Structural and Functional Brain Mapping Correlates of Impaired Eye Movement Control in Parkinsonian Syndromes: A Systems-Based Concept

Stepwise Functional Brain Architecture Correlates with Atrophy in Progressive Supranuclear Palsy

BACKGROUND

Stepwise functional connectivity (SFC) detects whole-brain functional couplings of a selected region of interest at increasing link-step topological distances.

OBJECTIVE

This study applied SFC to test the hypothesis that stepwise architecture propagating from the disease epicenter would shape patterns of brain atrophy in patients with progressive supranuclear palsy-Richardson's syndrome (PSP-RS).

METHODS

Thirty-six patients with PSP-RS and 44 age-matched healthy control subjects underwent brain magnetic resonance imaging on a 3-T scanner. The disease epicenter was defined as the peak of atrophy observed in an independent cohort of 13 cases with postmortem confirmation of PSP pathology and used as seed region for SFC analysis. First, we explored SFC rearrangements in patients with PSP-RS, as compared with age-matched control subjects. Subsequently, we tested SFC architecture propagating from the disease epicenter as a determinant of brain atrophy distribution.

RESULTS

The disease epicenter was identified in the left midbrain tegmental region. Compared with age-matched control subjects, patients with PSP-RS showed progressively widespread decreased SFC of the midbrain with striatal and cerebellar regions through direct connections and sensorimotor cortical regions through indirect connections. A correlation was found between average link-step distance from the left midbrain in healthy subjects and brain volumes in patients with PSP-RS (r = 0.38, P < 0.001).

CONCLUSIONS

This study provides comprehensive insights into the topology of functional network rearrangements in PSP-RS and demonstrates that the brain architectural topology, as described by SFC propagating from the disease epicenter, shapes the pattern of atrophic changes in PSP-RS. Our findings support the view of a network-based pathology propagation in this primary tauopathy. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Clinical value of video oculomotor evaluation in the differential diagnosis of multiple system atrophy and Parkinson's disease

BACKGROUND

Multiple system atrophy (MSA) is a neurodegenerative disease that progresses rapidly and has a poor prognosis. This study aimed to assess the value of video oculomotor evaluation (VOE) in the differential diagnosis of MSA and Parkinson's disease (PD).

METHODS

In total, 28 patients with MSA, 31 patients with PD, and 30 age- and sex-matched healthy controls (HC) were screened and included in this study. The evaluation consisted of a gaze-holding test, smooth pursuit eye movement (SPEM), random saccade, and optokinetic nystagmus (OKN).

RESULTS

The MSA and PD groups had more abnormalities and decreased SPEM gain than the HC group (64.29%, 35.48%, 10%, p < .001). The SPEM gain in the MSA group was significantly lower than that in the PD group at specific frequencies. Patients with MSA and PD showed prolonged latencies in all saccade directions compared with those with HC. However, the two diseases had no significant differences in the saccade parameters. The OKN gain gradually decreased from the HC to the PD and the MSA groups (p < .05). Compared with the PD group, the gain in the MSA group was further decreased in the OKN test at 30°/s (Left, p = .010; Right p = .016). Receiver operating characteristic curves showed that the combination of oculomotor parameters with age and course of disease could aid in the differential diagnosis of patients with MSA and PD, with a sensitivity of 89.29% and a specificity of 70.97%.

CONCLUSIONS

The combination of oculomotor parameters and clinical data may aid in the differential diagnosis of MSA and PD. Furthermore, VOE is vital in the identification of neurodegenerative diseases.

Automatic Analysis of MRI Images for Early Prediction of Alzheimer's Disease Stages Based on Hybrid Features of CNN and Handcrafted Features

Alzheimer's disease (AD) is considered one of the challenges facing health care in the modern century; until now, there has been no effective treatment to cure it, but there are drugs to slow its progression. Therefore, early detection of Alzheimer's is vital to take needful measures before it develops into brain damage which cannot be treated. Magnetic resonance imaging (MRI) techniques have contributed to the diagnosis and prediction of its progression. MRI images require highly experienced doctors and radiologists, and the analysis of MRI images takes time to analyze each slice. Thus, deep learning techniques play a vital role in analyzing a huge amount of MRI images with high accuracy to detect Alzheimer's and predict its progression. Because of the similarities in the characteristics of the early stages of Alzheimer's, this study aimed to extract the features in several methods and integrate the features extracted from more than one method into the same features matrix. This study contributed to the development of three methodologies, each with two systems, with all systems aimed at achieving satisfactory accuracy for the detection of AD and predicting the stages of its progression. The first methodology is by Feed Forward Neural Network (FFNN) with the features of GoogLeNet and DenseNet-121 models separately. The second methodology is by FFNN network with combined features between GoogLeNet and Dense-121 models before and after high-dimensionality reduction of features using the Principal Component Analysis (PCA) algorithm. The third methodology is by FFNN network with combined features between GoogLeNet and Dense-121 models separately and features extracted by Discrete Wavelet Transform (DWT), Local Binary Pattern (LBP) and Gray Level Co-occurrence Matrix (GLCM) methods called handcrafted features. All systems yielded super results in detecting AD and predicting the stages of its progression. With the combined features of the DenseNet-121 and handcrafted, the FFNN achieved an accuracy of 99.7%, sensitivity of 99.64%, AUC of 99.56%, precision of 99.63%, and a specificity of 99.67%.

Response times for reflexive saccades correlate with cognition in parkinson's disease, not disease severity or duration

Objective

Dementia is a common and serious non-motor symptom in Parkinson's disease (PD). We aimed to investigate the reflexive saccade in PD patients and explore its potential role as a biomarker for cognitive decline.

Methods

Using an infrared video-based eye tracker, we investigated reflexive saccades in 94 PD patients and 115 healthy controls (HCs). Saccadic parameters were compared between PD patients and HCs, and also among PD subgroups. The correlation of saccadic performance with disease duration, severity and cognition were further investigated.

Results

Compared with healthy controls, PD patients had prolonged and hypometric reflexive saccades even in early disease stage. Univariate and multivariate analysis showed that there was significant inverse relation between prolonged latency and MMSE in PD patients (P &lt; 0.05); tremor dominant PD patients were more likely to have decreased velocity than non-tremor-dominant PD patients (P &lt; 0.05); saccadic accuracy was found to have no significant relation with disease duration, H&amp;Y staging or MMSE.

Conclusion

Reflexive saccadic performance was abnormal in PD and worsened with cognitive decline. The negative correlation between prolonged latency and MMSE scores may make the reflexive saccade a potential predictor for cognitive decline in Parkinson's disease.

Impaired Ocular Tracking and Cortical Atrophy in Idiopathic Rapid Eye Movement Sleep Behavior Disorder

BACKGROUND

Idiopathic rapid eye movement sleep behavior disorder (iRBD) is a prodromal stage of synucleinopathies. Patients with synucleinopathies frequently display eye movement abnormalities. However, whether patients with iRBD have eye movement abnormalities remains unknown.

OBJECTIVE

The aim of this study was to assess eye movement abnormalities and related gray matter alterations and explore whether such abnormalities can serve as biomarkers to indicate phenoconversion to synucleinopathies in iRBD.

METHODS

Forty patients with iRBD with early disease progression and 35 healthy control subjects participated in a 15-minute ocular-tracking task that evaluated their control of eye movement abilities. They also underwent clinical assessments for olfactory function, nonmotor symptoms, and autonomic symptoms, all of which are biomarkers to predict phenoconversion to synucleinopathies in iRBD. A subgroup of the participants (20 patients with iRBD and 20 healthy control subjects) also participated in structural magnetic resonance imaging.

RESULTS

The ocular-tracking ability in patients with iRBD was inferior to that of healthy control subjects in two aspects: pursuit initiation and steady-state tracking. Cortical thinning in the right visual area V4 in patients with iRBD is coupled with impaired pursuit initiation. Furthermore, prolonged pursuit initiation in patients with iRBD exhibits a trend of correlation with olfactory loss, the earliest biomarker that develops prior to other prodromal biomarkers.

CONCLUSIONS

We found ocular-tracking abnormalities in patients with iRBD even early in their disease progression that have not been reported before. These abnormalities are coupled with atrophy of brain areas involved in the perception of object motion and might indicate phenoconversion to synucleinopathies in iRBD. © 2022 International Parkinson and Movement Disorder Society.

The differential diagnostic value of a battery of oculomotor evaluation in Parkinson's Disease and Multiple System Atrophy

INTRODUCTION

Clinical diagnosis of Parkinsonism is still challenging, and the diagnostic biomarkers of Multiple System Atrophy (MSA) are scarce. This study aimed to investigate the diagnostic value of the combined eye movement tests in patients with Parkinson's disease (PD) and those with MSA.

METHODS

We enrolled 96 PD patients, 33 MSA patients (18 with MSA-P and 15 with MSA-C), and 40 healthy controls who had their horizontal ocular movements measured. The multiple-step pattern of memory-guided saccade (MGS), the hypometria/hypermetria of the reflexive saccade, the abnormal saccade in smooth pursuit movement (SPM), gaze-evoked nystagmus, and square-wave jerks in gaze-holding test were qualitatively analyzed. The reflexive saccadic parameters and gain of SPM were also quantitatively analyzed.

RESULTS

The MGS test showed that patients with either diagnosis had a significantly higher incidence of multiple-step pattern compared with controls (68.6%, 65.2%, and versus. 2.5%, p < .05, in PD, MSA, versus. controls, respectively). The reflexive saccade test showed that MSA patients showing a prominent higher incidence of the abnormal saccade (63.6%, both hypometria and hypermetria) than that of PD patients and controls (33.3%, 7.5%, respectively, hypometria) (p < .05). The SPM test showed PD patients had mildly decreased gain among whom 28.1% presenting "saccade intrusions"; and that MSA patients had the significant decreased gain with 51.5% presenting "catch-up saccades"(p < .05). Only MSA patients showed gaze-evoked nystagmus (24.2%), square-wave jerks (6.1%) in gaze-holding test (p < .05).

CONCLUSIONS

A panel of eye movements tests may help to differentiate PD from MSA. The combined presence of hypometria and hypermetria in saccadic eye movement, the impaired gain of smooth pursuit movement with "catch-up saccades," gaze-evoked nystagmus, square-wave jerks in gaze-holding test, and multiple-step pattern in MGS may provide clues to the diagnosis of MSA.

Abnormal eye movements in parkinsonism: a historical view

Parkinson's disease (PD), known since ancient times as paralysis agitans, was studied and described by James Parkinson in 1817 in his work "An Essay on the Shaking Palsy". Fifty years later, Charcot and his students delved into the disease, naming it as we know it today, as well as defining the classic disease and its variants. One of these students, Arthur Dutil, addressed patients' abnormal eye movements. Nowadays, it is known that the differential diagnosis of PD is relevant for prognosis, treatment and research, and, despite the advances in the area, it remains largely clinical. The relevance of the eye movement exam has grown along with the history of PD and it has proved to be an excellent tool for the differential diagnosis of parkinsonism. Additionally, it can become a support to identify different types of genetic PD and be useful for improving early recognition of cognitive decline in patients with PD.

Analysis of Features of Alzheimer's Disease: Detection of Early Stage from Functional Brain Changes in Magnetic Resonance Images Using a Finetuned ResNet18 Network

One of the first signs of Alzheimer's disease (AD) is mild cognitive impairment (MCI), in which there are small variants of brain changes among the intermediate stages. Although there has been an increase in research into the diagnosis of AD in its early levels of developments lately, brain changes, and their complexity for functional magnetic resonance imaging (fMRI), makes early detection of AD difficult. This paper proposes a deep learning-based method that can predict MCI, early MCI (EMCI), late MCI (LMCI), and AD. The Alzheimer's Disease Neuroimaging Initiative (ADNI) fMRI dataset consisting of 138 subjects was used for evaluation. The finetuned ResNet18 network achieved a classification accuracy of 99.99%, 99.95%, and 99.95% on EMCI vs. AD, LMCI vs. AD, and MCI vs. EMCI classification scenarios, respectively. The proposed model performed better than other known models in terms of accuracy, sensitivity, and specificity.

Diagnostic value of video-oculography in progressive supranuclear palsy: a controlled study in 100 patients

Background

The eponymous feature of progressive supranuclear palsy (PSP) is oculomotor impairment which is one of the relevant domains in the Movement Disorder Society diagnostic criteria.

Objective

We aimed to investigate the value of specific video-oculographic parameters for the use as diagnostic markers in PSP.

Methods

An analysis of video-oculography recordings of 100 PSP patients and 49 age-matched healthy control subjects was performed. Gain of smooth pursuit eye movement and latency, gain, peak eye velocity, asymmetry of downward and upward velocities of saccades as well as rate of saccadic intrusions were analyzed.

Results

Vertical saccade velocity and saccadic intrusions allowed for the classification of about 70% and 56% of the patients, respectively. By combining both parameters, almost 80% of the PSP patients were covered, while vertical velocity asymmetry was observed in approximately 34%. All parameters had a specificity of above 95%. The sensitivities were lower with around 50–60% for the velocity and saccadic intrusions and only 27% for vertical asymmetry.

Conclusions

In accordance with oculomotor features in the current PSP diagnostic criteria, video-oculographic assessment of vertical saccade velocity and saccadic intrusions resulted in very high specificity. Asymmetry of vertical saccade velocities, in the opposite, did not prove to be useful for diagnostic purposes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-021-10522-9.