmortem diagnosis or the NINDS-SPSP criteria as the diagnostic standard from 1996 to 2016. We define a five-level theoretical construct for the utility of neuroimaging biomarkers in PSP, with level 1 representing group-level findings, level 2 representing biomarkers with demonstrable individual-level diagnostic utility, level 3 representing biomarkers for early disease, level 4 representing surrogate biomarkers of PSP pathology, and level 5 representing definitive PSP biomarkers of PSP pathology. We discuss the degree to which each of the currently available biomarkers fit into this theoretical construct, consider the role of biomarkers in the diagnosis of Richardson's syndrome, variant PSP syndromes and autopsy confirmed PSP, and emphasize current shortfalls in the field. © 2017 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

A Fully Automated, Atlas-Based Approach for Superior Cerebellar Peduncle Evaluation in Progressive Supranuclear Palsy Phenotypes

BACKGROUND AND PURPOSE

The superior cerebellar peduncle is damaged in progressive supranuclear palsy. However, alterations differ between progressive supranuclear palsy with Richardson syndrome and progressive supranuclear palsy-parkinsonism. In this study, we propose an automated tool for superior cerebellar peduncle integrity assessment and test its performance in patients with progressive supranuclear palsy with Richardson syndrome, progressive supranuclear palsy-parkinsonism, Parkinson disease, and healthy controls.

MATERIALS AND METHODS

Structural and diffusion MRI was performed in 21 patients with progressive supranuclear palsy with Richardson syndrome, 9 with progressive supranuclear palsy-parkinsonism, 20 with Parkinson disease, and 30 healthy subjects. In a fully automated pipeline, the left and right superior cerebellar peduncles were first identified on MR imaging by using a tractography-based atlas of white matter tracts; subsequently, volume, mean diffusivity, and fractional anisotropy were extracted from superior cerebellar peduncles. These measures were compared across groups, and their discriminative power in differentiating patients was evaluated in a linear discriminant analysis.

RESULTS

Compared with those with Parkinson disease and controls, patients with progressive supranuclear palsy with Richardson syndrome showed alterations of all superior cerebellar peduncle metrics (decreased volume and fractional anisotropy, increased mean diffusivity). Patients with progressive supranuclear palsy-parkinsonism had smaller volumes than those with Parkinson disease and controls and lower fractional anisotropy than those with Parkinson disease. Patients with progressive supranuclear palsy with Richardson syndrome had significantly altered fractional anisotropy and mean diffusivity in the left superior cerebellar peduncle compared with those with progressive supranuclear palsy-parkinsonism. Discriminant analysis with the sole use of significant variables separated progressive supranuclear palsy-parkinsonism from progressive supranuclear palsy with Richardson syndrome with 70% accuracy and progressive supranuclear palsy-parkinsonism from Parkinson disease with 74% accuracy.

CONCLUSIONS

We demonstrate the feasibility of an automated approach for extracting multimodal MR imaging metrics from the superior cerebellar peduncle in healthy subjects and patients with parkinsonian. We provide evidence that structural and diffusion measures of the superior cerebellar peduncle might be valuable for computer-aided diagnosis of progressive supranuclear palsy subtypes and for differentiating patients with progressive supranuclear palsy-parkinsonism from with those with Parkinson disease.

Diagnostic value of blink reflex in multisystem atrophy, progressive supranuclear palsy and Parkinson disease

Abnormal blink reflex (BR) is a result of reticular brainstem pathways dysfunction and seems to be one of the features of brain degenerative disorders. The aim of the study was to estimate the diagnostic value of blink reflex in neurodegenerative diseases such as: multisystem atrophy (MSA), progressive supranuclear palsy (PSP) and Parkinson disease (PD). Material consisted of 99 patients with clinically probable MSA (51), PSP (28) and PD (20). MSA patients were divided into two subgroups, with dominant cerebellar (MSA-C) and parkinsonian signs (MSA-P). The mean age of patients was 64.9 years (47-79 years); males - 55.3%. Blink reflex was obtained in a typical way.

RESULTS

The significant differences in mean values of blink reflex latencies between PD and other subgroups (MSA-P, MSA-C, PSP) were found, but all of them were in normal range. In individual patients with PD and PSP (50% and 18%, respectively) delayed R2 latencies were recorded.

CONCLUSIONS

The most frequently abnormal blink reflexes, comparing the MSA, PSP and PD groups, were present in PD patients. We postulate that this may be explained by pathological influence of nigrostriatal pathway on the circuit linking the basal ganglia, cerebellum and brainstem.

Cognitive impairment in progressive supranuclear palsy-Richardson's syndrome is related to white matter damage

INTRODUCTION

Beside motor symptoms, patients with progressive supranuclear palsy syndrome (PSPs) commonly present cognitive and behavioral disorders. In this study we aimed to assess the structural brain correlates of cognitive impairment in PSPs.

METHODS

We enrolled 23 patients with probable PSP Richardson's syndrome and 15 matched healthy controls. Patients underwent an extensive clinical and neuropsychological evaluation. Cortical thickness measures and diffusion tensor metrics of white matter tracts were obtained. Random forest analysis was used to identify the strongest MRI predictors of cognitive impairment in PSPs at an individual patient level.

RESULTS

PSPs patients were in a moderate stage of the disease showing mild cognitive deficits with prominent executive dysfunction. Relative to controls, PSPs patients had a focal, bilateral cortical thinning mainly located in the prefrontal/precentral cortex and temporal pole. PSPs patients also showed a distributed white matter damage involving the main tracts including the superior cerebellar peduncle, corpus callosum, corticospinal tract, and extramotor tracts, such as the inferior fronto-occipital, superior longitudinal and uncinate fasciculi, and cingulum, bilaterally. Regional cortical thinning measures did not relate with cognitive features, while white matter damage showed a significant impact on cognitive impairment (r values ranging from -0.80 to 0.74).

CONCLUSIONS

PSPs patients show both focal cortical thinning in dorsolateral anterior regions and a distributed white matter damage involving the main motor and extramotor tracts. White matter measures are highly associated with cognitive deficits. Diffusion tensor MRI metrics are likely to be the most sensitive markers of extramotor deficits in PSPs.

Computer-based magnetic resonance imaging as a tool in clinical diagnosis in neurodegenerative diseases

Magnetic resonance imaging (MRI) is one of the core elements within the differential diagnostic work-up of patients with neurodegenerative diseases such as dementia syndromes, Parkinsonian syndromes, and motor neuron diseases. Currently, computerized MRI analyses are not routinely used for individual diagnosis; however, they have improved the anatomical understanding of pathomorphological alterations in various neurodegenerative diseases by quantitative comparisons between patients and controls at the group level. For multiparametric MRI protocols, including T1-weighted MRI, diffusion-weighted imaging, and intrinsic functional connectivity MRI, the potential as a surrogate marker is a subject of investigation. The additional value of MRI with respect to diagnosis at the individual level and for future disease-modifying multicentre trials remains to be defined. Here, we give an overview of recent applications of multiparametric MRI to patients with various neurodegenerative diseases. Starting from applications at the group level, continuous progress of a transfer to individual diagnostic classification is ongoing.

Charting Frontotemporal Dementia: From Genes to Networks

Frontotemporal dementia (FTD) is a genetically and clinically heterogeneous syndrome that is characterized by overlapping clinical symptoms involving behavior, personality, language and/or motor functions and degeneration of the frontal and temporal lobes. The term frontotemporal lobar degeneration (FTLD) is used to describe the proteinopathies associated with clinical FTD. Emerging evidence from network-based neuroimaging studies, such as resting state functional MRI and diffusion tensor MRI studies, have implicated specific large-scale brain networks in the pathogenesis of FTD syndromes, suggesting a new paradigm for explaining the distributed and heterogeneous spreading patterns of pathological proteins in FTLD. In this review, we overview recent research on the study of FTD syndromes as connectivity disorders in symptomatic patients as well as genotype-specific changes in asymptomatic FTD-related gene mutation carriers. Characterizing brain network breakdown in these subjects using neuroimaging may help anticipate the diagnosis and perhaps prevent the devastating impact of FTD.

Quantitative assessment of cerebral gray matter density change in progressive supranuclear palsy using voxel based morphometry analysis and cerebral MR T1-weighted FLAIR imaging

PURPOSE

To investigate the gray matter (GM) atrophy in Progressive supranuclear palsy (PSP) using T1-weighted Fluid-Attenuated Inversion Recovery (FLAIR) images based on voxel based morphometry (VBM) method.

MATERIALS AND METHODS

In this study, we firstly modified the conventional VBM method to make it can process the T1-weighted FLAIR brain images. Then, we used this method on the 24 PSP patients and 23 healthy age- and sex-matched control subjects to find the local gray matter density changes of PSP patients.

RESULTS

Compared with healthy controls, GM reductions of PSP patients mainly located in the thalamus, basal ganglia, pons, midbrain, insular cortex, frontal cortex, temporal lobe, cerebellum, cingulate cortex and hippocampus.

CONCLUSION

We used the modified VBM technique into T1 FLAIR data to study the brain gray matter atrophy in PSP, and found some new atrophy areas, including pallidum, middle and posterior cingulum, lingual, fusiform gyrus and the post part of inferior temporal gyrus. These areas have not been described in the former VBM studies, but they revealed abnormity in the pathologic and other studies on PSP. Our results might be expected to provide significant underlining neurology information and diagnostic value for PSP.

Neuroimaging evidence of gray and white matter damage and clinical correlates in progressive supranuclear palsy

To evaluate gray matter (GM) and white matter (WM) abnormalities and their clinical correlates in patients with progressive supranuclear palsy (PSP). Sixteen PSP patients and sixteen age-matched healthy subjects underwent a clinical evaluation and multimodal magnetic resonance imaging, including three-dimensional T1-weighted imaging and diffusion tensor imaging (DTI). Volumetric and DTI analyses were computed using SPM and FSL tools. PSP patients showed GM volume decrease, involving the frontal cortex, putamen, pallidum, thalamus and accumbens nucleus, cerebellum, and brainstem. Additionally, they had widespread changes in WM bundles, mainly affecting cerebellar peduncles, thalamic radiations, corticospinal tracts, corpus callosum, and longitudinal fasciculi. GM volumes did not correlate with WM abnormalities. DTI indices of WM damage, but not GM volumes, correlated with clinical scores of disease severity and cognitive impairment. The neurodegenerative changes that occur in PSP involve both GM and WM structures and develop concurrently though independently. WM damage in PSP correlates with clinical scores of disease severity and cognitive impairment, thus providing further insight into the pathophysiology of the disease.

Frontal corpus callosum alterations in progressive supranuclear palsy but not in Parkinson's disease

BACKGROUND

Frontal lobe involvement is considered a clinical and magnetic resonance imaging (MRI) feature in later stages of progressive supranuclear palsy (PSP).

OBJECTIVE

Diffusion tensor imaging (DTI) was used to investigate the integrity of frontal pathways in PSP and Parkinson's disease (PD) patients.

METHODS

DTI and 3-D MRI were performed in 15 PSP patients (parkinsonism subtype: n = 8; Richardson subtype: n = 7), 15 PD patients, and 18 matched controls. DTI analysis was performed in order to identify differences along frontal white matter structures including the corpus callosum (CC) and was complemented by atlas-based volumetry and planimetry.

RESULTS

Significantly reduced regional fractional anisotropy was observed for PSP patients versus controls and PSP versus PD patients, respectively, in frontal areas including the area II of the CC and bilaterally in the callosal radiation. The DTI findings correlated with frontal lobe volumes. These differences were not observed between PD patients and controls.

CONCLUSION

DTI identified a PSP-associated microstructural alteration pattern in the frontal lobes and in the CC area II including the corresponding bilateral callosal radiation tracts that could not be identified in both control samples, supporting the prominent PSP-associated frontal involvement as a potential neuroimaging marker.

Patterns of cerebellar volume loss in dementia with Lewy bodies and Alzheimer׳s disease: A VBM-DARTEL study

Evidence suggests that the cerebellum contributes to cognition as well as motor function. We investigated cerebellar grey matter (GM) and white matter (WM) changes from magnetic resonance images in dementia with Lewy bodies (DLB), Alzheimer׳s disease (AD) and healthy older subjects using voxel-based morphometry (VBM). Subjects (39 controls, 41 DLB, and 48 AD) underwent magnetic resonance imaging as well as clinical and cognitive assessments. VBM used SPM8 with a cerebellar brain mask to define the subspace for voxel analysis. Statistical analyses were conducted using the general linear model. Relative to findings in controls, VBM analysis revealed cerebellar GM loss in lobule VI bilaterally in AD and in left Crus I and right Crus II regions in DLB. WM deficits were confined to AD in the bilateral middle cerebellar peduncles. DLB demonstrates a different pattern of cerebellar GM loss which, although not significantly different from that in AD, could be an important feature in understanding the neurobiology of DLB and warrants further investigation.

Clinical outcomes of two main variants of progressive supranuclear palsy and multiple system atrophy: a prospective natural history study

Progressive supranuclear palsy (PSP) and parkinsonian subtype of multiple system atrophy (MSA-P) are, after Parkinson's disease (PD), the most common forms of neurodegenerative parkinsonism. Clinical heterogeneity of PSP includes two main variants, Richardson syndrome (PSP-RS) and PSP-parkinsonism (PSP-P). Clinical differentiation between them may be impossible at least during the first 2 years of the disease. Little is known about the differences in natural course of PSP-RS and PSP-P and, therefore, in this study we prospectively followed the clinical outcomes of consecutive, pathologically unconfirmed patients with the clinical diagnoses of PSP-RS (51 patients), PSP-P (21 patients) and MSA-P (49 patients). Estimated mean survival time was 11.2 years for PSP-P, 6.8 years for PSP-RS, and 7.9 years for MSA-P, where a 5-year survival probabilities were 90, 66 and 78 %, respectively. More disabling course of PSP-RS compared to PSP-P was also highlighted through the higher number of milestones reached in the first 3 years of the disease, as well as in the trend to reach all clinical milestones earlier. We found that PSP-P variant had a more favorable course with longer survival, not only when compared to PSP-RS, but also when compared to another form of atypical parkinsonism, MSA-P.

Clinical correlations of microstructural changes in progressive supranuclear palsy

In patients with progressive supranuclear palsy (PSP), previous reports have shown a severe white matter (WM) damage involving supra and infratentorial regions including cerebellum. In the present study, we investigated potential correlations between WM integrity loss and clinical-cognitive features of patients with PSP. By using magnetic resonance imaging and diffusion tensor imaging with tract based spatial statistic analysis, we analyzed WM volume in 18 patients with PSP and 18 healthy controls (HCs). All patients and HCs underwent a detailed clinical and neuropsychological evaluation. Relative to HCs, patients with PSP showed WM changes encompassing supra and infratentorial areas such as corpus callosum, fornix, midbrain, inferior fronto-occipital fasciculus, anterior thalamic radiation, superior cerebellar peduncle, superior longitudinal fasciculus, uncinate fasciculus, cingulate gyrus, and cortico-spinal tract bilaterally. Among different correlations between motor-cognitive features and WM structural abnormalities, we detected a significant association between fronto-cerebellar WM loss and executive cognitive impairment in patients with PSP. Our findings, therefore, corroborate the hypothesis that cognitive impairment in PSP may result from both "intrinsic" and "extrinsic" frontal lobe dysfunction, likely related to cerebellar disconnection.

The feasibility of white matter volume reduction analysis using SPM8 plus DARTEL for the diagnosis of patients with clinically diagnosed corticobasal syndrome and Richardson's syndrome

Purpose

Diagnosing corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP) is often difficult due to the wide variety of symptoms and overlaps in the similar clinical courses and neurological findings. The purpose of this study was to evaluate the utility of white matter (WM) atrophy for the diagnosis of patients with clinically diagnosed CBD (corticobasal syndrome, CBS) and PSP (Richardson’s syndrome, RS).

Methods

We randomly divided the 3D T1-weighted MR images of 18 CBS patients, 33 RS patients, and 32 age-matched controls into two groups. We obtained segmented WM images in the first group using Voxel-based specific regional analysis system for Alzheimer’s disease (VSRAD) based on statistical parametric mapping (SPM) 8 plus diffeomorphic anatomical registration through exponentiated Lie algebra. A target volume of interest (VOI) for disease-specific atrophy was subsequently determined in this group using SPM8 group analyses of WM atrophy between patients groups and controls. We then evaluated the utility of these VOIs for diagnosing CBS and RS patients in the second group. Z score values in these VOIs were used as the determinant in receiver operating characteristic (ROC) analyses.

Results

Specific target VOIs were determined in the bilateral frontal subcortical WM for CBS and in the midbrain tegmentum for RS. In ROC analyses, the target VOIs of CBS and RS compared to those of controls exhibited an area under curve (AUC) of 0.99 and 0.84, respectively, which indicated an adequate diagnostic power. The VOI of CBS revealed a higher AUC than that of RS for differentiating between CBS and RS (AUC, 0.75 vs 0.53).

Conclusions

Bilateral frontal WM volume reduction demonstrated a higher power for differentiating CBS from RS. This VOI analysis is useful for clinically diagnosing CBS and RS.

・We evaluate the utility of white matter (WM) atrophy for the diagnosis of patients with corticobasal syndrome (CBS) and Richardson’s syndrome (RS).

・We obtained segmented WM images using Voxel-based specific regional analysis system for Alzheimer’ s disease based on statistical parametric mapping 8 plus diffeomorphic anatomical registration through exponentiated Lie algebra.

・The most significant areas of atrophy observed in CBS patients compared to the controls were in the bilateral frontal subcortical WM.

・The most significant areas of atrophy observed in RS patients compared to the controls were in the midbrain.

・The volume of interest analysis using bilateral frontal WM volume reduction demonstrated a higher power for differentiating CBS from RS.

Voxelwise meta-analysis of gray matter anomalies in progressive supranuclear palsy and Parkinson's disease using anatomic likelihood estimation

Numerous voxel-based morphometry (VBM) studies on gray matter (GM) of patients with progressive supranuclear palsy (PSP) and Parkinson's disease (PD) have been conducted separately. Identifying the different neuroanatomical changes in GM resulting from PSP and PD through meta-analysis will aid the differential diagnosis of PSP and PD. In this study, a systematic review of VBM studies of patients with PSP and PD relative to healthy control (HC) in the Embase and PubMed databases from January 1995 to April 2013 was conducted. The anatomical distribution of the coordinates of GM differences was meta-analyzed using anatomical likelihood estimation. Separate maps of GM changes were constructed and subtraction meta-analysis was performed to explore the differences in GM abnormalities between PSP and PD. Nine PSP studies and 24 PD studies were included. GM reductions were present in the bilateral thalamus, basal ganglia, midbrain, insular cortex and inferior frontal gyrus, and left precentral gyrus and anterior cingulate gyrus in PSP. Atrophy of GM was concentrated in the bilateral middle and inferior frontal gyrus, precuneus, left precentral gyrus, middle temporal gyrus, right superior parietal lobule, and right cuneus in PD. Subtraction meta-analysis indicated that GM volume was lesser in the bilateral midbrain, thalamus, and insula in PSP compared with that in PD. Our meta-analysis indicated that PSP and PD shared a similar distribution of neuroanatomical changes in the frontal lobe, including inferior frontal gyrus and precentral gyrus, and that atrophy of the midbrain, thalamus, and insula are neuroanatomical markers for differentiating PSP from PD.

VBM Reveals Brain Volume Differences between Parkinson's Disease and Essential Tremor Patients

Symptoms of essential tremor (ET) are similar to those of Parkinson’s disease (PD) during their initial stages. Presently, there are few stable biomarkers available on a neuroanatomical level for distinguishing between these two diseases. However, few investigations have directly compared the changes in brain volume and assessed the compensatory effects of a change in the parts of the brain associated with PD and with ET. To determine the compensatory and/or degenerative anatomical changes in the brains of PD and ET patients, the present study tested, via two voxel-based morphometry (VBM) approaches (Basic vs. DARTEL VBM processing), the anatomical brain images of 10 PD and 10 ET patients, as well as of 13 age-matched normal controls, obtained through a 3T magnetic resonance scanner. These findings indicate that PD and ET caused specific patterns of brain volume alterations in the brains examined. In addition, our observations also revealed compensatory effects, or self-reorganization, occurring in the thalamus and the middle temporal gyrus in the PD and ET patients, due perhaps in part to the enhanced thalamocortical sensorimotor interaction and the head-eye position readjustment, respectively, in these PD and ET patients. Such a distinction may lend itself to use as a biomarker for differentiating between these two diseases.

Decreased brain volumes in manganese-exposed welders

BACKGROUND

A great deal of research has been devoted to identifying subclinical functional brain abnormalities in manganese (Mn)-exposed welders. However, no previous study has investigated morphological brain abnormalities, such as changes in brain volume, in welders. This study evaluates morphological changes in brain volume among welders, and investigates the relationship between structural brain abnormalities and subclinical dysfunction in this population.

METHODS

We used voxel-based morphometry (VBM) to assess differences in gray and white matter brain volumes between 40 welders with chronic Mn exposure and 26 age-matched control subjects. Correlation analyses were used to investigate the relationship between brain volume changes and decreased performance on neurobehavioral tests.

RESULTS

Brain volumes in the globus pallidus and cerebellar regions were significantly diminished in welders with chronic Mn exposure compared to controls (FDR-corrected P<0.05). These changes in brain volume were negatively correlated with cognitive performance and grooved pegboard scores.

CONCLUSION

There are measurable brain volume reductions in the globus pallidus and cerebellum of welders chronically exposed to Mn, and these volume reductions correlate with cognitive and motor neurobehavioral deficits. Our findings therefore indicate that volumetric measurement could be a useful subclinical marker among welders that show no signs of manganism.

Modeling trajectories of regional volume loss in progressive supranuclear palsy

Progressive supranuclear palsy is a neurodegenerative disease with progressive brain atrophy over time. It is unknown which specific brain regions decline over time, whether regional volume loss occurs in a linear fashion, and whether regional atrophy correlates with clinical decline over time in progressive supranuclear palsy. Twenty-eight subjects meeting probable progressive supranuclear palsy criteria were prospectively recruited and completed 96 MRI scans over 2 years. Mixed-effect models were utilized to determine which regions had significant atrophy over time and whether decline was linear or nonlinear. We assessed 13 regions across the brain, as well as whole-brain and ventricular volume. Regional trajectories were also correlated with change in clinical measures of executive function and gait and ocular motor impairment. A linear decline was observed in all frontal and temporal regions, the superior parietal lobe, the thalamus, the caudate nuclei, and the midbrain, as well as in the whole brain. Ventricular expansion was also linear. Nonlinear decline was observed for the caudal middle frontal lobe and globus pallidus. Rates of change in the superior frontal lobe, thalamus, and midbrain were beyond those expected in normal aging. Decline in frontal lobe volume and the midbrain area correlated best to decline in clinical measures. In progressive supranuclear palsy, atrophy is occurring in multiple brain regions, particularly in those that have previously been implicated in the disease. Decline is mainly linear but can be nonlinear for some regions. The frontal lobe and midbrain seem to be playing the most significant roles in the progressive worsening of clinical signs in progressive supranuclear palsy.

Clinical and cognitive correlations of regional gray matter atrophy in progressive supranuclear palsy

BACKGROUND

Progressive supranuclear palsy is the most common neurodegenerative bradykinetic-rigid syndrome after Parkinson's disease. Several volumetric studies have revealed a widespread cortical and subcortical gray matter atrophy, however the correlations between the pattern of gray matter loss and clinical-cognitive features have been poorly investigated.

METHODS

By using 3-T magnetic-resonance imaging and voxel-based morphometry we compared gray matter volume in 15 patients with progressive supranuclear palsy, 15 patients with Parkinson's disease and 15 healthy controls. All patients underwent a clinical and neuropsychological evaluation.

RESULTS

In agreement with previous studies, patients with progressive supranuclear palsy, compared to patients with Parkinson's disease and healthy controls, showed a reduced gray matter volume in several cortical and subcortical areas including cerebellum, frontal, temporal and parahippocampal cortical structures. We did not find any significant gray matter volume changes when comparing patients with Parkinson's disease vs healthy controls. Among different significant correlations between motor-cognitive features and gray matter loss, we detected a significant correlation between fronto-cerebellar gray matter atrophy and executive cognitive impairment in patients with progressive supranuclear palsy.

CONCLUSIONS

Our findings confirm that gray matter loss in patients with progressive supranuclear palsy involves several brain areas and suggest that cerebellar atrophy may play a role in the pathogenesis of cognitive dysfunction in patients with progressive supranuclear palsy due to a disruption of its modulation on executive functions.

Neuroimaging comparison of primary progressive apraxia of speech and progressive supranuclear palsy

BACKGROUND AND PURPOSE

Primary progressive apraxia of speech, a motor speech disorder of planning and programming, is a tauopathy that has overlapping histological features with progressive supranuclear palsy. We aimed to compare, for the first time, atrophy patterns, as well as white matter tract degeneration, between these two syndromes.

METHODS

Sixteen primary progressive apraxia of speech subjects were age- and gender-matched to 16 progressive supranuclear palsy subjects and 20 controls. All subjects were prospectively recruited, underwent neurological and speech evaluations and 3.0-Tesla magnetic resonance imaging. Grey and white matter atrophy was assessed using voxel-based morphometry and atlas-based parcellation, and white matter tract degeneration was assessed using diffusion tensor imaging.

RESULTS

All progressive supranuclear palsy subjects had typical oculomotor/gait impairments, but none had speech apraxia. Both syndromes showed grey matter loss in supplementary motor area, white matter loss in posterior frontal lobes and degeneration of the body of the corpus callosum. Whilst lateral grey matter loss was focal, involving superior premotor cortex, in primary progressive apraxia of speech, loss was less focal extending into prefrontal cortex in progressive supranuclear palsy. Caudate volume loss and tract degeneration of superior cerebellar peduncles were also observed in progressive supranuclear palsy. Interestingly, area of the midbrain was reduced in both syndromes compared to controls, although this was greater in progressive supranuclear palsy.

CONCLUSIONS

Although neuroanatomical differences were identified between these distinctive clinical syndromes, substantial overlap was also observed, including midbrain atrophy, suggesting these two syndromes may have common pathophysiological underpinnings.