Multiple system atrophy

Comparative Study between the Diagnostic Effectiveness of Brain SPECT with [123I]Ioflupane and [123I]MIBG Scintigraphy in Multiple System Atrophy

BACKGROUND

Multiple system atrophy (MSA) is a neurodegenerative disease. It has a fast progression, so early diagnosis is decisive. Two functional imaging tests can be involved in its diagnosis: [123I]Ioflupane SPECT and [123I]MIBG scintigraphy. Our aim is to comparatively analyze the diagnostic performance of both techniques.

METHODS

46 patients (24 males and 22 females) with MSA underwent [123I]Ioflupane SPECT and [123I]MIBG scintigraphy. In each of these techniques, qualitative assessment was compared with quantitative assessment.

RESULTS

SPECT visual assessment was positive in 93.5% of subjects (S = 95.24%; PPV = 93.02%). A cut-off of 1.363 was established for overall S/O index (S = 85.7%, E = 100%). Visual assessment of scintigraphy was positive in 73.1% (S = 78.57%, PPV = 94.29%). For the delayed heart/medistinum ratio (HMR) a cut-off of 1.43 (S = 85.3, E = 100%) was obtained. For each unit increase in delayed HMR, the suspicion of MSA increased by 1.58 (OR = 1.58, p < 0.05). The quantitative assessment showed an association with the visual assessment for each technique (p < 0.05).

CONCLUSIONS

Both tests are useful in MSA diagnosis. Comparatively, we did not observe a clear superiority of either. Striatal and myocardial deterioration do not evolve in parallel. Qualitative assessment is crucial in both techniques, together with the support of quantitative analysis. Delayed HMR shows a direct relationship with the risk of MSA.

Diagnostic Effectiveness of [123I]Ioflupane Single Photon Emission Computed Tomography (SPECT) in Multiple System Atrophy

BACKGROUND

Multiple system atrophy (MSA) is a rapidly progressive neurodegenerative disorder that has no curative treatment. Diagnosis is based on a set of criteria established by Gilman (1998 and 2008) and recently updated by Wenning (2022). We aim to determine the effectiveness of [¹²³I]Ioflupane SPECT in MSA, especially at the initial clinical suspicion.

METHODS

A cross-sectional study of patients at the initial clinical suspicion of MSA, referred for [¹²³I]Ioflupane SPECT.

RESULTS

Overall, 139 patients (68 men, 71 women) were included, 104 being MSA-probable and 35 MSA-possible. MRI was normal in 89.2%, while SPECT was positive in 78.45%. SPECT showed high sensitivity (82.46%) and positive predictive value (86.24), reaching maximum sensitivity in MSA-P (97.26%). Significant differences were found when relating both SPECT assessments in the healthy-sick and inconclusive-sick groups. We also found an association when relating SPECT to the subtype (MSA-C or MSA-P), as well as to the presence of parkinsonian symptoms. Lateralization of striatal involvement was detected (left side).

CONCLUSIONS

[¹²³I]Ioflupane SPECT is a useful and reliable tool for diagnosing MSA, with good effectiveness and accuracy. Qualitative assessment shows a clear superiority when distinguishing between the healthy-sick categories, as well as between the parkinsonian (MSA-P) and cerebellar (MSA-C) subtypes at initial clinical suspicion.

Mini-Review: The MSA transcriptome

Multiple system atrophy (MSA) is an atypical parkinsonism that rapidly affects motor ability and autonomic function, leaving patients wheelchair-bound and dependent for daily activities in 3-5 years. Differential diagnosis is challenging as cases may resemble Parkinson's disease or other ataxic syndromes depending on the clinical variant (MSA-P or MSA-C), especially in early stages. There are limited symptomatic treatments and no disease-modifying therapies. Pathologically, alpha-synuclein aggregates are found in glial cytoplasmic inclusions, among other proteins, as well as in neurons. The molecular pathogenesis of the disease, however, is widely unknown. Transcriptomic studies in MSA have tried to unravel the pathological mechanisms involved in the disease. Several biological and molecular processes have been described in the literature that associate disease pathogenesis with inflammation, mitochondrial, and autophagy related dysfunctions, as well as prion disease and Alzheimer disease associated pathways. These reports have also registered several differential diagnostic biomarker candidates. However, cross-validation between studies, in general, is poor, making clinical applicability and data reliability very challenging. This review will go over the main transcriptomic studies done in MSA, reporting on the most significant transcriptive and post-transcriptive changes described, and focusing on the main consensual findings.

Transcriptomic differences in MSA clinical variants

Background: Multiple system atrophy (MSA) is a rare oligodendroglial synucleinopathy of unknown etiopathogenesis including two major clinical variants with predominant parkinsonism (MSA-P) or cerebellar dysfunction (MSA-C). Objective: To identify novel disease mechanisms we performed a blood transcriptomic study investigating differential gene expression changes and biological process alterations in MSA and its clinical subtypes. Methods: We compared the transcriptome from rigorously gender and age-balanced groups of 10 probable MSA-P, 10 probable MSA-C cases, 10 controls from the Catalan MSA Registry (CMSAR), and 10 Parkinson Disease (PD) patients. Results: Gene set enrichment analyses showed prominent positive enrichment in processes related to immunity and inflammation in all groups, and a negative enrichment in cell differentiation and development of the nervous system in both MSA-P and PD, in contrast to protein translation and processing in MSA-C. Gene set enrichment analysis using expression patterns in different brain regions as a reference also showed distinct results between the different synucleinopathies. Conclusions: In line with the two major phenotypes described in the clinic, our data suggest that gene expression and biological processes might be differentially affected in MSA-P and MSA-C. Future studies using larger sample sizes are warranted to confirm these results.

Transcriptional profiling of multiple system atrophy cerebellar tissue highlights differences between the parkinsonian and cerebellar sub-types of the disease

Multiple system atrophy (MSA) is a rare adult-onset neurodegenerative disease of unknown cause, with no effective therapeutic options, and no cure. Limited work to date has attempted to characterize the transcriptional changes associated with the disease, which presents as either predominating parkinsonian (MSA-P) or cerebellar (MSC-C) symptoms. We report here the results of RNA expression profiling of cerebellar white matter (CWM) tissue from two independent cohorts of MSA patients (n = 66) and healthy controls (HC; n = 66). RNA samples from bulk brain tissue and from oligodendrocytes obtained by laser capture microdissection (LCM) were sequenced. Differentially expressed genes (DEGs) were obtained and were examined before and after stratifying by MSA clinical sub-type.We detected the highest number of DEGs in the MSA-C group (n = 747) while only one gene was noted in MSA-P, highlighting the larger dysregulation of the transcriptome in the MSA-C CWM. Results from both bulk tissue and LCM analysis showed a downregulation of oligodendrocyte genes and an enrichment for myelination processes with a key role noted for the QKI gene. Additionally, we observed a significant upregulation of neuron-specific gene expression in MSA-C and enrichment for synaptic processes. A third cluster of genes was associated with the upregulation of astrocyte and endothelial genes, two cell types with a key role in inflammation processes. Finally, network analysis in MSA-C showed enrichment for β-amyloid related functional classes, including the known Alzheimer's disease (AD) genes, APP and PSEN1.This is the largest RNA profiling study ever conducted on post-mortem brain tissue from MSA patients. We were able to define specific gene expression signatures for MSA-C highlighting the different stages of the complex neurodegenerative cascade of the disease that included alterations in several cell-specific transcriptional programs. Finally, several results suggest a common transcriptional dysregulation between MSA and AD-related genes despite the clinical and neuropathological distinctions between the two diseases.

Multiple System Atrophy: Many Lessons from the Transcriptome

Multiple system atrophy (MSA) is a complex, multifactorial, debilitating neurodegenerative disease that is often misdiagnosed and misunderstood. MSA has two subclasses, MSA-P and MSA-C, defined by the dominance of parkinsonism or cerebellar dysfunction in the earlier stages of disease, coupled with dysautonomia. This distinction between subclasses becomes largely redundant as the disease progresses. Aggregation of α-synuclein is a clinical marker used to confirm MSA diagnoses, which can only be performed postmortem. Transcriptome profiling provides in-depth information about the diseased state and can contribute to further understanding of MSA, enabling easier and more rapid diagnosis as well as contributing to improving the quality of life of people with MSA. Currently, there is no method of diagnosing MSA with certainty, and there is no cure for this disease. This review provides an update on current advances in investigations of molecular pathology of MSA with particular focus on perturbation of individual gene expression and MSA transcriptome.

Autoimmune antibody decline in Parkinson's disease and Multiple System Atrophy; a step towards immunotherapeutic strategies

Background

Parkinson’s’ disease (PD) and Multiple System Atrophy (MSA) are progressive brain disorders characterized by intracellular accumulations of α-synuclein and nerve cell loss in specific brain areas. This loss causes problems with movement, balance and/or autonomic functions. Naturally occurring autoantibodies (NAbs) play potentially an important role in clearing or/and blocking circulating pathological proteins. Little is known about the functional properties of anti-α-synuclein NAbs in PD and MSA, and there have been opposing reports regarding their plasma concentrations in these disorders.

Methods

We have investigated the apparent affinity of anti-α-synuclein NAbs in plasma samples from 46 PD patients, 18 MSA patients and 41 controls using competitive enzyme-linked immunosorbent assay (ELISA) and Meso Scale Discovery (MSD) set-ups.

Results

We found that the occurrence of high affinity anti-α-synuclein NAbs in plasma from PD patients is reduced compared to healthy controls, and nearly absent in plasma from MSA patients. Also, levels of α-synuclein/NAbs immunocomplexes is substantially reduced in plasma from both patient groups. Further, cross binding of anti-α-synuclein NAbs with β- and γ-synuclein monomers suggest, the high affinity anti-α-synuclein plasma component, seen in healthy individuals, is directed mainly against C-terminal epitopes. Furthermore, we also observed reduced occurrence of high affinity anti-phosphorylated-α-synuclein NAbs in plasma from PD and MSA patients.

Conclusions

One interpretation implies that these patients may have impaired ability to clear and/or block the effects of pathological α-synuclein due to insufficient/absent concentration of NAbs and as such provides a rationale for testing immune-based therapeutic strategies directed against pathological α-synuclein. Following this interpretation, we can hypothesize that high affinity autoantibodies efficiently bind and clear potentially pathological species of α-synuclein in healthy brain, and that this mechanism is impaired or absent in PD and MSA patients.

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.

New insight into neurodegeneration: the role of proteomics

Recent advances within the field of proteomics, including both upstream and downstream protocols, have fuelled a transition from simple protein identification to functional analysis. A battery of proteomics approaches is now being employed for the analysis of protein expression levels, the monitoring of cellular activities and for gaining an increased understanding into biochemical pathways. Combined, these approaches are changing the way we study disease by allowing accurate and targeted, large scale protein analysis, which will provide invaluable insight into disease pathogenesis. Neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), prion disease, and other diseases that affect the neuromuscular system, are a leading cause of disability in the aging population. There are no effective intervention strategies for these disorders and diagnosis is challenging as it relies primarily on clinical symptomatic features, which often overlap at early stages of disease. There is, therefore, an urgent need to develop reliable biomarkers to improve early and specific diagnosis, to track disease progression, to measure molecular responses towards treatment regimes and ultimately devise new therapeutic strategies. To accomplish this, a better understanding of disease mechanisms is needed. In this review we summarize recent advances in the field of proteomics applicable to neurodegenerative disorders, and how these advances are fueling our understanding, diagnosis, and treatment of these complex disorders.

Deep brain stimulation response in pathologically confirmed cases of multiple system atrophy

Deep brain stimulation is a treatment for select cases of medication refractory movement disorders including Parkinson's disease. Deep brain stimulation has not been recommended for treatment in multiple system atrophy patients. However, the paucity of literature documenting the effects of deep brain stimulation in multiple system atrophy patients and the revelation of a levodopa responsive subtype of multiple system atrophy suggests further investigation is necessary. This study summarizes the positive and negative effects of deep brain stimulation treatment in two pathologically confirmed multiple system atrophy patients from the University of Florida Deep Brain Stimulation-Brain Tissue Network. Clinical diagnosis for the two patient cases did not match the neuropathological diagnosis. We noted that in both pathologically confirmed multiple system atrophy patients, death occurred as a result of myocardial infarction. Importantly, there was reported transient benefit in levodopa responsive features that indicate deep brain stimulation may be an option for select multiple system atrophy patients.

First report of a pathogenic mutation on exon 24 of the NOTCH3 gene in a CADASIL family

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a genetically transmitted small vessel disease clinically characterized by migraine, recurrent subcortical strokes, and cognitive and mood disorders. Pathogenic mutations are located on any of the exons of the NOTCH3 gene coding for epidermal-growth factor (EGF)-like repeats of the extracellular domain of the NOTCH3 receptor. Because the gene is large and the mutations cluster on some exons, many laboratories restrict the analysis to these exons. We report the first missense mutation involving exon 24 and causing CADASIL in a 64-year-old man. The patient was admitted to the hospital for a loss of consciousness accompanied by profuse sweating. On examination, some parkinsonian features were present. Over the last 4 years, he had developed postural instability and gait disturbances with repeated falls, behavioral disorders, and cognitive impairment. A diagnostic hypothesis of atypical parkinsonism had been advanced. The presence of multiple subcortical lacunar infarcts and leukoencephalopathy extended to the external capsule on cerebral MRI suggested the presence of CADASIL. The diagnosis was confirmed by finding a heterozygous mutation leading to a cysteine substitution on exon 24 of the NOTCH3 gene. One proband's brother, who had progressive gait disturbances, unilateral action tremor and bradykinesia, and an asymptomatic niece also resulted affected. This report underlines that when CADASIL is suspected the genetic analysis should be performed on all the NOTCH3 exons coding for EGF-like repeats including exon 24 and confirms that CADASIL may have heterogeneous phenotypes.

Multiple-system atrophy and medications: how to minimize the risk of falling

An 89-year-old female resident in the assisted living section of a continuing care retirement community complained of dizziness and lightheadedness at 10 am daily and was experiencing frequent falls. The facility staff requested a consultant pharmacist perform an extensive review of her medications and medical conditions. Following a chart review and interview with the resident, the consultant pharmacist found that her past medical history consists of coronary artery disease, atrial fibrillation, congestive heart failure, hypertension, dyslipidemia, osteoporosis, gastroesophageal reflux disease, glaucoma, mild dementia, overactive bladder, and Parkinson's disease (PD). The nursing staff monitored the resident's blood pressure during these episodes and determined that the resident was experiencing orthostatic hypotension (OH). During the review, the consultant pharmacist found a recent neurology note that concluded the resident may have multiple-system atrophy (MSA) and her therapy for PD may not be beneficial. As autonomic dysfunction is a common feature of MSA, it is important to minimize the use of medications that can cause or aggravate OH. Additionally, data suggest only a modest and nonsustained response to levodopa in patients with MSA. Therefore, the pharmacist recommended multiple medication changes as well as follow-up monitoring by the patient and assisted living community staff to minimize medication-related problems such as falls.

Morphometry MRI in the differential diagnosis of parkinsonian syndromes

This study evaluates the diagnostic value of morphometric magnetic resonance imaging (MRI) in the differential diagnosis among Parkinson's disease (PD), progressive supranuclear palsy (PSP) and multiple system atrophy (MSA). We studied 21 PD cases, 11 MSA-c, 8 MSA-p and 20 PSP cases. Midbrain area (Ams), pons area (Apn), middle cerebellar peduncle (MCP) and superior cerebellar peduncle (SCP) were measured using MRI. Comparisons were made between PD, MSA-p, MSA-c and PSP. Apn, MCP and SCP morphometry dimensions presented differences among groups. Ams below 105 mm(2) and SCP smaller than 3 mm were the most predictive measures of PSP (sensitivity 95.0 and 80.0%, respectively). For the group of MSA-c patients, Apn area below 315 mm(2) showed good specificity and positive predictive value (93.8% and 72.7%, respectively). In conclusion, dimensions and cut off values obtained from routine MRI can differentiate between PD, PSP and MSA-c with good sensitivity, specificity and accuracy.

Reversible sleep-related stridor during vagus nerve stimulation

A 23-year-old woman without history of antecedent vocal, respiratory, or sleep disorders received vagus nerve stimulation (VNS) therapy for refractory partial epilepsy and developed sleep-related stridor during the course of parameter titration. Reduction of VNS current during polysomnography completely eliminated stridor. We conclude that VNS may cause sleep-related stridor in rare cases, expanding the spectrum of known sleep-disordered breathing disorders associated with VNS therapy. Parameter adjustment during polysomnography may resolve nocturnal stridor caused by VNS.

Imaging in neurodegenerative disorders

This article discusses imaging findings of the cortical and subcortical neurodegenerative diseases. Spinocerebellar ataxia and neurodegenerative diseases secondary to vascular insults (multiinfarction dementia, Binswanger's disease, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, and amyloid angiopathy) are beyond the scope of this discussion.

How can neuroimaging help in the diagnosis of movement disorders?

The main role of computed axial tomography in the field of movement disorders was to exclude uncommon but potentially reversible structural abnormalities including tumors, chronic subdural hematoma, and communicating hydrocephalus presenting with parkinsonism. In the past 20 years magnetic resonance has had greater impact in facilitating accurate diagnosis but its clinical usefulness is less than in some other neurologic fields. Dopamine transporter SPECT imaging is helpful in distinguishing benign tremulous Parkinson disease from atypical tremor syndromes and other clinical scenarios where the demonstration of nigrostriatal dopamine denervation is helpful. We use eight case vignettes to illustrate how MR imaging findings can assist in the diagnosis of movement disorders and, in some cases, change the course of patient management.