Laboratory-Supported Multiple System Atrophy beyond Autonomic Function Testing and Imaging: A Systematic Review by the MoDiMSA Study Group

Definition and diagnosis of Parkinson's disease: guideline "Parkinson's disease" of the German Society of Neurology

BACKGROUND

Accurate definition and operational criteria for diagnosing Parkinson's disease (PD) are crucial for evidence-based, patient-centered care.

OBJECTIVE

To offer evidence-based recommendations for defining and diagnosing PD, incorporating contemporary clinical, imaging, biomarker, and genetic insights.

METHODS

The guideline development began with the steering committee establishing key PICO (patient, intervention, comparison, outcome) questions, which were refined by the coauthors. Systematic literature searches identified relevant studies, reviews, and meta-analyses. Recommendations were drafted, evaluated, optimized, and voted upon by the German Parkinson's Guideline Group.

RESULTS

Parkinson's disease (PD) is now understood to encompass a broader spectrum of etiologies than previously recognized. Advances in molecular pathogenesis, neuroimaging, and early clinical phenotypes suggest that PD is not a uniform disease entity and is often not idiopathic. This necessitates an updated framework for PD definition and diagnosis. The German Society for Neurology now endorses a broader concept of PD, incorporating both idiopathic and hereditary forms, as opposed to the previously narrower concept of "idiopathic Parkinson syndrome." The revised guidelines recommend using the 2015 Movement Disorders Society diagnostic criteria, emphasize the importance of long-term clinical follow-up for improved diagnostic accuracy, and highlight the significance of non-motor symptoms in clinical diagnosis. Specific recommendations are provided for the use of imaging and fluid biomarkers and genetic testing to support the clinical diagnosis.

CONCLUSION

The updated guidelines from the German Society for Neurology enhance diagnostic accuracy for PD, promoting optimized clinical care.

Multiple system atrophy: Diagnostic challenges and a proposed diagnostic algorithm

Multiple system atrophy (MSA) is a heterogenous condition, presenting with core clinical features of autonomic dysfunction, parkinsonism, and/or cerebellar ataxia. The presence of alpha-synuclein glial cytoplasmic inclusion is the hallmark of MSA. It shares a common pathological origin with Parkinson's disease (PD) and Lewy body dementia (DLB) and they are collectively grouped as "synucleinopathies." The pathological synuclein protein is now well- recognized in skin biopsies of these patients. Besides the pathological findings, radiological investigation is a useful diagnostic tool. Brain MRI helps rule out other etiologies, and findings like the "Hot-cross bun" sign, "putaminal atrophy," and "infratentorial findings" can assist with the diagnosis of MSA. Cardiac MIBG scan, autonomic testing, urodynamic studies can help differentiate MSA from other conditions. Although diagnostic tools are available for MSA diagnosis, clarity is needed on when to use these tests. We suggest a diagnostic algorithm to navigate the use of these tests. However, this algorithm is not intended to replace the use of current MDS diagnostic criteria of MSA.

A Review on the Clinical Diagnosis of Multiple System Atrophy

Multiple system atrophy (MSA) is a rare, adult-onset, progressive neurodegenerative disorder with major diagnostic challenges. Aiming for a better diagnostic accuracy particularly at early disease stages, novel Movement Disorder Society criteria for the diagnosis of MSA (MDS MSA criteria) have been recently developed. They introduce a neuropathologically established MSA category and three levels of clinical diagnostic certainty including clinically established MSA, clinically probable MSA, and the research category of possible prodromal MSA. The diagnosis of clinically established and clinically probable MSA is based on the presence of cardiovascular or urological autonomic failure, parkinsonism (poorly L-Dopa-responsive for the diagnosis of clinically established MSA), and cerebellar syndrome. These core clinical features need to be associated with supportive motor and non-motor features (MSA red flags) and absence of any exclusion criteria. Characteristic brain MRI markers are required for a diagnosis of clinically established MSA. A research category of possible prodromal MSA is devised to capture patients manifesting with autonomic failure or REM sleep behavior disorder and only mild motor signs at the earliest disease stage. There is a number of promising laboratory markers for MSA that may help increase the overall clinical diagnostic accuracy. In this review, we will discuss the core and supportive clinical features for a diagnosis of MSA in light of the new MDS MSA criteria, which laboratory tools may assist in the clinical diagnosis and which major differential diagnostic challenges should be borne in mind.

Multiple system atrophy

This is a practical guide to diagnosing and managing multiple system atrophy (MSA). We explain the newly published Movement Disorders Society Consensus Diagnostic Criteria, which include new 'Clinically Established MSA' and 'Possible Prodromal MSA' categories, hopefully reducing time to diagnosis. We then highlight the key clinical features of MSA to aid diagnosis. We include a list of MSA mimics with suggested methods of differentiation from MSA. Lastly, we discuss practical symptom management in people living with MSA, including balancing side effects, with the ultimate aim of improving quality of life.

A case of Lewy body disease and anaplastic astrocytoma presenting with atypical parkinsonism

We report on a patient with atypical parkinsonism due to coexistent Lewy body disease (LBD) and diffuse anaplastic astrocytoma. The patient presented with a mixed cerebellar and parkinsonian syndrome, incomplete levodopa response, and autonomic failure. The clinical diagnosis was multiple system atrophy (MSA). Supportive features of MSA according to the consensus diagnostic criteria included postural instability and early falls, early dysphagia, pyramidal signs, and orofacial dystonia. Multiple exclusion criteria for a diagnosis of idiopathic Parkinson's disease (iPD) were present. Neuropathological examination of the left hemisphere and the whole midbrain and brainstem revealed LBD, neocortical-type consistent with iPD, hippocampal sclerosis, and widespread neoplastic infiltration by an anaplastic astrocytoma without evidence of a space occupying lesion. There were no pathological features of MSA. The classification of atypical parkinsonism was difficult in this patient. The clinical features and disease course were confounded by the coexistent tumor, leading to atypical presentation and a diagnosis of MSA. We suggest that the initial features were due to Lewy body pathology, while progression and ataxia, pyramidal signs, and falls were accelerated by the occurrence of the astrocytoma. Our case reflects the challenges of an accurate diagnosis of atypical parkinsonism, the potential for confounding co-pathology and the need for autopsy examination to reach a definitive diagnosis.

Multiple system atrophy

Multiple system atrophy (MSA) is a rare neurodegenerative disease that is characterized by neuronal loss and gliosis in multiple areas of the central nervous system including striatonigral, olivopontocerebellar and central autonomic structures. Oligodendroglial cytoplasmic inclusions containing misfolded and aggregated α-synuclein are the histopathological hallmark of MSA. A firm clinical diagnosis requires the presence of autonomic dysfunction in combination with parkinsonism that responds poorly to levodopa and/or cerebellar ataxia. Clinical diagnostic accuracy is suboptimal in early disease because of phenotypic overlaps with Parkinson disease or other types of degenerative parkinsonism as well as with other cerebellar disorders. The symptomatic management of MSA requires a complex multimodal approach to compensate for autonomic failure, alleviate parkinsonism and cerebellar ataxia and associated disabilities. None of the available treatments significantly slows the aggressive course of MSA. Despite several failed trials in the past, a robust pipeline of putative disease-modifying agents, along with progress towards early diagnosis and the development of sensitive diagnostic and progression biomarkers for MSA, offer new hope for patients.

The Movement Disorder Society Criteria for the Diagnosis of Multiple System Atrophy

BACKGROUND

The second consensus criteria for the diagnosis of multiple system atrophy (MSA) are widely recognized as the reference standard for clinical research, but lack sensitivity to diagnose the disease at early stages.

OBJECTIVE

To develop novel Movement Disorder Society (MDS) criteria for MSA diagnosis using an evidence-based and consensus-based methodology.

METHODS

We identified shortcomings of the second consensus criteria for MSA diagnosis and conducted a systematic literature review to answer predefined questions on clinical presentation and diagnostic tools relevant for MSA diagnosis. The criteria were developed and later optimized using two Delphi rounds within the MSA Criteria Revision Task Force, a survey for MDS membership, and a virtual Consensus Conference.

RESULTS

The criteria for neuropathologically established MSA remain unchanged. For a clinical MSA diagnosis a new category of clinically established MSA is introduced, aiming for maximum specificity with acceptable sensitivity. A category of clinically probable MSA is defined to enhance sensitivity while maintaining specificity. A research category of possible prodromal MSA is designed to capture patients in the earliest stages when symptoms and signs are present, but do not meet the threshold for clinically established or clinically probable MSA. Brain magnetic resonance imaging markers suggestive of MSA are required for the diagnosis of clinically established MSA. The number of research biomarkers that support all clinical diagnostic categories will likely grow.

CONCLUSIONS

This set of MDS MSA diagnostic criteria aims at improving the diagnostic accuracy, particularly in early disease stages. It requires validation in a prospective clinical and a clinicopathological study. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Different phenoconversion pathways in pure autonomic failure with versus without Lewy bodies

Pure autonomic failure (PAF) is a rare disease in which chronic neurogenic orthostatic hypotension (nOH) dominates the clinical picture. Longitudinal studies have reported that PAF can phenoconvert to a central synucleinopathy with motor or cognitive involvement-i.e., to Parkinson disease (PD), dementia with Lewy bodies (DLB), or multiple system atrophy (MSA). These studies have classified patients clinically as having PAF based on nOH without an identified secondary cause or clinical evidence of motor or cognitive impairment due to central neurodegeneration. This approach lumps together two nOH syndromes that are pathologically and neurochemically distinct. One is characterized by intraneuronal cytoplasmic alpha-synuclein aggregates (i.e., Lewy bodies) and degeneration of postganglionic sympathetic neurons, as in PD and DLB; the other is not, as in MSA. Clinical and postmortem data show that the form of PAF that involves sympathetic intraneuronal synucleinopathy and noradrenergic deficiency can phenoconvert to PD or DLB-but not to MSA. Conversely, PAF without these features leaves open the possibility of premotor MSA.