Brain magnetic resonance imaging (MRI) in parkinsonian disorders

Differentiating Between Low- and High-grade Glioma Tumors Measuring Apparent Diffusion Coefficient Values in Various Regions of the Brain

Objectives

Our study aimed to apply the apparent diffusion coefficient (ADC) values to quantify the differences between low- and high-grade glioma tumors.

Methods

We conducted a multicenter, retrospective study between September to December 2019. Magnetic resonance imaging (MRI) diffusion-weighted images (DWIs), and the pathologic findings of 56 patients with glioma tumors (low grade = 28 and high grade = 28) were assessed to measure the ADC values in the tumor center, tumor edema, boundary area between tumor with normal tissue, and inside the healthy hemisphere. These values were compared between the two groups, and cut-off values were calculated using the receiver operating characteristic curve.

Results

We saw significant differences between the mean ADC values measured in the tumor center and edema between high- and low-grade tumors (p< 0.005). The ADC values in the boundary area between tumors with normal tissue and inside healthy hemisphere did not significantly differ in the groups. The ADC values at tumor center and edema were higher than 1.12 × 10^-3 mm²/s (sensitivity = 100% and specificity = 96.0%) and 1.15 × 10^-3 mm²/s (sensitivity = 75.0% and specificity = 64.0%), respectively, could be classified as low-grade tumors.

Conclusions

The ADC values from the MRI DWIs in the tumor center and edema could be used as an appropriate method for investigating the differences between low- and high-grade glioma tumors. The ADC values in the boundary area and healthy tissues had no diagnostic values in grading the glioma tumors.

A Computational Study of Executive Dysfunction in Amyotrophic Lateral Sclerosis

Executive dysfunction is a well-documented, yet nonspecific corollary of various neurological diseases and psychiatric disorders. Here, we applied computational modeling of latent cognition for executive control in amyotrophic lateral sclerosis (ALS) patients. We utilized a parallel reinforcement learning model of trial-by-trial Wisconsin Card Sorting Test (WCST) behavior. Eighteen ALS patients and 21 matched healthy control participants were assessed on a computerized variant of the WCST (cWCST). ALS patients showed latent cognitive symptoms, which can be characterized as bradyphrenia and haphazard responding. A comparison with results from a recent computational Parkinson's disease (PD) study (Steinke et al., 2020, J Clin Med) suggests that bradyphrenia represents a disease-nonspecific latent cognitive symptom of ALS and PD patients alike. Haphazard responding seems to be a disease-specific latent cognitive symptom of ALS, whereas impaired stimulus-response learning seems to be a disease-specific latent cognitive symptom of PD. These data were obtained from the careful modeling of trial-by-trial behavior on the cWCST, and they suggest that computational cognitive neuropsychology provides nosologically specific indicators of latent facets of executive dysfunction in ALS (and PD) patients, which remain undiscoverable for traditional behavioral cognitive neuropsychology. We discuss implications for neuropsychological assessment, and we discuss opportunities for confirmatory computational brain imaging studies.

Quantitative Validation of a Visual Rating Scale for Defining High-Iron Putamen in Patients With Multiple System Atrophy

Objectives: To validate a visual rating scale reflecting sub-regional patterns of putaminal hypointensity in susceptibility-weighted imaging of patients with multiple system atrophy (MSA).

Methods: Using a visual rating scale (from G0 to G3), 2 examiners independently rated putaminal hypointensities of 37 MSA patients and 21 control subjects. To investigate the correlation with the scales, R2^* values and the volume of the entire putamen were measured.

Results: MSA patients with parkinsonian variant had significantly higher scores than those with cerebellar variant. Visual rating scores in MSA were correlated with R2^* values [General estimating equation (GEE), Wald chi-square = 25.89, corrected p < 0.001] and volume (Wald chi-square = 75.44, corrected p < 0.001). They correlated with UPDRS motor scores. Binary logistic regression analyses revealed that the visual rating scale was a significant predictor for discriminating MSA patients from controls [multivariate model adjusted for age and sex, odds ratio 52.722 (corrected p = 0.009)]. Pairwise comparison between areas under the curve (AUCs) revealed that the visual rating scale demonstrated higher accuracy than R2^* values [difference between AUCs; univariate model = 0.247 (corrected p < 0.001); multivariate model = 0.186 (corrected p = 0.003)]. There were no significant differences in clinical characteristics between the high-iron group, defined as putamen with visual rating scale ≥ G2 and R2^* values ≥ third quartile, and the remaining patients.

Conclusion: The visual rating scale, which reflects quantitative iron content and atrophy of the putamen as well as motor severities, could be useful for the discrimination and evaluation of patients with MSA.

[Cognitive impairment in patients with metabolic syndrome. The current treatment possibilities]

AIM

To study the effect of therapy with cytoflavin on cognitive function in patients with metabolic syndrome (MS).

MATERIAL AND METHODS

The randomized controlled open study included 156 patients with MS. The mean age was 41.27±5.16 years. The duration of observation was 16 weeks. The main group of patients (n=78) received cytoflavin in the dose of 2 tablets 2 times a day. Patients in the control group (n=78) received basic therapy. All patients underwent neuropsychological testing at baseline, after 2 months and at the end of the study. Cognitive evoked potentials (Р300) were recorded to assess cognitive functions. The levels of plasma glucose and lipid profile were measured.

RESULTS

Cytoflavin improved cognitive functions. Two months after treatment, the results of neuropsychological testing and electrophysiological study were better in the main group compared to the control group.

Cognitive and behavioural dysfunctions in a patient with progressive supranuclear palsy (PSP)

Background

The aim of the case study was to describe the profile of cognitive and emotional functioning of a patient with possible progressive supranuclear palsy (PSP) from a longitudinal perspective.

Participants and procedure

This study involved an 71-year-old male patient diagnosed with PSP, and 9 matched healthy subjects. Neuro-psychological examination of the patient was performed twice with a 6 month interval. A set of neuropsycho-logical tests was used to assess both cognition and behaviour.

Results

Neuropsychological assessment revealed executive dysfunction dominance (planning deficits, reduced cogni-tive flexibility and abstract thinking, impulsiveness), reduced verbal fluency, psychomotor slowness and prob-lems with memory retrieval from the long-term memory storage in contrast to significantly better recognition of the previously learned information. According to emotional functioning, frontal change of personality was ob-served, with apathy, disinhibition, lack of insights, impulsiveness and “utilization behaviours”.

Conclusions

The profile of emotional and cognitive impairments met the criteria for dementia. There was a progression of deficits at visit two in comparison to visit one. The longitudinal perspective allowed the dynamics of emotional, cognitive and behavioural changes to be described over time: from depression related to initially preserved criticism of the illness to apathy and emotional blunting and behavioural frontal syndrome connected with the systematic loss of insight.

Differential Diagnosis Of Multiple-System Atrophy With Parkinson's Disease By External Anal- And Urethral-Sphincter Electromyography

BACKGROUND

The differential diagnosis of Parkinson's disease (PD) with multiple-system atrophy (MSA) is difficult because of their similarity in symptoms and signs. The objective of this study was to investigate the value of external anal-sphincter electromyography (EAS-EMG) and urethral-sphincter electromyography (US-EMG) in differentiating MSA from PD.

METHODS

A total of 201 patients, - 101 MSA and 100 PD - were recruited in this study. Average duration and amplitude of motor unit potentials (MUPs), percentage of polyphasic MUPs, amplitude during strong contractions, and recruitment patterns during maximal voluntary contractions were recorded and analyzed to assess diagnostic efficiency of EAS-EMG and US-EMG for MSA.

RESULTS

Significant differences in average MUP duration and recruitment patterns during maximal voluntary contractions were found between patients with MSA and patients with PD using both EAS-EMG (P<0.001, P<0.001) and US-EMG (P<0.001, P<0.001). The percentage of polyphasic MUPs and amplitude during strong contractions showed significant differences in MSA and PD using only EAS-EMG (P<0.001, P=0.005). Cutoff points for average MUP duration in EAS-EMG and US-EMG for differential diagnosis of MSA with PD were 10.9 and 11.1 milliseconds, respectively. With average MUP duration of EAS-EMG and US-EMG being applied jointly, sensitivity and specificity in distinguishing MSA from PD were 83.2% and 71.8%, respectively.

CONCLUSION

EAS-EMG and US-EMG were sensitive and specific methods for the diagnosis and differential diagnosis of MSA, and the combination of both would improve the diagnostic rate of MSA compared to only one method being used.

Spatial correlation and segregation of multimodal MRI abnormalities in multiple system atrophy

OBJECTIVE

The variability of the severity and regional distribution of pathological process in basal ganglia (BG) and brainstem-cerebellar systems results in clinical heterogeneity and represents the motor subtype of multiple system atrophy (MSA). This study aimed to quantify spatial patterns of multimodal MRI abnormalities in BG and stem-CB regions and define structural MRI findings that correlate with clinical characteristics.

METHODS

We simultaneously measured R2*, mean diffusivity (MD), and volume in the subcortical structures (BG, thalamus, brainstem-cerebellar regions) of 39 probable MSA and 22 control subjects. Principal component analysis (PCA) and structural equation modeling (SEM) were performed to show a model consisting of multiple inter-dependencies.

RESULTS

Structural MRI alterations were found to be significantly interrelated within BG as well as brainstem-cerebellar regions in MSA patients. PCA extracted four factors: three factors reflected alterations in R2*, MD and volume of the BG region including the caudate nucleus, putamen, and pallidum, and the remaining one factor represented degenerative changes in MD and volume of stem-CB region. In SEM, a latent variable reflecting brainstem-cerebellar degeneration did not show a significant correlation with the other latent variables associated with BG degeneration. Putaminal MD values and a PCA-driven factor reflecting MD values in the BG showed a significant correlation with UPDRS and UMSARS scores.

CONCLUSION

Multimodal structural MRI abnormalities in MSA appear to be segregated into BG and stem-CB-related factors that can be associated with the clinical phenotype and motor severity.

The role of neuroimaging in the diagnosis of the atypical parkinsonian syndromes in clinical practice

Atypical parkinsonian disorders (APD) are a heterogenous group of neurodegenerative diseases such as: progressive supranuclear palsy (PSP), multiple system atrophy (MSA), cortico-basal degeneration (CBD) and dementia with Lewy bodies (DLB). In all of them core symptoms of parkinsonian syndrome are accompanied by many additional clinical features not typical for idiopathic Parkinson's disease (PD) like rapid progression, gaze palsy, apraxia, ataxia, early cognitive decline, dysautonomia and usually poor response to levodopa therapy. In the absence of reliably validated biomarkers the diagnosis is still challenging and mainly based on clinical criteria. However, robust data emerging from routine magnetic resonance imaging (MRI) as well as from many advanced MRI techniques such as: diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI), magnetic resonance spectroscopy (MRS), voxel-based morphometry (VBM), susceptibility-weighted imaging (SWI) may help in differential diagnosis. The main aim of this review is to summarize briefly the most important and acknowledged radiological findings of conventional MRI due to its availability in standard clinical settings. Nevertheless, we present shortly other methods of structural (like TCS - transcranial sonography) and functional imaging (like SPECT - single photon emission computed tomography or PET - positron emission tomography) as well as some selected advanced MRI techniques and their potential future applications in supportive role in distinguishing APD.

Progression of subcortical atrophy and iron deposition in multiple system atrophy: a comparison between clinical subtypes

Magnetic resonance imaging (MRI) can be useful not only for the diagnosis of multiple system atrophy (MSA) itself, but also to distinguish between different clinical subtypes. This study aimed to investigate whether there are differences in the progression of subcortical atrophy and iron deposition between two variants of MSA. Two serial MRIs at baseline and follow-up were analyzed in eight patients with the parkinsonian variant MSA (MSA-P), nine patients with cerebellar variant MSA (MSA-C), and fifteen patients with Parkinson's disease (PD). The R2* values and volumes were calculated for the selected subcortical structures (caudate nucleus, putamen, globus pallidus, and thalamus) using an automated region-based analysis. In both volume and R2*, a higher rate of progression was identified in MSA-P patients. Volumetric analysis showed significantly more rapid progression of putamen and caudate nucleus in MSA-P than in MSA-C. With regard to R2* changes, a significant increase at follow-up and a higher rate of progression were identified in the putamen of MSA-P group compared to MSA-C and PD groups. This longitudinal study revealed different progression rates of MRI markers between MSA-P and MSA-C. Iron-related degeneration in the putamen may be more specific for MSA-P.

[MRI in dementia-type diseases]

Dementia-inducing conditions represent a leading cause of disability and are a major health concern in industrialized countries. The burden these conditions put on society is certain to rise in the context of an ever-increasing elderly population. As these conditions feature an insidious onset and overlapping clinical features, imaging is a powerful tool in refining the diagnosis and assessing the progression of dementing conditions. The radiologist needs to be aware of and be able to detect underlying pathologies which could be reversible. Furthermore, imaging is important not only in excluding other pathologies but also in improving diagnostic accuracy. This article presents the typical clinical presentations as well as magnetic resonance imaging (MRI) features of the degenerative and the non-degenerative causes of dementia. The focus is on the core knowledge for MRI diagnostics in dementing conditions and a brief presentation of the latest MRI techniques which may become a part of standard imaging protocols in the future.

Differentiating multiple-system atrophy from Parkinson's disease

The purpose of this review is to illustrate the differentiating features of multiple-system atrophy from Parkinson's disease at MRI. The various MRI sequences helpful in the differentiation will be discussed, including newer methods, such as diffusion tensor imaging, MR spectroscopy, and nuclear imaging.

The role of functional dopamine-transporter SPECT imaging in parkinsonian syndromes, part 1

SUMMARY

As we defeat infectious diseases and cancer, one of the greatest medical challenges facing us in the mid-21st century will be the increasing prevalence of degenerative disease. Those diseases, which affect movement and cognition, can be the most debilitating. Dysfunction of the extrapyramidal system results in increasing motor disability often manifest as tremor, bradykinesia, and rigidity. The common pathologic pathway of these diseases, collectively described as parkinsonian syndromes, such as Parkinson disease, multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration, and dementia with Lewy bodies, is degeneration of the presynaptic dopaminergic pathways in the basal ganglia. Conventional MR imaging is insensitive, especially in early disease, so functional imaging has become the primary method used to differentiate a true parkinsonian syndrome from vascular parkinsonism, drug-induced changes, or essential tremor. Unusually for a modern functional imaging technique, the method most widely used in European clinics depends on SPECT and not PET. This SPECT technique (described in the first of 2 parts) commonly reports dopamine-transporter function, with decreasing striatal uptake demonstrating increasingly severe disease.

MAGNETIC RESONANCE SPECTROSCOPY IN EVALUATION OF COGNITIVE FUNCTIONS IN PATIENTS WITH METABOLIC SYNDROME

Objective. To evaluate the role of magnetic resonance spectroscopy (MR-spectroscopy) in the study of cognitive functions in patients with metabolic syndrome (MS).

Design and methods. The study included patients with MS (10 patients without cognitive impairment and 11 subjects with cognitive dysfunction). All patients underwent neuropsychological testing, and cognitive evoked potential for the assessment of cognitive functions. Brain metabolism was studied by proton MR-spectroscopy.

Results. In patients with MS and cognitive impairment, and without cognitive dysfunction no morphological changes in the brain according to the magnetic resonance imaging (MRI) were found. According to MR-spectroscopy of the brain in patients with MS and cognitive dysfunction the metabolism impairment is primarily associated with the increase in lactate and inositol.

Conclusion. Indicators of neuropsychological testing, the cognitive evoked potential are associated with the violation of brain metabolism in patients with MS and cognitive impairment.

Topographical differences of brain iron deposition between progressive supranuclear palsy and parkinsonian variant multiple system atrophy

OBJECTIVE

There have been various studies showing increased iron levels in parkinsonian disorders. The purpose of this study was to demonstrate topographical differences of brain iron deposition between progressive supranuclear palsy (PSP) and the parkinsonian variant of multiple system atrophy (MSA-p) with SWI images.

METHODS

A total of 11 patients with PSP, 12 with MSA-p, 15 with Parkinson's disease (PD), and 20 age-matched healthy controls underwent SWI of the brain. Mean phase shift values of the red nucleus (RN), substantia nigra (SN), head of the caudate nucleus (CN), globus pallidus (GP), putamen (PUT), and thalamus (TH) were calculated and compared between groups. A voxel-based analysis of the processed SWI was performed to determine topographical differences of iron-related hypointense signals in PUT, GP, and TH.

RESULTS

Patients with PSP and MSA-p had significantly higher levels of iron deposition than control and PD groups. Comparing patients with PSP and MSA-p, differences were found in iron concentrations of the RN, SN, GP, and TH, which were higher in the PSP group. However, iron levels in the PUT were higher in the MSA group (p<0.05). The area under curve (AUC) indicated that the PUT was the most valuable nucleus in differentiating MSA-p from PSP and PD according to phase shift values (AUC=0.836). Meanwhile the GP (AUC=0.869) and TH (AUC=0.884) were the two most valuable nuclei in differentiating PSP from MSA-p and PD. Voxel-based analysis showed subregional differences in iron-related hypointense signals in the PUT, GP, and TH between MSA-p and PSP groups. Patients with MSA-p had significant increases of iron-related hypointense signals in the posterolateral PUT and adjacent lateral aspect of the GP, whereas the PSP group had increased hypodense signals in the anterior and medial aspects of the GP and TH.

CONCLUSION

Our data demonstrate that pathological iron accumulations are more prevalent and severe in PSP compared to MSA-p. The distribution of high-iron-content regions in this study reflects pathoanatomically relevant sites. This finding allows for the use of MRI-based brain iron mapping as a technique to indirectly identify pathological changes.

Clinical approach to Parkinson's disease: features, diagnosis, and principles of management

Parkinson's disease (PD) is one of the most common neurodegenerative disorders. The condition causes a heavy burden both on those affected, as well as their families. Accurate diagnosis is critical and remains founded on clinical grounds as no specific diagnostic test is available so far. The clinical picture of PD is typical in many instances; however, features distinguishing it from other disorders should be thoroughly sought. Monogenic forms of PD also have some distinctive characteristics in many cases. This text is a roadmap to accurate diagnosis in PD, as it approaches clinical features, diagnostic methodology, and leading differential diagnoses. Therapeutic issues are also briefly discussed.

Optical coherence tomography in parkinsonian syndromes

Background/Objective

Parkinson's disease (PD) and the atypical parkinsonian syndromes multiple system atrophy (MSA), progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS) are movement disorders associated with degeneration of the central nervous system. Degeneration of the retina has not been systematically compared in these diseases.

Methods

This cross-sectional study used spectral-domain optical coherence tomography with manual segmentation to measure the peripapillar nerve fiber layer, the macular thickness, and the thickness of all retinal layers in foveal scans of 40 patients with PD, 19 with MSA, 10 with CBS, 15 with PSP, and 35 age- and sex-matched controls.

Results

The mean paramacular thickness and volume were reduced in PSP while the mean RNFL did not differ significantly between groups. In PSP patients, the complex of retinal ganglion cell- and inner plexiform layer and the outer nuclear layer was reduced. In PD, the inner nuclear layer was thicker than in controls, MSA and PSP. Using the ratio between the outer nuclear layer and the outer plexiform layer with a cut-off at 3.1 and the additional constraint that the inner nuclear layer be under 46 µm, we were able to differentiate PSP from PD in our patient sample with a sensitivity of 96% and a specificity of 70%.

Conclusion

Different parkinsonian syndromes are associated with distinct changes in retinal morphology. These findings may serve to facilitate the differential diagnosis of parkinsonian syndromes and give insight into the degenerative processes of patients with atypical parkinsonian syndromes.

Patterns of focal gray matter atrophy are associated with bradykinesia and gait disturbances in older adults

OBJECTIVES

Identify the neuroimaging correlates of parkinsonian signs in older adults living in the community.

METHODS

Magnetic resonance imaging was obtained in 307 adults (82.9 years, 55% women, 39% blacks) concurrently with the Unified Parkinson Disease Rating scale-motor part. Magnetic resonance imaging measures included volume of whole-brain white matter hyperintensities and of gray matter for primary sensorimotor, supplementary motor, medial temporal areas, cerebellum, prefronto-parietal cortex, and basal ganglia.

RESULTS

About 25% of the participants had bradykinesia, 26% had gait disturbances, and 12% had tremor. Compared with those without, adults with any one of these signs were older, walked more slowly, had worse scores on tests of cognition, mood and processing speed, and higher white matter hyperintensities volume (all p ≤ .002). Gray matter volume of primary sensorimotor area was associated with bradykinesia (standardized odds ratio [95% confidence interval]: 0.46 [0.31, 0.68], p < .0001), and gray matter volume of medial temporal area was associated with gait disturbances (0.56 [0.42, 0.83], p < .0001), independent of white matter hyperintensities volume and age. Further adjustment for measures of muscle strength, cardiovascular health factors, cognition, processing speed, and mood or for gait speed did not substantially change these results.

CONCLUSIONS

Atrophy within primary sensorimotor and medial temporal areas might be important for development of bradykinesia and of gait disturbances in community-dwelling elderly adults. The pathways underlying these associations may not include changes in white matter hyperintensities volume, cognition, information processing speed, mood, or gait speed.

Voxel-based statistical analysis of fractional anisotropy and mean diffusivity in patients with unilateral temporal lobe epilepsy of unknown cause

PURPOSE

To determine regional alterations of fractional anisotropy (FA) and mean diffusivity (MD) in patients with magnetic resonance imaging (MRI)-negative temporal lobe epilepsy with unknown cause (TLEu) using diffusion tensor imaging (DTI) and voxel-based statistics (VBS).

METHODS

Ten patients with left TLEu and no abnormality on conventional MRI and 81 age-matched neurological healthy controls were studied. VBS analyses were used to compare FA and MD differences between patients and controls. All results were reported using stringent statistical thresholds corrected for multiple comparisons.

RESULTS

Patients with TLEu had widespread and bilateral reduction of white matter FA, encompassing the temporal lobes, entire corpus callosum, thalamus, and other regions relative to controls. Increased MD was more spatially limited in patients, but was also observed in the thalamus. FA of the putamen was significantly increased bilaterally in patients relative to controls, which correlated with increasing macroscopic atrophy of the putamen.

DISCUSSION

Water diffusion abnormalities are widespread and bilaterally distributed in patients with unilateral TLEu, which are beyond the resolution of conventional MRI. FA alterations are more widespread relative to MD alterations. This is the first study to show evidence of interrelated microscopic (ie, FA increase) and macroscopic (ie, atrophy) alterations of the putamen in patients with TLEu.

Advances in imaging in Parkinson's disease

Advances in imaging have made it possible to detect functional and, increasingly, structural changes in Parkinson's disease. Although imaging is not yet routinely used for diagnosis, such an application is becoming increasingly feasible. Of potentially greater interest, however, is the use of imaging as a biomarker to detect premotor disease and disease progression. Imaging also provides insights into complications of Parkinson's disease and its long-term treatment, and the role of dopamine in the normal brain. Furthermore, these techniques can be applied to animal models, to help validate these models and allow their use in the study of potential disease-modifying therapies.

Putaminal hypointensity in the parkinsonian variant of multiple system atrophy: simple visual assessment using susceptibility-weighted imaging

Background and Purpose

Susceptibility-weighted imaging (SWI) has been shown to be superior in its ability to demonstrate brain mineralization than other conventional MR imaging. The goal of our study was therefore to assess the frequency and extent of putaminal hypointensity in parkinsonian variant MSA using SWI.

Methods

11 patients with multiple system atrophy-parkinsonian type (MSA-p), 30 patients with Parkinson’s disease (PD), and age matched 30 controls were investigated using 3 Tesla MRI. The pattern of putaminal hypointensity was measured using a visual grading scale and scored from 0 to 3.

Results

Hemi- or bilateral putaminal hypointensity (a score of ≥ 2) and hyperintense rim were recognized in 81.8% and 54.5% of 11 MSA-p, respectively. The scores of putaminal hypointensity of MSA-p were significantly higher than other groups (p < 0.001), a score of ≥ 2 differentiated MSA-p from other groups. And all five patients with early disease stage also showed these characteristic findings.

Conclusions

SWI appears to be useful for depicting putaminal hypointensity even in early stage of MSA-p. This finding suggests that iron deposition associated putaminal degeneration can occur early in the disease process.

Microstructural and volumetric abnormalities of the putamen in juvenile myoclonic epilepsy

PURPOSE

Patients with juvenile myoclonic epilepsy (JME) show evidence of microstructural white matter (WM) damage of thalamocortical fiber tracts and changes of blood oxygen level dependent (BOLD) signal in a striatothalamocortical network. The objective of the present study was to investigate microstructural and volumetric alterations of the putamen in patients with JME using diffusion tensor imaging (DTI) and conventional magnetic resonance imaging (MRI).

METHODS

We performed DTI and MRI for 10 patients with JME and 59 age-matched neurologically healthy volunteers. Evaluation of microstructural damage was investigated using calculation of mean fractional anisotropy (FA) values in a priori regions of interest (ROIs) for the putamen, frontal lobe, and a thalamocortical region, after application of an improved eddy current correction method and a new statistical parametric mapping (SPM)-compatible toolbox incorporating intensive multicontrast FA image registration. Stereologic analysis on MRI was performed to estimate macroscopic volume of the putamen in both cerebral hemispheres for all subjects.

KEY FINDINGS

Relative to controls, patients had significantly reduced FA in the frontal lobe (p = 0.01) and thalamocortical fiber WM (p < 0.001). In contrast, putamen FA was bilaterally increased (p = 0.01) and correlated with decreasing putamen volume (r(2) = -0.63, p = 0.004) in patients only. Putamen FA correlated negatively with onset of JME (total: r(2) = -0.50, p = 0.01), duration of JME (r(2) = 0.52, p = 0.01), and thalamocortical fiber FA (r(2) = -0.47, p = 0.01).

SIGNIFICANCE

This is the first evidence of combined microstructural and macrostructural putamen abnormalities in patients with JME, with early age of onset and a longer duration of epilepsy being significant predictors for greater architectural alterations. These findings are consistent with studies indicating neurophysiologic abnormalities of frontostriatal networks in patients with JME, and may contribute to explain the frequent presentation of executive dysfunction in these patients. Confirmation and further exploration of the increase in putamen FA in patients with JME is required in larger samples.

Selective frontal neurodegeneration of the inferior fronto-occipital fasciculus in progressive supranuclear palsy (PSP) demonstrated by diffusion tensor tractography

Background

The clinical presentation in progressive supranuclear palsy (PSP), an atypical parkinsonian disorder, includes varying degrees of frontal dysexecutive symptoms. Using diffusion tensor imaging (DTI) and tractography (DTT), we investigated whether diffusion changes and atrophy of the inferior fronto-occipital fasciculus (IFO) occurs in PSP and if these changes correlate with disease stage and clinical phenotype. The corticospinal tract (CST), which is often involved in PSP, was investigated for comparison.

Methods

DTI of the whole brain was performed with a 3 T MR scanner using a single shot-EPI sequence with diffusion encoding in 48 directions. Scans were obtained in patients with PSP (n = 13) and healthy age-matched controls (n = 12). DTT of the IFO and CST was performed with the PRIDE fibre tracking tool (Philips Medical System). Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were calculated and correlated with disease stage and clinical phenotype.

Results

In patients with PSP, significantly decreased FA and increased ADC was found in the frontal part of IFO compared with the medial and occipital parts of IFO, as well as compared to controls. Four of the thirteen patients with PSP showed a marked decrease in the number of tracked voxels in the frontal part of IFO. These findings were most pronounced in patients with severe frontal cognitive symptoms, such as dysexecutive problems, apathy and personality change. There was a strong correlation (r² = -0.84; p < 0,001) between disease stage and FA and ADC values in the CST.

Conclusions

DTT for identification of neuronal tracts with subsequent measurement of FA and ADC is a useful diagnostic tool for demonstrating patterns of neuronal tract involvement in neurodegenerative disease. In selected tracts, FA and ADC values might act as surrogate markers for disease stage.

Reduction of neuromelanin-positive nigral volume in patients with MSA, PSP and CBD

OBJECTIVE

Diseases presenting extrapyramidal symptoms are accompanied by nigral cell loss. In the previous study, we demonstrated the reduction of the neuromelanin-positive volume of substantia nigra (SN) pars compacta (SNc) in patients with Parkinson's disease (PD) using 3-Tesla MRI. In the present study we investigated the neuromelanin-positive SNc volume in patients with the other parkinsonian disorders including multiple system atrophy (MSA), progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) and compared the results with those with PD, spinocerebellar ataxia (SCA) and controls.

PATIENTS AND METHODS

Axial T1-weighted (T1W) images were obtained with a 3-Tesla MRI scanner. The border of the neuromelanin-positive region of the SNc was traced manually on these images with a pentablet pointing device and the SNc volume was calculated. The SNc volumes of 28 patients with MSA, 11 patients with PSP and 10 patients with CBD were compared with those of 80 patients with PD, 9 patients with SCA and 54 patients who had suffered mild acute ischemic stroke as controls. The mean volumes for the left and right SN were used for statistical analyses.

RESULTS

The volumes of the neuromelanin-positive SNc region in patients with MSA, PSP and CBD, but not SCA were reduced to the same extent as PD patients compared with controls.

CONCLUSION

Reduced volume of the neuromelanin-positive SNc region of patients with MSA, PSP and CBD was detected by neuromelanin MR imaging. Volumetric evaluation of neuromelanin MR imaging may provide a biomarker of nigral degeneration in patients with MSA, PSP and CBD as in patients with PD.

Idiopathic Parkinson disease effect of levodopa on apparent diffusion coefficient value of the brain

PURPOSE

To evaluate the effect of levodopa on apparent diffusion coefficient (ADC) value of the brain parenchyma in patients with idiopathic Parkinson disease (PD).

MATERIAL AND METHODS

Prospective study was conducted on native PD without treatment (n = 25) and patients receiving levodopa (L-Dopa) (n = 25). Diffusion magnetic resonance-weighted imaging was done using a single-shot spin echo type of echo planar imaging. The apparent diffusion coefficient (ADC) value at different regions of the brain on both sides was calculated.

RESULTS

The ADC value of the putamen in patients with native PD was 0.732 ± 0.15 × 10-3 mm2/seconds and in patients receiving levodopa was 0.789 ± 0.24 × 10-3 mm2/second. There was a statistically significant difference in the ADC value at the putamen (P = .001) between patients with native PD and patients receiving levodopa. When ADC value of the putamen at 0.745 × 10-3 mm2/second was used as a threshold value for differentiating native PD patients and patients receiving L-Dopa, the best results were obtained with an accuracy of 82%, sensitivity of 92%, specificity of 72%, positive predictive value of 77%, negative predictive value of 90%, and area under the curve of 0.955.

CONCLUSION

ADC value of the putamen is a promising parameter for predication of effect of levodopa on brain parenchyma in patients with PD.

Biomarkers: Parkinson disease with dementia and dementia with Lewy bodies

Dementia is a common feature in Parkinson disease (PD), the time of onset determining how patients are classified. Those patients where dementia develops prior to parkinsonism or during the first year of disease are designated as having dementia with Lewy bodies (DLB). In those where dementia develops over a year after the onset of motor signs, the condition is known as Parkinson's disease with dementia (PDD). While this seems at first sight to be a definitive way to distinguish these conditions, reality is rather different. The overlap between them is considerable, and there is much uncertainty associated with patients who have both motor symptoms and early cognitive impairment. The diagnosis is still based on medical history and clinical evaluation. It is not even certain that they can be accurately distinguished at autopsy. For this reason, the data concerning these entities have been reviewed, to examine various markers employed or measured in clinical, neuropathological, neuroimaging, and biochemical investigations. The concept of PDD and DLB being separate conditions is comparatively new, and the most promising tools with which to separate them at present are cerebrospinal fluid (CSF) markers and positron emission tomography (PET) scanning that indicate increased amyloid-beta burden in DLB compared to PDD. However as yet there are no markers that unequivocally distinguish between PDD and DLB.

Characterizing iron deposition in Parkinson's disease using susceptibility-weighted imaging: an in vivo MR study

Brain-iron deposition has been proposed to play an important role in the pathophysiology of Parkinson's disease (PD). The aim of this study was to evaluate the feasibility of characterizing iron deposition in PD using susceptibility-weighted imaging (SWI), and to investigate the correlation of brain-iron accumulation with the clinical status in patients with PD. Forty patients with PD without dementia and 26 age- and sex-matched healthy controls underwent high-resolution susceptibility-weighted magnetic resonance (MR) imaging. The phase shift values of the bilateral red nucleus (RN), substantia nigra (SN), caudate nucleus (CA), globus pallidus (GP), putamen (PU), thalamus (TH) and frontal white matter (FWM) were examined for their relationship with the clinical status. The iron concentrations of the regions involved in PD, such as the SN, increased more significantly, while those in other regions of interest (ROI) did not elevate significantly. No correlation between the increase of the iron concentrations of the SN and duration of PD was observed. PD, however, was closely associated with the Unified Parkinson's Disease Rating Scale motor score (UPDRS-III). No significant differences were found between earlier-onset and later-onset PD patients in terms of the iron concentrations of the SN. Brain-iron concentration can be evaluated by SWI. Also, the brain-iron concentration in the SN correlated with UPDRS motor score, indicating that iron concentration can function as an in vivo biomarker to objectively evaluate the status of PD.

History of falls in Parkinson disease is associated with reduced cholinergic activity

OBJECTIVE

To investigate the relationships between history of falls and cholinergic vs dopaminergic denervation in patients with Parkinson disease (PD).

BACKGROUND

There is a need to explore nondopaminergic mechanisms of gait control as the majority of motor impairments associated with falls in PD are resistant to dopaminergic treatment. Alterations in cholinergic neurotransmission in PD may be implicated because of evidence that gait control depends on cholinergic system-mediated higher-level cortical and subcortical processing, including pedunculopontine nucleus (PPN) function.

METHODS

In this cross-sectional study, 44 patients with PD (Hoehn & Yahr stages I-III) without dementia and 15 control subjects underwent a clinical assessment and [(11)C]methyl-4-piperidinyl propionate (PMP) acetylcholinesterase (AChE) and [(11)C]dihydrotetrabenazine (DTBZ) vesicular monoamine transporter type 2 (VMAT2) brain PET imaging.

RESULTS

Seventeen patients (38.6%) reported a history of falls and 27 patients had no falls. Analysis of covariance of the cortical AChE hydrolysis rates demonstrated reduced cortical AChE in the PD fallers group (-12.3%) followed by the PD nonfallers (-6.6%) compared to control subjects (F = 7.22, p = 0.0004). Thalamic AChE activity was lower only in the PD fallers group (-11.8%; F = 4.36, p = 0.008). There was no significant difference in nigrostriatal dopaminergic activity between PD fallers and nonfallers.

CONCLUSIONS

Unlike nigrostriatal dopaminergic denervation, cholinergic hypofunction is associated with fall status in Parkinson disease (PD). Thalamic AChE activity in part represents cholinergic output of the pedunculopontine nucleus (PPN), a key node for gait control. Our results are consistent with other data indicating that PPN degeneration is a major factor leading to impaired postural control and gait dysfunction in PD.

Recent developments in multiple system atrophy

Multiple system atrophy (MSA) is a rare late onset neurodegenerative disorder which presents with autonomic failure and a complicated motor syndrome including atypical parkinsonism, ataxia and pyramidal signs. MSA is a glial alpha-synucleinopathy with rapid progression and currently poor therapeutic management. This paper reviews the clinical features, natural history and novel diagnostic criteria for MSA as well as contemporary knowledge on pathogenesis based on evidence from neuropathological studies and experimental models. An outline of the rationale for managing symptomatic deterioration in MSA is provided together with a summary of novel experimental therapeutic approaches to decrease disease progression.