The pathophysiological basis of dystonias.

Department of Neurology and Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA.
Nature Reviews Neuroscience 04/2008; 9(3):222-34. DOI: 10.1038/nrn2337
Source: PubMed

ABSTRACT Dystonias comprise a group of movement disorders that are characterized by involuntary movements and postures. Insight into the nature of neuronal dysfunction has been provided by the identification of genes responsible for primary dystonias, the characterization of animal models and functional evaluations and in vivo brain imaging of patients with dystonia. The data suggest that alterations in neuronal development and communication within the brain create a susceptible substratum for dystonia. Although there is no overt neurodegeneration in most forms of dystonia, there are functional and microstructural brain alterations. Dystonia offers a window into the mechanisms whereby subtle changes in neuronal function, particularly in sensorimotor circuits that are associated with motor learning and memory, can corrupt normal coordination and lead to a disabling motor disorder.

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    ABSTRACT: Dystonia is a movement disorder of both genetic and non-genetic causes, which typically results in twisted posturing due to abnormal muscle contraction. Evidence from dystonia patients and animal models of dystonia indicate a crucial role for the striatal cholinergic system in the pathophysiology of dystonia. In this review, we focus on striatal circuitry and the centrality of the acetylcholine system in the function of the basal ganglia in the control of voluntary movement and ultimately clinical manifestion of movement disorders. We consider the impact of cholinergic interneurons (ChIs) on dopamine-acetylcholine interactions and examine new evidence for impairment of ChIs in dysfunction of the motor systems producing dystonic movements, particularly in animal models. We have observed paradoxical excitation of ChIs in the presence of dopamine D2 receptor agonists and impairment of striatal synaptic plasticity in a mouse model of DYT1 dystonia, which are improved by administration of recently developed M1 receptor antagonists. These findings have been confirmed across multiple animal models of DYT1 dystonia and may represent a common endophenotype by which to investigate dystonia induced by other types of genetic and non-genetic causes and to investigate the potential effectiveness of pharmacotherapeutics and other strategies to improve dystonia. Copyright © 2015. Published by Elsevier Ltd.
    Progress in Neurobiology 02/2015; DOI:10.1016/j.pneurobio.2015.02.002 · 10.30 Impact Factor
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    ABSTRACT: Alteration of basal ganglia-thalamocortical circuit has been hypothesized to play a role in the pathophysiology underlying paroxysmal kinesigenic dyskinesia (PKD). We investigated macrostructural and microstructural changes in PKD patients using structural and diffusion tensor magnetic resonance imaging (MRI) analyses. Twenty-five patients with idiopathic PKD and 25 control subjects were prospectively studied on a 3T magnetic resonance (MR) scanner. Cortical thickness analysis was used to evaluate cortical gray matter (GM) changes, and automated volumetry and shape analysis were used to assess volume changes and shape deformation of the subcortical GM structures, respectively. Tract-based spatial statistics (TBSS) was used to evaluate white matter integrity changes in a whole-brain manner, and region-of-interest (ROI) analysis of diffusion tensor metrics was performed in subcortical GM structures. Compared to controls, PKD patients exhibited a reduction in volume of bilateral thalami and regional shape deformation mainly localized to the anterior and medial aspects of bilateral thalami. TBSS revealed an increase in fractional anisotropy (FA) of bilateral thalami and right anterior thalamic radiation in patients relative to controls. ROI analysis also showed an increase in FA of bilateral thalami in patients compared to controls. We have shown evidence for thalamic abnormalities of volume reduction, regional shape deformation, and increased FA in patients with PKD. Our novel findings of concomitant macrostructural and microstructural abnormalities in the thalamus lend further support to previous observations indicating causal relationship between a preferential lesion in the thalamus and development of PKD, thus providing neuroanatomical basis for the involvement of thalamus within the basal ganglia-thalamocortical pathway in PKD. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.
    Human Brain Mapping 12/2014; DOI:10.1002/hbm.22713 · 6.92 Impact Factor
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    ABSTRACT: Introduction Early onset isolated dystonia (DYT1) is linked to a three base pair deletion (ΔGAG) mutation in the TOR1A gene. Clinical manifestation includes intermittent muscle contraction leading to twisting movements or abnormal postures. Neuropathological studies on DYT1 cases are limited, most showing no significant abnormalities. In one study, brainstem intraneuronal inclusions immunoreactive for ubiquitin, torsinA and lamin A/C were described. Using the largest series reported to date comprising 7 DYT1 cases, we aimed to identify consistent neuropathological features in the disease and determine whether we would find the same intraneuronal inclusions as previously reported. Result The pathological changes of brainstem inclusions reported in DYT1 dystonia were not replicated in our case series. Other anatomical regions implicated in dystonia showed no disease-specific pathological intracellular inclusions or evidence of more than mild neuronal loss. Conclusion Our findings suggest that the intracellular inclusions described previously in DYT1 dystonia may not be a hallmark feature of the disorder. In isolated dystonia, DYT1 in particular, biochemical changes may be more relevant than the morphological changes. Electronic supplementary material The online version of this article (doi:10.1186/s40478-014-0159-x) contains supplementary material, which is available to authorized users.
    10/2014; 2(1). DOI:10.1186/s40478-014-0159-x


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