Endophenotyping in idiopathic adult onset cervical dystonia

Kägi, Georg; Ruge, Diane; Brugger, Florian; Katschnig, Petra; Sauter, Rafael; Fiorio, Mirta; Tinazzi, Michèle; Rothwell, John C.; Bhatia, Kailash P.

doi:10.1016/j.clinph.2017.04.007

Cited by 13 publications

(6 citation statements)

References 46 publications

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“…Additionally, we could not demonstrate any changes in SICI following the administration of PAS in the three patient groups. These observations are in line with several reports of SICI being within the normal range in dystonic patients . This might be explained, to some degree, by the fact that SICI and PAS exhibit large intra‐ and interindividual variability .…”

Section: Discussionsupporting

confidence: 92%

“…These observations are in line with several reports of SICI being within the normal range in dystonic patients. 29,41,[60][61][62] This might be explained, to some degree, by the fact that SICI and PAS exhibit large intra-and interindividual variability. 25,[63][64][65] Furthermore, it is possible that the sample size is too small to identify statistical differences in these techniques.…”

Section: Discussionmentioning

confidence: 99%

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Temporal Discrimination is Altered in Patients With Isolated Asymmetric and Jerky Upper Limb Tremor

et al. 2019

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A BS TRACT: Background: Unilateral or very asymmetric upper limb tremors with a jerky appearance are poorly investigated. Their clinical classification is an unsolved problem because their classification as essential tremor versus dystonic tremor is uncertain. To avoid misclassification as essential tremor or premature classification as dystonic tremor, the term indeterminate tremor was suggested. Objectives: The aim of this study was to characterize this tremor subgroup electrophysiologically and evaluate whether diagnostically meaningful electrophysiological differences exist compared to patients with essential tremor and dystonic tremor. Methods: We enrolled 29 healthy subjects and 64 patients with tremor: 26 with dystonic tremor, 23 with essential tremor, and 15 patients with upper limb tremor resembling essential tremor but was unusually asymmetric and jerky (indeterminate tremor). We investigated the somatosensory temporal discrimination threshold, the short-interval intracortical inhibition, and the cortical plasticity by paired associative stimulation.Results: Somatosensory temporal discrimination threshold was significantly increased in patients with dystonic tremor and indeterminate tremor, but it was normal in the essential tremor patients and healthy controls. Significant differences in short-interval intracortical inhibition and paired associative stimulation were not found among the three patient groups and controls. Conclusion: These results indicate that indeterminate tremor, as defined in this study, shares electrophysiological similarities with dystonic tremor rather than essential tremor. Therefore, we propose that indeterminate tremor should be considered as a separate clinical entity from essential tremor and that it might be dystonic in nature. Somatosensory temporal discrimination appears to be a useful tool in tremor classification.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Temporal Discrimination is Altered in Patients With Isolated Asymmetric and Jerky Upper Limb Tremor

et al. 2019

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“…28,29 Moreover, the involvement of associative parietal regions implicates a dysfunction of multimodal sensory integration processes as previously suggested. [30][31][32] This could be related to the presence of multiple sensory symptoms in the adult-onset focal dystonia, 33,34 but also to the disruption of the spatial and temporal discrimination (multimodal affected more than unimodal one) 35 and altered body scheme 36 described in these patients. Also, the motor response inhibition disruption related to the right inferior frontal gyrus atrophy 37 in our NTSD patients might contribute to continuous (stereotyped) motor behaviors, such as head positioning or increased blinking.…”

Section: Cortical Alterationsmentioning

confidence: 99%

Brain Structural Changes in Focal Dystonia—What About Task Specificity? A Multimodal MRI Study

et al. 2020

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Background The neural basis of task specificity in dystonia is still poorly understood. This study investigated gray and white matter (WM) brain alterations in patients with task‐specific dystonia (TSD) and non‐task‐specific dystonia (NTSD). Methods Thirty‐six patients with TSD (spasmodic dysphonia, writer's cramp), 61 patients with NTSD (blepharospasm, cervical dystonia), and 83 healthy controls underwent 3D T1‐weighted and diffusion tensor magnetic resonance imaging (MRI). Whole brain cortical thickness and voxel‐based morphometry; volumes of basal ganglia, thalamus, nucleus accumbens, amygdala, and hippocampus; and WM damage were assessed. Analysis of variance models were used to compare MRI measures between groups, adjusting for age and botulinum toxin (BoNT) treatment. Results The comparison between focal dystonia patients showed cortical thickness and gray matter (GM) volume differences (ie, decreased in NTSD, increased in TSD) in frontal, parietal, temporal, and occipital cortical regions; basal ganglia; thalamus; hippocampus; and amygdala. Cerebellar atrophy was found in NTSD patients relative to controls. WM damage was more severe and widespread in task‐specific relative to NTSD patients. TSD patients receiving BoNT, relative to nontreated patients, had cortical thickening and increased GM volume in frontoparietal, temporal, and occipital regions. NTSD patients experiencing pain showed cortical thickening of areas involved in pain‐inhibitory mechanisms. Conclusions TSD and NTSD are characterized by opposite alterations of the main cortical and subcortical sensorimotor and cognitive‐controlling brain structures, suggesting the possible presence of different pathophysiological and/or compensatory mechanisms underlying the complexity of the two clinical phenotypes of focal dystonia. © 2020 International Parkinson and Movement Disorder Society

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“…107 Despite the impressive number of papers that report reduced SICI in dystonia, several others have found it to be within the normal range (Table 1). 95,[108][109][110][111] Some discrepancies between studies could be the result of the large interindividual variability of SICI, which has only moderate reliability, 7,8 as well as subtle methodological differences. Nevertheless, despite its reduction, the role played by SICI in dystonia is still unclear.…”

Section: Variability In Motor Cortical Inhibitionmentioning

confidence: 99%

The interindividual variability of transcranial magnetic stimulation effects: Implications for diagnostic use in movement disorders

et al. 2019

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Background A large number of methods have been described that use transcranial magnetic stimulation to probe the physiology of the human motor cortex. Since the 1990s, hundreds of papers have used them to investigate neurophysiological signatures of different types of movement disorders. However, in recent years there has been increasing recognition of the interindividual variability of these measures and a focus on estimating their reliability and reproducibility. Although this work has been carried out in healthy individuals, it is highly relevant to movement disorders because it may impact the validity of some accepted (“canonical”) neurophysiological biomarkers. The aim of this review is to reexamine the diagnostic usefulness of transcranial magnetic stimulation methods in movement disorders in the context of present knowledge of methodological variability. Methods We conducted a search of the PubMed database for research and review articles on transcranial magnetic stimulation and its diagnostic utility in movement disorders (specifically Parkinson's disease and atypical parkinsonism, dystonia, Tourette syndrome and other chronic tic disorders, Huntington's disease, and essential tremor). We highlighted contradictions in the literature and common misconceptions with the aim of providing a clearer picture of the reliability of these measures in differential diagnosis of movement disorders. Conclusion Although there is no doubt that these studies have provided useful insight into the pathophysiology of movement disorders, there is a clear disagreement among many studies that questions the validity of some of the so called “canonical” findings as diagnostic markers. However, useful findings remain and even those with higher variability can be used to support clinical diagnosis in selected cases. © 2019 International Parkinson and Movement Disorder Society

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Endophenotyping in idiopathic adult onset cervical dystonia

Cited by 13 publications

References 46 publications

Temporal Discrimination is Altered in Patients With Isolated Asymmetric and Jerky Upper Limb Tremor

Temporal Discrimination is Altered in Patients With Isolated Asymmetric and Jerky Upper Limb Tremor

Brain Structural Changes in Focal Dystonia—What About Task Specificity? A Multimodal MRI Study

The interindividual variability of transcranial magnetic stimulation effects: Implications for diagnostic use in movement disorders

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