Movement disorders : official journal of the Movement Disorder Society
-
Multiple system atrophy (MSA) is a sporadic adult-onset neurodegenerative disorder of unknown etiology clinically characterized by a combination of parkinsonian, pyramidal, and cerebellar signs. Levodopa-unresponsive parkinsonism is present in 80% of MSA cases, and this dominant clinical presentation (MSA-P) is associated with a combined degeneration of the substantia nigra pars compacta and the striatum in anatomically related areas. The limited knowledge of the pathophysiology of MSA and the lack of therapeutic strategies prompted the development of lesion models reproducing striatonigral degeneration, the substrate of levodopa-unresponsive parkinsonism in MSA-P. ⋯ In mice, although MPTP reduced the subsequent sensitivity to 3-NP in a sequential lesion, simultaneous nigral and striatal insults were shown to exacerbate striatal damage. MPTP-treated monkeys displayed a significant worsening of parkinsonism and a loss of levodopa-responsiveness after the appearance of hindlimb dystonia and striatal lesion formation induced by subsequent 3-NP intoxication. The different species and intoxication paradigms used will be useful to investigate functional changes in substantia nigra and striatum and to define neuroprotective, neurorestorative, or symptomatic therapeutic strategies.
-
Dementia with Lewy bodies (DLB) is the second most common cause of neurodegenerative dementia in older people that has only been recognized in the past decade and that remains widely underdiagnosed. At postmortem examination, affected patients show numerous alpha-synuclein-positive Lewy bodies (LB) in many parts of the cerebral cortex, particularly neocortical and limbic areas in addition to the nigral LB degeneration characteristic of Parkinson's disease (PD). Clinical presentation, unlike PD, is with progressive cognitive decline with particular deficits of visuospatial ability as well as frontal executive function accompanied by usually only mildly to moderately severe parkinsonism, which is often akineto-rigid without the classical parkinsonian rest-tremor. ⋯ Ancillary investigations, particularly neuroimaging, can aid in differential diagnosis. We review the present state of the best practice in the clinical diagnosis of DLB. Future modifications of diagnostic criteria would ideally include the full range of clinical presentations that can be associated with LB disease.
-
Multiple system atrophy (MSA), a sporadic progressive synucleinopathy of advanced age, is separated into two clinic opathological subtypes: MSA-P (striatonigral degeneration [SND]) with predominant parkinsonian features and MSA-C (olivopontocerebellar atrophy [OPCA]) with predominant cerebellar ataxia. We propose a novel morphological grading system for both subtypes to compare lesion intensities and their possible clinical validity. Forty-two autopsy cases of MSA were separated into four grades (SND 0-III and OPCA 0-III) based on semiquantitative assessment of neuronal loss, astrogliosis, and presence of alpha-synuclein-positive glial cytoplasmic inclusions (GCI) in striatum, globus pallidus, substantia nigra, pontine basis, cerebellum, and inferior olives. ⋯ Parkinsonism was infrequent in MSA-C even when OPCA was associated with SND, suggesting a masking effect by cerebellar system involvement. High terminal Hoehn and Yahr stages were more frequent in MSA-P (P < 0.01), some with good-to-moderate initial levodopa (L-dopa) response. Although the proposed morphological grading of both MSA-P and -C correlates well with initial symptoms and clinical key features of both types, further prospective studies are required to validate the clinical utility of the proposed MSA grading scales for future intervention studies.