[Differential diagnosis of parkinsonian syndromes using MRI]

[Diagnostics of Wilson's disease]

Wilson's disease is a rare genetic but treatable metabolic disorder which has a favorable prognosis when diagnosed early and treated adequately. Therefore, knowledge of this rare clinical condition and a reliable diagnosis are indispensable. The diagnostic work-up is initiated in cases of unexplained acute or chronic liver disease and/or an extrapyramidal motor disturbance occurring mostly between the 5th and 45th years of life. Manifestations with initial symptoms have occasionally been observed at an age younger than 1 year and later than 70 years. Immediate biochemical and genetic examinations for early diagnosis are essential. Further test methods, such as liver and transcranial sonography, cerebral magnetic resonance imaging (MRI) and ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG-PET), ¹²³I-beta-CIT and ¹²³I-iodobenzamide (IBZM) single photon emission computed tomography (SPECT), electrophysiology as well as fine motor tests are unspecific but can be used to test for organ damage and for monitoring of progress. Immediate initiation of a therapy is required and justified on the basis of a confirmed diagnosis.

The Differential Diagnosis and Treatment of Atypical Parkinsonism

BACKGROUND

Aside from idiopathic Parkinson syndrome (Parkinson's disease), there are a number of other, so-called atypical parkinsonian syndromes: dementia with Lewy bodies (DLB), multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD). DLB is a common disease, with a prevalence of 0.4% (400 cases per 100 000 persons) in the elderly; MSA and PSP both have a prevalence of 5 to 10 per 100 000 persons, while the prevalence of CBD is about 1 per 100 000.

METHODS

This review is based on pertinent publications retrieved by a selective literature search.

RESULTS

The atypical parkinsonian syndromes are synucleinopathies and tauopathies, i.e., disorders characterized by the abnormal deposition of the proteins α-synuclein and tau. The site of deposition is correlated with the clinical features. In DLB, synuclein is mainly deposited in neocortical neurons, with some brain stem involvement as well. The main clinical features are dementia and, later on, parkinsonism. In MSA, synuclein is deposited in oligodendrocytes, mainly in the cerebellum but also in the brain stem; the main clinical feature is autonomic dysfunction combined with parkinsonism or cerebellar ataxia. Synucleinopathies often impair REM (rapid eye movement) sleep. PSP and CBD, on the other hand, are primary tauopathies. PSP usually causes predominantly supranuclear vertical gaze palsy and early postural instability with falls, less commonly parkinsonism (PSP-P) or frontotemporal dementia (PSP-FTD) as its most prominent feature. CBD typically manifests itself as markedly asymmetrical parkinsonism with apraxia or cortical sensory disturbance. At present, there is no accepted causal treatment for any of these disorders; the available symptomatic treatments are of limited efficacy and are supported only by low-level evidence.

CONCLUSION

Causal treatments for neurodegenerative diseases are now being developed and tested, and thus a molecular diagnosis is desirable. This will require the cooperation of primary care physicians with specialized centers.

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.

Towards translational therapies for multiple system atrophy

Multiple system atrophy (MSA) is a fatal adult-onset neurodegenerative disorder of uncertain etiopathogenesis manifesting with autonomic failure, parkinsonism, and ataxia in any combination. The underlying neuropathology affects central autonomic, striatonigral and olivopontocerebellar pathways and it is associated with distinctive glial cytoplasmic inclusions (GCIs, Papp-Lantos bodies) that contain aggregates of α-synuclein. Current treatment options are very limited and mainly focused on symptomatic relief, whereas disease modifying options are lacking. Despite extensive testing, no neuroprotective drug treatment has been identified up to now; however, a neurorestorative approach utilizing autologous mesenchymal stem cells has shown remarkable beneficial effects in the cerebellar variant of MSA. Here, we review the progress made over the last decade in defining pathogenic targets in MSA and summarize insights gained from candidate disease-modifying interventions that have utilized a variety of well-established preclinical MSA models. We also discuss the current limitations that our field faces and suggest solutions for possible approaches in cause-directed therapies of MSA.