Cognitive impairment in multiple system atrophy: a position statement by the Neuropsychology Task Force of the MDS Multiple System Atrophy (MODIMSA) study group

Multiple system atrophy

Multiple system atrophy (MSA) is a sporadic, adult-onset, relentlessly progressive neurodegenerative disorder, clinically characterized by various combinations of autonomic failure, parkinsonism and ataxia. The neuropathological hallmark of MSA are glial cytoplasmic inclusions consisting of misfolded α-synuclein. Selective atrophy and neuronal loss in striatonigral and olivopontocerebellar systems underlie the division into two main motor phenotypes of MSA-parkinsonian type and MSA-cerebellar type. Isolated autonomic failure and REM sleep behavior disorder are common premotor features of MSA. Beyond the core clinical symptoms, MSA manifests with a number of non-motor and motor features. Red flags highly specific for MSA may provide clues for a correct diagnosis, but in general the diagnostic accuracy of the second consensus criteria is suboptimal, particularly in early disease stages. In this chapter, the authors discuss the historical milestones, etiopathogenesis, neuropathological findings, clinical features, red flags, differential diagnosis, diagnostic criteria, imaging and other biomarkers, current treatment, unmet needs and future treatments for MSA.

Multiple System Atrophy: Recent Developments and Future Perspectives

Multiple system atrophy (MSA) is a rare and fatal neurodegenerative disorder characterized by a variable combination of parkinsonism, cerebellar impairment, and autonomic dysfunction. The pathologic hallmark is the accumulation of aggregated α-synuclein in oligodendrocytes, forming glial cytoplasmic inclusions, which qualifies MSA as a synucleinopathy together with Parkinson's disease and dementia with Lewy bodies. The underlying pathogenesis is still not well understood. Some symptomatic treatments are available, whereas neuroprotection remains an urgent unmet treatment need. In this review, we critically appraise significant developments of the past decade with emphasis on pathogenesis, diagnosis, prognosis, and treatment development. We further discuss unsolved questions and highlight some perspectives. © 2019 International Parkinson and Movement Disorder Society.

Orthostatic hypotension and REM sleep behaviour disorder: impact on clinical outcomes in α-synucleinopathies

OBJECTIVE

Review the effect of orthostatic hypotension (OH) and rapid-eye-movement sleep behavioural disorder (RBD) on survival, cognitive impairment and postural stability, and discuss pathogenic mechanisms involved in the association of these two common non-motor features with relevant clinical outcomes in α-synucleinopathies.

METHODS

We searched PubMed (January 2007-February 2019) for human studies of OH and RBD evaluating cognitive impairment, postural instability, and survival in Parkinson's disease (PD), dementia with Lewy bodies (DLB), multiple system atrophy (MSA) and pure autonomic failure (PAF). Included studies were analysed for design, key results and limitations as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

OH and RBD showed a positive association with cognitive impairment in PD and DLB, conflicting association in PAF, and no association in MSA. OH was correlated with incident falls and postural instability in PD and DLB but not in MSA. The association between RBD and postural instability was inconclusive; positive in five studies, negative in seven. OH, but not RBD, correlated with reduced survival in PD, DLB and MSA. The combination of OH and RBD was associated with cognitive impairment and more rapid progression of postural instability.

CONCLUSIONS

OH and RBD yielded individual and combined negative effects on disability in α-synucleinopathies, reflecting a 'malignant' phenotype of PD with early cognitive impairment and postural instability. Underlying mechanisms may include involvement of selected brainstem cholinergic and noradrenergic nuclei.

Falls in Synucleinopathies

Parkinson's disease (PD) and other synucleinopathies, namely dementia with Lewy bodies (DLB) and multiple system atrophy (MSA), are common degenerative neurological disorders that share synuclein pathology. Although certain cardinal features of parkinsonism, including bradykinesia and rigidity, respond well to levodopa, axial features, such as gait and balance impairment, are less reliably responsive to dopaminergic therapy and surgical interventions. Consequently, falls are common in PD and other synucleinopathies and are a major contributor toward injury and loss of independence. This underscores the need for appropriate fall risk assessment and implementation of preventative measures in all patients with parkinsonism. The aim of this review is therefore to explore modifiable and non-modifiable risk factors for falls in synucleinopathies. We next review and evaluate the evidence for pharmacological, nonpharmacological, and surgical approaches for fall prevention, and emphasize individualized and multifaceted approaches.

Locus coeruleus imaging as a biomarker for noradrenergic dysfunction in neurodegenerative diseases

Pathological alterations to the locus coeruleus, the major source of noradrenaline in the brain, are histologically evident in early stages of neurodegenerative diseases. Novel MRI approaches now provide an opportunity to quantify structural features of the locus coeruleus in vivo during disease progression. In combination with neuropathological biomarkers, in vivo locus coeruleus imaging could help to understand the contribution of locus coeruleus neurodegeneration to clinical and pathological manifestations in Alzheimer's disease, atypical neurodegenerative dementias and Parkinson's disease. Moreover, as the functional sensitivity of the noradrenergic system is likely to change with disease progression, in vivo measures of locus coeruleus integrity could provide new pathophysiological insights into cognitive and behavioural symptoms. Locus coeruleus imaging also holds the promise to stratify patients into clinical trials according to noradrenergic dysfunction. In this article, we present a consensus on how non-invasive in vivo assessment of locus coeruleus integrity can be used for clinical research in neurodegenerative diseases. We outline the next steps for in vivo, post-mortem and clinical studies that can lay the groundwork to evaluate the potential of locus coeruleus imaging as a biomarker for neurodegenerative diseases.

Frontal lobe function, behavioral changes and quality of life in patients with multiple system atrophy

BACKGROUND

Cognitive impairment is an important and common symptom in patients with multiple system atrophy (MSA).

OBJECTIVE

The objective of the study was to explore the potential relationships among frontal lobe function, behavioral changes and quality of life (QoL) in patients with MSA.

METHODS

A total of 203 MSA patients were enrolled and evaluated using the Frontal Assessment Battery (FAB), the Frontal Behavioral Inventory (FBI) and the Parkinson's disease Questionnaire-39 item version (PDQ-39). Seventy-eight age-, sex-, and education-matched healthy controls were recruited to complete the FAB.

RESULTS

Among MSA patients, those with frontal lobe dysfunction were older (P = 0.005), had older age of onset (P = 0.002), lower educational level (P <  0.001), higher scores in the PDQ-39 domains of mobility (P = 0.042), ADL (P = 0.020), cognition (P <  0.001) and communication compared to those with normal frontal lobe function. The most common frontal behavioral changes were logopenia followed by apathy and inflexibility. The severity of frontal behavioral changes was associated with MSA subtype (P = 0.015), disease severity (Unified Multiple System Atrophy Rating Scale-I (UMSARS-I), UMSARS-II, UMSARS-IV, and total UMSARS scores) (P <  0.001), orthostatic hypotension (P = 0.022), severity of depressive symptoms and total score on the PDQ-39 (P <  0.001). Binary logistic regression showed that the determinants of poor QoL in patients with MSA were disease severity (UMSARS-I and total UMSARS scores) (P <  0.05), depression (P = 0.013) and total FBI score (P = 0.003).

CONCLUSIONS

Frontal behavioral changes were potential determinants of poor QoL in MSA, in addition to the disease severity and depressive symptoms. Early discovery and management of frontal behavioral changes in addition to motor and depressive symptoms will help to improve the QoL of MSA patients.

Wide distribution of alpha-synuclein oligomers in multiple system atrophy brain detected by proximity ligation

Multiple system atrophy (MSA) is a fatal adult-onset neurodegenerative disease that is characterized by varying degrees of cerebellar dysfunction and Parkinsonism. The neuropathological hallmark of MSA is alpha-synuclein (AS)-positive glial cytoplasmic inclusions (GCIs). Although severe neuronal loss (NL) is also observed in MSA, neuronal inclusions (NIs) are rare compared to GCIs, such that the pathological mechanism of NL in MSA is unclear. GCIs and NIs are late-stage pathology features relative to AS oligomers and may not represent early pathological changes in MSA. To reveal the early pathology of MSA, it is necessary to examine the early aggregation of AS, i.e., AS oligomers. Here, we adopted a proximity ligation assay (PLA) to examine the distribution of AS oligomers in brain tissue samples from patients with MSA and other diseases. Surprisingly, MSA brains showed a widespread distribution and abundant accumulation of oligomeric AS in neurons as well as oligodendrocytes of the neocortex. In several regions, oligomeric AS signal intensity was higher in cases with MSA than in cases with Parkinson's disease. In contrast to previous studies, AS-PLA revealed abundant AS oligomer accumulation in Purkinje cells in MSA brains, identifying oligomeric AS accumulation as a possible cause of Purkinje cell loss. This wide distribution of AS oligomers in MSA brain neurons has not been described previously and indicates a pathological mechanism of NL in MSA.

Cardiac 123I-MIBG Scintigraphy in Neurodegenerative Parkinson Syndromes: Performance and Pitfalls in Clinical Practice

Purpose: Cardiac [¹²³I]metaiodobenzylguanidine scintigraphy (123I-MIBG), reflecting postganglionic cardiac autonomic denervation, is proposed for early detection of Parkinson's disease (PD; reduced tracer uptake) and separation from Multiple System Atrophy (MSA; preserved tracer uptake). However, several recent studies report on frequent unexpected 123I-MIBG results in PD and MSA. We sought to determine, whether 123I-MIBG is feasible to discriminate PD from MSA in unselected geriatric patients in clinical practice.

Materials and Methods: We screened consecutive patients, that underwent 123I-MIBG for diagnostic reasons. Delayed 123I-MIBG uptake (heart/mediastinum ratio; H/M ratio) was verified by clinical diagnosis of PD, MSA, and ET based on a two-stage clinical assessment: comprehensive baseline (including autonomic testing and additional neuroimaging) and confirmatory clinical follow-up.

Results: 28 patients with clinical diagnosis of PD (N = 11), MSA (N = 9), and Essential Tremor (ET, N = 8) were identified. In one third (9/28) nuclear medical diagnosis deviated from clinically suspected syndrome. Visual interpretation of 123I-MIBG identified two cases (MSA and ET) with indeed normal 123I-MIBG uptake. Detailed review of clinical phenotypes provided only in two cases (PD and ET) an adequate explanation (correction of initial diagnosis and confounding drug history) for unexpected 123I-MIBG. In conclusion, 123I-MIBG did not match initial clinical phenotype in 27% PD, 44% MSA, and 25% ET patients.

Conclusion: 123I-MIBG scintigraphy is a known specific and valuable technique in scientific approaches and well-defined and highly selected samples. However, predictability of 123I-MIBG based nuclear medical diagnosis for individual cases and thus, feasibility in routine clinical practice is limited. Our clinical series emphasize clinical verification of 123I-MIBG results on an individual basis in clinical routine.

Do multiple system atrophy and Parkinson's disease show distinct patterns of volumetric alterations across hippocampal subfields? An exploratory study

OBJECTIVES

To investigate the volumetric alterations of hippocampal subfields and identify which subfields contribute to mild cognitive impairment (MCI) in multiple system atrophy (MSA) and Parkinson's disease (PD).

METHODS

Thirty MSA-MCI, 26 PD-MCI, and 30 healthy controls were administered cognitive assessment, along with hippocampal segmentation using FreeSurfer 6.0 after a 3-T MRI scan. Regression analyses were performed between the volumes of hippocampal subfields and cognitive variables.

RESULTS

Compared with healthy controls, the volume of the hippocampal fissure was enlarged in PD-MCI patients, while left Cornu Ammonis (CA2-CA3), bilateral molecular layer, bilateral hippocampus-amygdala transition area, right subiculum, right CA1, right presubiculum, right parasubiculum, and bilateral whole hippocampus were reduced in the MSA-MCI group. Moreover, volumetric reductions of the bilateral hippocampal tail, bilateral CA1, bilateral presubiculum, bilateral molecular layer, left CA2-CA3, left hippocampus-amygdala transition area, right parasubiculum, and bilateral whole hippocampus were found in MSA-MCI relative to the PD-MCI group. The volumes of the left CA2-CA3 (B = - 11.34, p = 0.006) and left parasubiculum (B = 4.63, p = 0.01) were respectively correlated with language and abstraction functions. The volumes of the left fimbria (B = 6.99, p = 0.002) and left hippocampus-amygdala transition area (B = 2.28, p = 0.009) were correlated with visuospatial/executive function.

CONCLUSIONS

The MSA-MCI patients showed more widespread impairment of hippocampal subfields compared with the PD-MCI group, involving trisynaptic loop and amygdala-hippocampus interactions. The alteration of CA, hippocampus-amygdala transition area, and fimbria still requires further comparison between the two patient groups.

KEY POINTS

• The atrophy patterns of hippocampal subfields differed between MSA and PD patients. • MSA has widespread change in trisynaptic loop and amygdala-hippocampus interactions. • The atrophy patterns may help to understand the differences of cognitive impairment in MSA and PD.

Orthostatic hypotension and dementia incidence: links and implications

Orthostatic hypotension (OH) is a common condition, particularly in patients with α-synucleinopathies such as Parkinson's disease, and has a significant impact on activities of daily living and quality of life. Recent data suggest an association with cognitive impairment. Herein, we review the evidence that OH increases the odds of incident mild cognitive impairment and dementia. Potential mechanisms underlying the putative relationship are discussed, including cerebral hypoperfusion, supine hypertension, white matter hyperintensities, and neurodegeneration. Finally, we highlight the challenges with respect to treatment and the negative impact on the quality of life and long-term prognosis presented by the coexistence of OH and dementia. Large population-based studies have reported that OH is associated with about a 20% increased risk of dementia in the general population, while smaller cohort studies suggest an even greater effect in patients with α-synucleinopathies (3- to 7-fold higher than controls). Ultimately, OH exposure is difficult to quantify, predominantly limited to pressure regulation during a one-time orthostatic challenge, and the causative association with dementia may turn out to be bidirectional, especially in α-synucleinopathies. Early diagnosis and treatment of OH may improve long-term prognosis.

Brain morphological alteration and cognitive dysfunction in multiple system atrophy

Multiple system atrophy (MSA) is a progressive neurodegenerative disease in adults, manifesting various clinical symptoms including autonomic nerve dysfunction, Parkinson's syndrome, cerebellar ataxia, and pyramidal sign. The clinical diagnosis and classification of MSA are mainly dependent on motion and non-motion symptoms, such as autonomic nerve dysfunction. In addition, an increasing amount of clinical and pathological evidence has shown that about half of the MSA patients exhibit distinct types and levels of cognitive dysfunction. However, cognitive dysfunction has not been included in the current diagnosis criteria of MSA. In most cases, it was even used as an exclusion criterion of MSA. Based on the neuroimaging, neuropathology and neuropsychology, this review summarized the morphological changes of the brain in the patients with MSA, and discussed possible brain regions that could be associated with cognitive impairment. The article may provide a theoretical basis for incorporating cognitive dysfunction into the criteria of MSA diagnosis.

Neuropsychiatric disturbances in atypical parkinsonian disorders

Multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD) are the most common atypical parkinsonisms. These disorders are characterized by varying combinations of autonomic, cerebellar and pyramidal system, and cognitive dysfunctions. In this paper, we reviewed the evidence available on the presence and type of neuropsychiatric disturbances in MSA, PSP, and CBD. A MedLine, Excerpta Medica, PsycLit, PsycInfo, and Index Medicus search was performed to identify all articles published on this topic between 1965 and 2018. Neuropsychiatric disturbances including depression, anxiety, agitation, and behavioral abnormalities have been frequently described in these disorders, with depression as the most frequent disturbance. MSA patients show a higher frequency of depressive disorders when compared to healthy controls. An increased frequency of anxiety disorders has also been reported in some patients, and no studies have investigated apathy. PSP patients may have depression, apathy, disinhibition, and to a lesser extent, anxiety and agitation. In CBD, neuropsychiatric disorders are similar to those present in PSP. Hallucinations and delusions are rarely reported in these disorders. Neuropsychiatric symptoms in MSA, PSP, and CBD do not appear to be related to the severity of motor dysfunction and are one of the main factors that determine a low quality of life. The results suggest that neuropsychiatric disturbances should always be assessed in patients with atypical parkinsonisms.

Red flags phenotyping: A systematic review on clinical features in atypical parkinsonian disorders

To establish a clinical diagnosis of a parkinsonian disorder, physicians rely on their ability to identify relevant red flags, in addition to cardinal features, to support or refute their working diagnosis in an individual patient. The term 'red flag', was originally coined in 1989 to define the presence of non-cardinal features that may raise a suspicion of multiple system atrophy (MSA), or at least suggest alternative diagnosis to Parkinson's disease (PD). Since then, the term 'red flag', has been consistently used in the literature to denote the clinical history or signs that may signal to physicians the possibility of an atypical parkinsonian disorder (APD). While most red flags were originally based on expert opinion, many have gained acceptance and are now included in validated clinical diagnostic criteria of PD and APDs. The clinical appreciation of red flags, in conjunction with standard criteria, may result in a more accurate and earlier diagnosis compared to standard criteria alone. However, red flags can be clinical signs that are non-neurological, making the systematic assessment for them a real challenge in clinical practice. Here, we have conducted a systematic review to identify red flags and their clinical evidence in the differential diagnosis of common degenerative parkinsonism, including PD, MSA, progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), and dementia with Lewy body (DLB). Increasing awareness and appropriate use of red flags in clinical practice may benefit physicians in the diagnosis and management of their patients with parkinsonism.

Dementia

Dementia is any decline in cognition that is significant enough to interfere with independent, daily functioning. Dementia is best characterized as a syndrome rather than as one particular disease. The causes of dementia are myriad and include primary neurologic, neuropsychiatric, and medical conditions. It is common for multiple diseases to contribute to any one patient's dementia syndrome. Neurodegenerative dementias, like Alzheimer disease and dementia with Lewy bodies, are most common in the elderly, while traumatic brain injury and brain tumors are common causes in younger adults. While the recent decade has seen significant advancements in molecular neuroimaging, in understanding clinico-pathologic correlation, and in the development of novel biomarkers, clinicians still await disease-modifying therapies for neurodegenerative dementias. Until then, clinicians from varied disciplines and medical specialties are well poised to alleviate suffering, aggressively treat contributing conditions, employ medications to improve cognitive, neuropsychiatric, and motor symptoms, promote evidence-based brain-healthy behaviors, and improve overall quality of life for patients and families.

Diagnostic challenges in rapidly progressive dementia

INTRODUCTION

Rapidly progressive dementia is a syndrome caused by numerous disease entities. Accurate diagnosis is crucial as substantial proportion of these diseases is highly treatable. Others might implicate specific hygienic problems. Still, differential diagnosis remains challenging because of a huge overlap of clinical presentations. Areas covered: The paper reviews PubMed-listed research articles with a focus on diagnosis and treatment of diseases showing rapid cognitive decline such as inflammatory diseases, rapidly progressive neurodegenerative diseases, toxic-metabolic encephalopathies and prion diseases. The literature was interpreted in the light of experience in clinically differentiating rapid progressing dementia in the framework of Creutzfeldt-Jakob-Disease (CJD) surveillance activities. An overview of relevant differential diagnoses and diagnostic pitfalls as well as therapeutic protocols is presented. Expert commentary: Over the last years, more and more neurologic disorders causing cognitive symptoms, in particular various types of immune-mediated diseases have been discovered. To identify treatable conditions and to enhance knowledge of differential diagnosis and epidemiology, we suggest an extended diagnostic work up in cases with rapidly progressing dementia. Besides standard methods, this should include the search for neoplasia as well as atypical encephalitis. High-dose steroid therapy should be considered in certain clinical situations even when no evidence for inflammation is present.

Clinical and Imaging Features of Multiple System Atrophy: Challenges for an Early and Clinically Definitive Diagnosis

Multiple system atrophy (MSA) is an adult-onset, progressive neurodegenerative disorder. Patients with MSA show various phenotypes during the course of their illness, including parkinsonism, cerebellar ataxia, autonomic failure, and pyramidal signs. Patients with MSA sometimes present with isolated autonomic failure or motor symptoms/ signs. The median duration from onset to the concomitant appearance of motor and autonomic symptoms is approximately 2 years but can range up to 14 years. As the presence of both motor and autonomic symptoms is essential for the current diagnostic criteria, early diagnosis is difficult when patients present with isolated autonomic failure or motor symptoms/signs. In contrast, patients with MSA may show severe autonomic failure and die before the presentation of motor symptoms/signs, which are currently required for the diagnosis of MSA. Recent studies have also revealed that patients with MSA may show nonsupporting features of MSA such as dementia, hallucinations, and vertical gaze palsy. To establish early diagnostic criteria and clinically definitive categorization for the successful development of disease-modifying therapy or symptomatic interventions for MSA, research should focus on the isolated phase and atypical symptoms to develop specific clinical, imaging, and fluid biomarkers that satisfy the requirements for objectivity, for semi- or quantitative measurements, and for uncomplicated, worldwide availability. Several novel techniques, such as automated compartmentalization of the brain into multiple parcels for the quantification of gray and white matter volumes on an individual basis and the visualization of α-synuclein and other candidate serum and cerebrospinal fluid biomarkers, may be promising for the early and clinically definitive diagnosis of MSA.

Corpus callosal involvement is correlated with cognitive impairment in multiple system atrophy

OBJECTIVE

We examined the anatomical involvement related to cognitive impairment in patients with multiple system atrophy (MSA).

METHODS

We examined 30 patients with probable MSA and 15 healthy controls. All MSA patients were assessed by the Unified MSA-Rating scale and Addenbrooke's Cognitive Examination-Revised (ACE-R). We classified 15 MSA patients with ACE-R scores > 88 as having normal cognition (MSA-NC) and 15 with scores ≤ 88 as having cognitive impairment (MSA-CI). All subjects underwent 3 T MRI scanning and were investigated using voxel-based morphometry and diffusion tensor imaging.

RESULTS

Both the MSA-NC and MSA-CI patients exhibited cerebellar but not cerebral atrophy in voxel-based morphometry compared to controls. In contrast, tract-based spatial statistics revealed widespread and significantly decreased fractional anisotropy (FA) values, as well as increased mean diffusivity, radial diffusivity, and axial diffusivity in both the cerebrum and cerebellum in MSA-CI patients compared to controls. MSA-NC patients also exhibited similar involvement of the cerebellum but less extensive involvement of the cerebrum compared with the MSA-CI patients. In particular, FA values in MSA-CI patients were significantly decreased in the anterior part of the left corpus callosum compared with those in MSA-NC patients. The mean FA values in the left anterior part of the corpus callosum were significantly correlated with total ACE-R scores and subscores (memory, fluency, and language) in MSA patients.

CONCLUSIONS

Decreased FA values in the anterior corpus callosum showed a significant correlation with cognitive impairment in MSA.

Mitochondrial dysfunction and altered ribostasis in hippocampal neurons with cytoplasmic inclusions of multiple system atrophy

Multiple system atrophy (MSA) is a sporadic adult-onset neurodegenerative disease. It has recently been shown that patients with MSA accompanied by cognitive decline display numerous neuronal cytoplasmic inclusions (NCIs) in the limbic neurons. We examined potential mechanisms underlying the formation of these NCIs by determining of mitochondrial function and statuses of RNA processing by analyzing 12 pathologically confirmed cases of MSA. Among them, four had cognitive impairment Semiquantitative evaluation using immunohistochemistry analyses revealed a significantly greater NCI burden in the hippocampal cornu ammonis 1 (CA1) subfield, subiculum, and amygdala in the cases with cognitive impairments compared with those without cognitive impairment. Immunofluorescent staining revealed that limbic neurons with NCIs often accelerated production of reactive oxygen species (ROS) and degraded mitochondrial quality control. Immunofluorescent staining also revealed that neurons with these NCIs translocated heterogeneous nuclear ribonucleoprotein A1 (HNRNPA1) from the nucleus and aggregated abnormally at the perinuclear rim. Since the NCIs in the hippocampal neurons of MSA with cognitive impairments were more numerous, the neuronal mitochondrial dysfunction and altered ribostasis observed in NCI formation may be involved in the hippocampal degeneration of MSA.

TDP-43 pathology in multiple system atrophy: colocalization of TDP-43 and α-synuclein in glial cytoplasmic inclusions

AIMS

This study aimed to assess clinicopathologic features of transactive response DNA-binding protein of 43 kDa (TDP-43) pathology and its risk factors in multiple system atrophy (MSA).

METHODS

Paraffin-embedded sections of the amygdala and basal forebrain from 186 autopsy-confirmed MSA cases were screened with immunohistochemistry for phospho-TDP-43. In cases having TDP-43 pathology, additional brain regions were assessed. Immunohistochemical and immunofluorescence double-staining and immunogold electron microscopy (IEM) were performed to evaluate colocalization of TDP-43 and α-synuclein. Genetic risk factors for TDP-43 pathology were also analysed.

RESULTS

Immunohistochemistry showed various morphologies of TDP-43 pathology in 13 cases (7%), such as subpial astrocytic inclusions, neuronal inclusions, dystrophic neurites, perivascular inclusions and glial cytoplasmic inclusions (GCIs). Multivariable logistic regression models revealed that only advanced age, but not concurrent Alzheimer's disease, argyrophilic grain disease or hippocampal sclerosis, was an independent risk factor for TDP-43 pathology in MSA (OR: 1.11, 95% CI: 1.04-1.19, P = 0.002). TDP-43 pathology was restricted to the amygdala in eight cases and extended to the hippocampus in two cases. The remaining three cases had widespread TDP-43 pathology. Immunohistochemical and immunofluorescence double-staining and IEM revealed colocalization of α-synuclein and TDP-43 in GCIs with granule-coated filaments. Pilot genetic studies failed to show associations between risk variants of TMEM106B or GRN and TDP-43 pathology.

CONCLUSIONS

TDP-43 pathology is rare in MSA and occurs mainly in the medial temporal lobe. Advanced age is a risk factor for TDP-43 pathology in MSA. Colocalization of TDP-43 and α-synuclein in GCIs suggests possible direct interaction between the two molecules.

Diagnosis of multiple system atrophy

Multiple system atrophy (MSA) may be difficult to distinguish clinically from other disorders, particularly in the early stages of the disease. An autonomic-only presentation can be indistinguishable from pure autonomic failure. Patients presenting with parkinsonism may be misdiagnosed as having Parkinson disease. Patients presenting with the cerebellar phenotype of MSA can mimic other adult-onset ataxias due to alcohol, chemotherapeutic agents, lead, lithium, and toluene, or vitamin E deficiency, as well as paraneoplastic, autoimmune, or genetic ataxias. A careful medical history and meticulous neurological examination remain the cornerstone for the accurate diagnosis of MSA. Ancillary investigations are helpful to support the diagnosis, rule out potential mimics, and define therapeutic strategies. This review summarizes diagnostic investigations useful in the differential diagnosis of patients with suspected MSA. Currently used techniques include structural and functional brain imaging, cardiac sympathetic imaging, cardiovascular autonomic testing, olfactory testing, sleep study, urological evaluation, and dysphagia and cognitive assessments. Despite advances in the diagnostic tools for MSA in recent years and the availability of consensus criteria for clinical diagnosis, the diagnostic accuracy of MSA remains sub-optimal. As other diagnostic tools emerge, including skin biopsy, retinal biomarkers, blood and cerebrospinal fluid biomarkers, and advanced genetic testing, a more accurate and earlier recognition of MSA should be possible, even in the prodromal stages. This has important implications as misdiagnosis can result in inappropriate treatment, patient and family distress, and erroneous eligibility for clinical trials of disease-modifying drugs.

Clinical Neurology and Epidemiology of the Major Neurodegenerative Diseases

Neurodegenerative diseases are a common cause of morbidity and cognitive impairment in older adults. Most clinicians who care for the elderly are not trained to diagnose these conditions, perhaps other than typical Alzheimer's disease (AD). Each of these disorders has varied epidemiology, clinical symptomatology, laboratory and neuroimaging features, neuropathology, and management. Thus, it is important that clinicians be able to differentiate and diagnose these conditions accurately. This review summarizes and highlights clinical aspects of several of the most commonly encountered neurodegenerative diseases, including AD, frontotemporal dementia (FTD) and its variants, progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), Parkinson's disease (PD), dementia with Lewy bodies (DLB), multiple system atrophy (MSA), and Huntington's disease (HD). For each condition, we provide a brief overview of the epidemiology, defining clinical symptoms and diagnostic criteria, relevant imaging and laboratory features, genetics, pathology, treatments, and differential diagnosis.

Recent advances in neuropathology, biomarkers and therapeutic approach of multiple system atrophy

Multiple system atrophy (MSA) is a progressive neurodegenerative disorder characterised by a variable combination of autonomic failure, levodopa-unresponsive parkinsonism, cerebellar ataxia and pyramidal symptoms. The pathological hallmark is the oligodendrocytic glial cytoplasmic inclusion (GCI) consisting of α-synuclein; therefore, MSA is included in the category of α-synucleinopathies. MSA has been divided into two clinicopathological subtypes: MSA with predominant parkinsonism and MSA with predominant cerebellar ataxia, which generally correlate with striatonigral degeneration and olivopontocerebellar atrophy, respectively. It is increasingly recognised, however, that clinical and pathological features of MSA are broader than previously considered.In this review, we aim to describe recent advances in neuropathology of MSA from a review of the literature and from information derived from review of nearly 200 definite MSA cases in the Mayo Clinic Brain Bank. In light of these new neuropathological findings, GCIs and neuronal cytoplasmic inclusions play an important role in clinicopathological correlates of MSA. We also focus on clinical diagnostic accuracy and differential diagnosis of MSA as well as candidate biomarkers. We also review some controversial topics in MSA. Cognitive impairment, which has been a non-supporting feature of MSA, is considered from both clinical and pathological perspectives. The cellular origin of α-synuclein in GCI and a 'prion hypothesis' are discussed. Finally, completed and ongoing clinical trials targeting disease modification, including immunotherapy, are summarised.

Multiple System Atrophy: An Oligodendroglioneural Synucleinopathy1

Multiple system atrophy (MSA) is an orphan, fatal, adult-onset neurodegenerative disorder of uncertain etiology that is clinically characterized by various combinations of parkinsonism, cerebellar, autonomic, and motor dysfunction. MSA is an α-synucleinopathy with specific glioneuronal degeneration involving striatonigral, olivopontocerebellar, and autonomic nervous systems but also other parts of the central and peripheral nervous systems. The major clinical variants correlate with the morphologic phenotypes of striatonigral degeneration (MSA-P) and olivopontocerebellar atrophy (MSA-C). While our knowledge of the molecular pathogenesis of this devastating disease is still incomplete, updated consensus criteria and combined fluid and imaging biomarkers have increased its diagnostic accuracy. The neuropathologic hallmark of this unique proteinopathy is the deposition of aberrant α-synuclein in both glia (mainly oligodendroglia) and neurons forming glial and neuronal cytoplasmic inclusions that cause cell dysfunction and demise. In addition, there is widespread demyelination, the pathogenesis of which is not fully understood. The pathogenesis of MSA is characterized by propagation of misfolded α-synuclein from neurons to oligodendroglia and cell-to-cell spreading in a "prion-like" manner, oxidative stress, proteasomal and mitochondrial dysfunction, dysregulation of myelin lipids, decreased neurotrophic factors, neuroinflammation, and energy failure. The combination of these mechanisms finally results in a system-specific pattern of neurodegeneration and a multisystem involvement that are specific for MSA. Despite several pharmacological approaches in MSA models, addressing these pathogenic mechanisms, no effective neuroprotective nor disease-modifying therapeutic strategies are currently available. Multidisciplinary research to elucidate the genetic and molecular background of the deleterious cycle of noxious processes, to develop reliable biomarkers and targets for effective treatment of this hitherto incurable disorder is urgently needed.

Association Between Poor Cognitive Functioning and Risk of Incident Parkinsonism: The Rotterdam Study

Importance

Cognitive dysfunction is a common feature among patients with parkinsonism, including Parkinson disease (PD). However, there is a scarcity of data on cognitive functioning before parkinsonism diagnosis, a stage at which patients may still respond to putative disease-modifying interventions.

Objective

To assess whether poor cognitive functioning is associated with an increased risk of parkinsonism.

Design, Setting, and Participants

Between January 8, 2002, and December 14, 2008, baseline cognitive function was assessed in 7386 participants of the Rotterdam Study who were free of parkinsonism and dementia. Four tests were administered (Stroop color word test, letter-digit substitution, verbal fluency, and word learning) and a global cognition score was derived from principal component analysis. Subsequently, participants were followed up until January 1, 2015, for the onset of parkinsonism through serial in-person examinations and complete access to medical records. Parkinsonism was defined as the (1) presence of hypokinesia or bradykinesia plus at least 1 other cardinal sign and/or (2) clinical diagnosis by a neurologist or geriatrician. Patients with dementia diagnosis before parkinsonism diagnosis were considered to have probable PD.

Main Outcomes and Measures

Hazard ratios (HRs) for incident parkinsonism per SD decrease in global cognition, adjusted for age, sex, and study subcohort.

Results

A total of 7386 patients were included in the analysis; of these, 4236 (57.4%) were women and mean (SD) age was 65.3 (10.2) years. During follow-up (median, 8.3 years; range, 0-15 years), 79 (1.1%) individuals received a diagnosis of incident parkinsonism; of these, 57 (72.2%) received a diagnosis of probable PD. Among patients with incident parkinsonism, 24 (30.4%) also developed dementia (10 before and 14 after parkinsonism onset). Poor global cognition at baseline was associated with a higher hazard of incident parkinsonism (hazard ratio [HR], 1.79; 95% CI, 1.37-2.33). The association remained robust beyond the first 8 years (HR, 1.59; 95% CI, 1.01-2.59) and after removing individuals with dementia onset before parkinsonism (HR, 1.72; 95% CI, 1.28-2.27). Poor global cognition at baseline was also associated with incident probable PD (HR, 1.52; 95% CI, 1.11-2.08). Letter-digit substitution (HR, 1.59; 95% CI, 1.22-2.04), verbal fluency (HR, 1.61; 95% CI, 1.23-2.08), and inverted interference task Stroop color word test (HR, 1.56; 95% CI, 1.25-1.96) scores were each associated with incident parkinsonism, whereas the association with word learning delayed-task scores was weaker (HR, 1.18; 95% CI, 0.92-1.52).

Conclusions and Relevance

Poor cognitive functioning is associated with an increased risk of incident parkinsonism, including probable PD. Cognition indicates the probability of parkinsonism over long intervals and extends beyond patients with onset of parkinsonism after dementia. The findings suggest that cognitive dysfunction can be considered a sign of prodromal PD.

Comparing abnormalities of amplitude of low-frequency fluctuations in multiple system atrophy and idiopathic Parkinson's disease measured with resting-state fMRI

Multiple system atrophy (MSA) and Idiopathic Parkinson's disease (IPD) show overlapping clinical manifestations with different treatment and prognosis. However, the shared and distinct underlying neural substrates are not yet understood, which needs to be explored between MSA and IPD. Resting-state functional magnetic resonance imaging data were collected from 29 MSA patients, 17 IPD patients and 25 healthy controls (HC) and the Amplitude of Low-Frequency Fluctuations (ALFF) was compared. Lower ALFF in bilateral basal ganglion, bilateral ventrolateral prefrontal cortex and right amygdala, as well as higher ALFF in parieto-temporo-occipital cortex and right cerebellum was shared between both patient groups to compare with HC. In contrast to IPD, decreased or increased ALFF in different regions of visual associative cortices and decreased ALFF in right cerebellum were found in MSA group. Our findings suggested shared and distinct spontaneous brain activity abnormalities in striato-thalamo-cortical (STC) loop, default mood network, visual associative cortices and cerebellum were present in MSA and IPD, which may help to explain similar clinical symptoms in both disorders but a more severe illness prognosis in MSA. Further research is needed to better describe the functional role of the cerebellum and visual associative cortices in early stages of MSA and IPD.

A Card-type Odor Identification Test for Japanese Patients with Parkinson's Disease and Related Disorders

Objective The characteristics of olfactory impairment in Parkinson's disease (PD), multiple system atrophy (MSA) and progressive supranuclear palsy (PSP) have not been determined in detail. We assessed the olfactory function among PD, MSA and PSP patients. Methods A card-type odor identification test, Open Essence (OE, Wako, Japan), which consists of 12 different odorants familiar to Japanese subjects, was administered to 98 PD patients, 32 MSA patients, 17 PSP patients and 96 control subjects ≥50 years of age. Results The PD patients had significantly lower OE scores than the other groups. The OE scores of the MSA and PSP patients fell between those of the PD patients and the control subjects. A cut-off OE score of 6 was beneficial for differentiating PD patients from controls with 84.7% sensitivity and 85.4% specificity. A cut-off OE score of 4 had 60.2% sensitivity and 77.6% specificity for differentiating PD patients from MSA and PSP patients. The correct answer rates for the curry, Japanese orange and perfume odorants in the PD patients were lower than those in the MSA and PSP patients and controls. The PD patients also had the highest ratio of "not detected" choices across the 12 odors. Conclusion Marked olfactory impairment was a feature of the patients with PD, while mild olfactory impairment was observed in those with MSA or PSP. The answer patterns and the specific odorants may also be useful in differentiating PD from related disorders.

Divergent Thinking in Parkinsonism: A Case-Control Study

BACKGROUND

Creativity is a multidimensional phenomenon and an important component of human capacities. This ability is characterized by the involvement of several cognitive functions particularly linked to the prefrontal cortex. We compared divergent thinking, a measure of creativity, in patients affected by progressive supranuclear palsy (PSP), other parkinsonian syndromes, and healthy controls (HCs).

METHODS

Creativity features were evaluated using the Abbreviated Torrance Test for Adults (ATTA). Consecutive PSP outpatients were screened for inclusion. Then, patients with multiple system atrophy (MSA) and Parkinson's disease (PD) and a group of HC were studied. All groups have preserved cognitive functions and were matched for gender, education, disease duration, and age at onset with exception of PD patients who were matched by disease severity rather than disease duration.

RESULTS

PSP patients were characterized by lower values in total ATTA and all subscales than HC and both MSA and PD patients. No differences were found comparing HC versus both MSA and PD patients. PSP patients were characterized by more impaired frontal functioning [assessed by means of Frontal Assessment Battery (FAB)] than HC and both PD and MSA patients.

CONCLUSION

In the present study, ATTA was significantly lower in PSP patients than in the other study groups. The worst performance in ATTA-total score and the lower score in FAB in PSP patients support the role of frontal function in creative processes.

The Diagnosis and Natural History of Multiple System Atrophy, Cerebellar Type

The objective of this study was to identify key features differentiating multiple system atrophy cerebellar type (MSA-C) from idiopathic late-onset cerebellar ataxia (ILOCA). We reviewed records of patients seen in the Massachusetts General Hospital Ataxia Unit between 1992 and 2013 with consensus criteria diagnoses of MSA-C or ILOCA. Twelve patients had definite MSA-C, 53 had possible/probable MSA-C, and 12 had ILOCA. Autonomic features, specifically urinary urgency, frequency, and incontinence with erectile dysfunction in males, differentiated MSA-C from ILOCA throughout the disease course (p = 0.005). Orthostatic hypotension developed later and differentiated MSA-C from ILOCA (p < 0.01). REM sleep behavior disorder (RBD) occurred early in possible/probable MSA-C (p < 0.01). Late MSA-C included pathologic laughing and crying (PLC, p < 0.01), bradykinesia (p = 0.01), and corticospinal findings (p = 0.01). MRI distinguished MSA-C from ILOCA by atrophy of the brainstem (p < 0.01) and middle cerebellar peduncles (MCP, p = 0.02). MSA-C progressed faster than ILOCA: by 6 years, MSA-C walker dependency was 100 % and ILOCA 33 %. MSA-C survival was 8.4 ± 2.5 years. Mean length of ILOCA illness to date is 15.9 ± 6.4 years. A sporadic onset, insidiously developing cerebellar syndrome in midlife, with autonomic features of otherwise unexplained bladder dysfunction with or without erectile dysfunction in males, and atrophy of the cerebellum, brainstem, and MCP points strongly to MSA-C. RBD and postural hypotension confirm the diagnosis. Extrapyramidal findings, corticospinal tract signs, and PLC are helpful but not necessary for diagnosis. Clarity in early MSA-C diagnosis can prevent unnecessary investigations and facilitate therapeutic trials.

Multiple System Atrophy - State of the Art

Multiple system atrophy (MSA) is a rare and fatal neurodegenerative disorder that is characterized by a variable combination of parkinsonism, cerebellar impairment, and autonomic dysfunction. Some symptomatic treatments are available while neuroprotection or disease-modification remain unmet treatment needs. The pathologic hallmark is the accumulation of aggregated alpha-synuclein (α-syn) in oligodendrocytes forming glial cytoplasmic inclusions, which qualifies MSA as synucleinopathy together with Parkinson's disease and dementia with Lewy bodies. Despite progress in our understanding of the pathogenesis of MSA, the origin of α-syn aggregates in oligodendrocytes is still a matter of an ongoing debate. We critically review here studies published in the field over the past 5 years dealing with pathogenesis, genetics, clinical signs, biomarker for improving diagnostic accuracy, and treatment development.

Pain processing in atypical Parkinsonisms and Parkinson disease: A comparative neurophysiological study

OBJECTIVE

Pain is a frequent non-motor feature in Parkinsonism but mechanistic data on the alteration of pain processing are insufficient to understand the possible causes and to define specifically-targeted treatments.

METHODS

we investigated spinal nociception through the neurophysiological measure of the threshold (TR) of nociceptive withdrawal reflex (NWR) and its temporal summation threshold (TST) comparatively in 12 Progressive Supranuclear Palsy (PSP) subjects, 11 Multiple System Atrophy (MSA) patients, 15 Parkinson's disease (PD) subjects and 24 healthy controls (HC). We also investigated the modulatory effect of L-Dopa in these three parkinsonian groups.

RESULTS

We found a significant reduction in the TR of NWR and in the TST of NWR in PSP, MSA and PD patients compared with HC. L-Dopa induced an increase in the TR of NWR in the PSP group while TST of NWR increased in both PSP and PD.

CONCLUSIONS

Our neurophysiological findings identify a facilitation of nociceptive processing in PSP that is broadly similar to that observed in MSA and PD. Specific peculiarities have emerged for PSP.

SIGNIFICANCE

Our data advance the knowledge of the neurophysiology of nociception in the advanced phases of parkinsonian syndromes and on the role of dopaminergic pathways in the control on pain processing.

Synucleinopathies: common features and hippocampal manifestations

Parkinson's disease (PD), dementia with Lewy Bodies (DLB), and multiple system atrophy (MSA) are three major synucleinopathies characterized by α-synuclein-containing inclusions in the brains of patients. Because the cell types and brain structures that are affected vary markedly between the disorders, the patients have different clinical manifestations in addition to some overlapping symptoms, which are the basis for differential diagnosis. Cognitive impairment and depression associated with hippocampal dysfunction are frequently observed in these disorders. While various α-synuclein-containing inclusions are found in the hippocampal formation, increasing evidence supports that small α-synuclein aggregates or oligomers may be the real culprit, causing deficits in neurotransmission and neurogenesis in the hippocampus and related brain regions, which constitute the major mechanism for the hippocampal dysfunctions and associated neuropsychiatric manifestations in synucleinopathies.

Multiple system atrophy: insights into a rare and debilitating movement disorder

Multiple system atrophy (MSA) is a devastating and fatal neurodegenerative disorder. The clinical presentation of this disease is highly variable, with parkinsonism, cerebellar ataxia and autonomic failure being the most common - and often debilitating - symptoms. These symptoms progress rapidly, and patients die from MSA-related complications after 9 years of symptom duration on average. Unfortunately, the course of the disease cannot be improved by drug or surgical treatment. In addition, symptomatic treatment options are currently limited, and therapeutic benefits are often only transient. Thus, further interventional studies of candidate disease-modifying and symptomatic therapies are essential to improve patient care. In the past 15 years, the understanding of MSA-specific requirements in trial methodology has improved, resulting in a substantial increase in high-quality interventional studies. In this Review, we discuss MSA risk factors, clinical presentation and neuropathology, and we provide a hypothesis on key pathophysiological events, a summary of recent randomized controlled trials, and an overview of ongoing international collaborations.

Modulation of Cerebellar-Cortical Connections in Multiple System Atrophy Type C by Cerebellar Repetitive Transcranial Magnetic Stimulation

OBJECTIVE

This study aims at modulating the altered cerebellar-cortical interactions in patients with multiple system atrophy-cerebellar subtype (MSA-C) by using cerebellar repetitive transcranial magnetic stimulation (rTMS). We hypothesized that cerebellar modulation by low-frequency rTMS can resolve the abnormal cortical excitability in multiple system atrophy cerebellar subtype.

MATERIALS AND METHODS

We studied detailed effects of rTMS of the cerebellum on reaction time (RT) and short-latency afferent inhibition (SAI) response in MSA-C group, Alzheimer Disease (AD) group, and a control group of healthy individuals. The RT and SAI responses were measured before and after 1 Hz cerebellar rTMS in all groups. The study was conducted in the neurophysiology laboratory in Hacettepe University Hospital.

RESULTS

Our results indicated that motor cortex disinhibition was predominant in patients with AD and MSA-C. In AD and control groups, there were no changes in SAI after rTMS. However, after application of rTMS over the cerebellum in MSA-C patients, the pathological disinhibition and RT results showed an improvement compared to their previous results.

CONCLUSION

Our study highlights that cerebellar rTMS impairs abnormal cerebellar-cortical inhibitory connections in case of MSA-C.