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Movement Disorders : Official Journal... Oct 2023
Topics: Humans; Movement Disorders
PubMed: 37735886
DOI: 10.1002/mds.29584 -
Tremor and Other Hyperkinetic Movements... 2023Functional movement disorders (FMD) are a diagnostic and therapeutic challenge, both to the neurologist and psychiatrists. The phenomenology is varied and can present as... (Review)
Review
BACKGROUND
Functional movement disorders (FMD) are a diagnostic and therapeutic challenge, both to the neurologist and psychiatrists. The phenomenology is varied and can present as tremors, dystonia, jerks/myoclonus, gait disorder, other abnormal movements or a combination. There has been an increase in the use of electrophysiological studies that are an important tool in the evaluation of FMDs.
METHODS
We searched the database platforms of MEDLINE, Google scholar, Web of Sciences, Scopus using the Medical Subject Heading terms (MeSH) for all the articles from 1st January 1970 till November 2022. A total of 658 articles were obtained by the search mechanism. A total of 79 relevant articles were reviewed thoroughly, of which 26 articles that had electrophysiological data were included in the present review.
RESULTS
Variability, distractibility and entertainability can be demonstrated in functional tremors by using multichannel surface electromyography. Voluntary ballistic movements tend to decrease the tremor, while loading the tremulous limb with weight causes the tremor amplitude to increase in functional tremor. Presence of Bereitschaftspotential demonstrates the functional nature of palatal tremor and myoclonus. Co-contraction testing may be helpful in differentiating functional from organic dystonia. The R2 blink reflex recovery cycle has been found to be abnormally enhanced in organic blepharospasm, whereas it is normal in presumed functional blepharospasm. Plasticity is found to be abnormally high in organic dystonia and normal in functional dystonia, in addition to enhanced facilitation in patients with organic dystonia.
CONCLUSIONS
Electrophysiological tests supplement clinical examination and helps in differentiating FMD from organic movement disorders.
Topics: Humans; Tremor; Myoclonus; Dystonia; Blepharospasm; Movement Disorders; Dystonic Disorders; Electrophysiology; Conversion Disorder
PubMed: 38162980
DOI: 10.5334/tohm.793 -
Movement Disorders : Official Journal... Oct 2023Long-term use of levodopa for Parkinson's disease (PD) treatment is often hindered by development of motor complications, including levodopa-induced dyskinesia (LID)....
BACKGROUND
Long-term use of levodopa for Parkinson's disease (PD) treatment is often hindered by development of motor complications, including levodopa-induced dyskinesia (LID). The substantia nigra pars reticulata (SNr) and globus pallidus internal segment (GPi) are the output nuclei of the basal ganglia. Dysregulation of SNr and GPi activity contributes to PD pathophysiology and LID.
OBJECTIVE
The objective of this study was to determine whether direct modulation of SNr GABAergic neurons and SNr projections to the pedunculopontine nucleus (PPN) regulates PD symptoms and LID in a mouse model.
METHODS
We expressed Cre-recombinase activated channelrhodopsin-2 (ChR2) or halorhodopsin adeno-associated virus-2 (AAV2) vectors selectively in SNr GABAergic neurons of Vgat-IRES-Cre mice in a 6-hydroxydopamine model of PD to investigate whether direct optogenetic modulation of SNr neurons or their projections to the PPN regulates PD symptoms and LID expression. The forepaw stepping task, mouse LID rating scale, and open-field locomotion were used to assess akinesia and LID to test the effect of SNr modulation.
RESULTS
Akinesia was improved by suppressing SNr neuron activity with halorhodopsin. LID was significantly reduced by increasing SNr neuronal activity with ChR2, which did not interfere with the antiakinetic effect of levodopa. Optical stimulation of ChR2 in SNr projections to the PPN recapitulated direct SNr stimulation.
CONCLUSIONS
Modulation of SNr GABAergic neurons alters akinesia and LID expression in a manner consistent with the rate model of basal ganglia circuitry. Moreover, the projections from SNr to PPN likely mediate the antidyskinetic effect of increasing SNr neuronal activity, identifying a potential novel role for the PPN in LID. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
Topics: Mice; Animals; Pars Reticulata; Levodopa; Halorhodopsins; Parkinson Disease; GABAergic Neurons; Dyskinesia, Drug-Induced; Substantia Nigra
PubMed: 37461292
DOI: 10.1002/mds.29558 -
Movement Disorders : Official Journal... Aug 2023There is growing clinical and research utilization of genetic testing in Parkinson's disease (PD), including direct-to-consumer testing.
BACKGROUND
There is growing clinical and research utilization of genetic testing in Parkinson's disease (PD), including direct-to-consumer testing.
OBJECTIVES
The aim is to determine the international landscape of genetic testing in PD to inform future worldwide recommendations.
METHODS
A web-based survey assessing current practices, concerns, and barriers to genetic testing and counseling was administered to the International Parkinson and Movement Disorders Society membership.
RESULTS
Common hurdles across sites included cost and access to genetic testing, and counseling, as well as education on genetic counseling. Region-dependent differences in access to and availability of testing and counseling were most notable in Africa. High-income countries also demonstrated heterogeneity, with European nations more likely to have genetic testing covered through insurance than Pan-American and Asian countries.
CONCLUSIONS
This survey highlights not only diversity of barriers in different regions but also the shared and highly actionable needs for improved education and access to genetic counseling and testing for PD worldwide. © 2023 International Parkinson and Movement Disorder Society.
Topics: Humans; Parkinson Disease; Genetic Testing; Counseling
PubMed: 37310233
DOI: 10.1002/mds.29442 -
Annals of Neurology Nov 2023GNAO1-related disorders (OMIM #615473 and #617493), caused by variants in the GNAO1 gene, are characterized by developmental delay or intellectual disability, hypotonia,... (Observational Study)
Observational Study
OBJECTIVE
GNAO1-related disorders (OMIM #615473 and #617493), caused by variants in the GNAO1 gene, are characterized by developmental delay or intellectual disability, hypotonia, movement disorders, and epilepsy. Neither a genotype-phenotype correlation nor a clear severity score have been established for this disorder. The objective of this prospective and retrospective observational study was to develop a severity score for GNAO1-related disorders, and to delineate the correlation between the underlying molecular mechanisms and clinical severity.
METHODS
A total of 16 individuals with GNAO1-related disorders harboring 12 distinct missense variants, including four novel variants (p.K46R, p.T48I, p.R209P, and p.L235P), were examined with repeated clinical assessments, video-electroencephalogram monitoring, and brain magnetic resonance imaging. The molecular pathology of each variant was delineated using a molecular deconvoluting platform.
RESULTS
The patients displayed a wide variability in the severity of their symptoms. This heterogeneity was well represented in the GNAO1-related disorders severity score, with a broad range of results. Patients with the same variant had comparable severity scores, indicating that differences in disease profiles are not due to interpatient variability, but rather, to unique disease mechanisms. Moreover, we found a significant correlation between clinical severity scores and molecular mechanisms.
INTERPRETATION
The clinical score proposed here provides further insight into the correlation between pathophysiology and phenotypic severity in GNAO1-related disorders. We found that each variant has a unique profile of clinical phenotypes and pathological molecular mechanisms. These findings will contribute to better understanding GNAO1-related disorders. Additionally, the severity score will facilitate standardization of patients categorization and assessment of response to therapies in development. ANN NEUROL 2023;94:987-1004.
Topics: Humans; Prospective Studies; Movement Disorders; Epilepsy; Mutation, Missense; GTP-Binding Proteins; GTP-Binding Protein alpha Subunits, Gi-Go
PubMed: 37548038
DOI: 10.1002/ana.26758 -
Cell Reports Dec 2023Heterotrimeric G proteins transduce extracellular chemical messages to generate appropriate intracellular responses. Point mutations in GNAO1, encoding the G protein α...
Heterotrimeric G proteins transduce extracellular chemical messages to generate appropriate intracellular responses. Point mutations in GNAO1, encoding the G protein α subunit, have been implicated in a pathogenic condition characterized by seizures, movement disorders, intellectual disability, and developmental delay (GNAO1 disorder). However, the effects of these mutations on G protein structure and function are unclear. Here, we report the effects of 55 mutations on Gα conformation, thermostability, nucleotide binding, and hydrolysis, as well as interaction with Gβγ subunits, receptors, and effectors. Our effort reveals four functionally distinct groups of mutants, including one group that sequesters receptors and another that sequesters Gβγ, both acting in a genetically dominant manner. These findings provide a more comprehensive understanding of disease-relevant mutations and reveal that GNAO1 disorder is likely composed of multiple mechanistically distinct disorders that will likely require multiple therapeutic strategies.
Topics: Humans; Mutation; Movement Disorders; Point Mutation; GTP-Binding Proteins; GTP-Binding Protein alpha Subunits, Gi-Go
PubMed: 37980565
DOI: 10.1016/j.celrep.2023.113462 -
Movement Disorders : Official Journal... Oct 2023Several lysosomal genes are associated with Parkinson's disease (PD), yet the association between PD and ARSA remains unclear. (Meta-Analysis)
Meta-Analysis
BACKGROUND
Several lysosomal genes are associated with Parkinson's disease (PD), yet the association between PD and ARSA remains unclear.
OBJECTIVES
To study rare ARSA variants in PD.
METHODS
To study rare ARSA variants (minor allele frequency < 0.01) in PD, we performed burden analyses in six independent cohorts with 5801 PD patients and 20,475 controls, followed by a meta-analysis.
RESULTS
We found evidence for associations between functional ARSA variants and PD in four cohorts (P ≤ 0.05 in each) and in the meta-analysis (P = 0.042). We also found an association between loss-of-function variants and PD in the United Kingdom Biobank cohort (P = 0.005) and in the meta-analysis (P = 0.049). These results should be interpreted with caution as no association survived multiple comparisons correction. Additionally, we describe two families with potential co-segregation of ARSA p.E382K and PD.
CONCLUSIONS
Rare functional and loss-of-function ARSA variants may be associated with PD. Further replications in large case-control/familial cohorts are required. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
Topics: Humans; Gene Frequency; Parkinson Disease; United Kingdom; Cerebroside-Sulfatase
PubMed: 37381728
DOI: 10.1002/mds.29521 -
Neurological Sciences : Official... Dec 2023Tremor is the most common movement disorder. Although clinical examination plays a significant role in evaluating patients with tremor, laboratory tests are useful to... (Review)
Review
INTRODUCTION
Tremor is the most common movement disorder. Although clinical examination plays a significant role in evaluating patients with tremor, laboratory tests are useful to classify tremors according to the recent two-axis approach proposed by the International Parkinson and Movement Disorders Society.
METHODS
In the present review, we will discuss the usefulness and applicability of the various diagnostic methods in classifying and diagnosing tremors. We will evaluate a number of techniques, including laboratory and genetic tests, neurophysiology, and neuroimaging. The role of newly introduced innovative tremor assessment methods will also be discussed.
RESULTS
Neurophysiology plays a crucial role in tremor definition and classification, and it can be useful for the identification of specific tremor syndromes. Laboratory and genetic tests and neuroimaging may be of paramount importance in identifying specific etiologies. Highly promising innovative technologies are being developed for both clinical and research purposes.
CONCLUSIONS
Overall, laboratory investigations may support clinicians in the diagnostic process of tremor. Also, combining data from different techniques can help improve understanding of the pathophysiological bases underlying tremors and guide therapeutic management.
Topics: Humans; Tremor; Movement Disorders; Syndrome; Essential Tremor
PubMed: 37814130
DOI: 10.1007/s10072-023-07108-w -
Brain : a Journal of Neurology Aug 2023The advent of clinical trials of disease-modifying agents for neurodegenerative disease highlights the need for evidence-based end point selection. Here we report the...
The advent of clinical trials of disease-modifying agents for neurodegenerative disease highlights the need for evidence-based end point selection. Here we report the longitudinal PROSPECT-M-UK study of progressive supranuclear palsy (PSP), corticobasal syndrome (CBS), multiple system atrophy (MSA) and related disorders, to compare candidate clinical trial end points. In this multicentre UK study, participants were assessed with serial questionnaires, motor examination, neuropsychiatric and MRI assessments at baseline, 6 and 12 months. Participants were classified by diagnosis at baseline and study end, into Richardson syndrome, PSP-subcortical (PSP-parkinsonism and progressive gait freezing subtypes), PSP-cortical (PSP-frontal, PSP-speech and language and PSP-CBS subtypes), MSA-parkinsonism, MSA-cerebellar, CBS with and without evidence of Alzheimer's disease pathology and indeterminate syndromes. We calculated annual rate of change, with linear mixed modelling and sample sizes for clinical trials of disease-modifying agents, according to group and assessment type. Two hundred forty-three people were recruited [117 PSP, 68 CBS, 42 MSA and 16 indeterminate; 138 (56.8%) male; age at recruitment 68.7 ± 8.61 years]. One hundred and fifty-nine completed the 6-month assessment (82 PSP, 27 CBS, 40 MSA and 10 indeterminate) and 153 completed the 12-month assessment (80 PSP, 29 CBS, 35 MSA and nine indeterminate). Questionnaire, motor examination, neuropsychiatric and neuroimaging measures declined in all groups, with differences in longitudinal change between groups. Neuroimaging metrics would enable lower sample sizes to achieve equivalent power for clinical trials than cognitive and functional measures, often achieving N < 100 required for 1-year two-arm trials (with 80% power to detect 50% slowing). However, optimal outcome measures were disease-specific. In conclusion, phenotypic variance within PSP, CBS and MSA is a major challenge to clinical trial design. Our findings provide an evidence base for selection of clinical trial end points, from potential functional, cognitive, clinical or neuroimaging measures of disease progression.
Topics: Male; Humans; Middle Aged; Aged; Female; Parkinsonian Disorders; Supranuclear Palsy, Progressive; Multiple System Atrophy; Magnetic Resonance Imaging; United Kingdom
PubMed: 36975168
DOI: 10.1093/brain/awad105 -
Movement Disorders : Official Journal... Dec 2023Excessive glutamatergic transmission in the striatum is implicated in Parkinson's disease (PD) progression. Astrocytes maintain glutamate homeostasis, protecting from...
BACKGROUND
Excessive glutamatergic transmission in the striatum is implicated in Parkinson's disease (PD) progression. Astrocytes maintain glutamate homeostasis, protecting from excitotoxicity through the glutamate-aspartate transporter (GLAST), whose alterations have been reported in PD. Noninvasive brain stimulation using intermittent theta-burst stimulation (iTBS) acts on striatal neurons and glia, inducing neuromodulatory effects and functional recovery in experimental parkinsonism.
OBJECTIVE
Because PD is associated with altered astrocyte function, we hypothesized that acute iTBS, known to rescue striatal glutamatergic transmission, exerts regional- and cell-specific effects through modulation of glial functions.
METHODS
6-Hydroxydopamine-lesioned rats were exposed to acute iTBS, and the areas predicted to be more responsive by a biophysical, hyper-realistic computational model that faithfully reconstructs the experimental setting were analyzed. The effects of iTBS on glial cells and motor behavior were evaluated by molecular and morphological analyses, and CatWalk and Stepping test, respectively.
RESULTS
As predicted by the model, the hippocampus, cerebellum, and striatum displayed a marked c-FOS activation after iTBS, with the striatum showing specific morphological and molecular changes in the astrocytes, decreased phospho-CREB levels, and recovery of GLAST. Striatal-dependent motor performances were also significantly improved.
CONCLUSION
These data uncover an unknown iTBS effect on astrocytes, advancing the understanding of the complex mechanisms involved in TMS-mediated functional recovery. Data on numerical dosimetry, obtained with a degree of anatomical details never before considered and validated by the biological findings, provide a framework to predict the electric-field induced in different specific brain areas and associate it with functional and molecular changes. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
Topics: Rats; Animals; Astrocytes; Transcranial Magnetic Stimulation; Parkinsonian Disorders; Parkinson Disease; Corpus Striatum; Magnetic Phenomena
PubMed: 37700489
DOI: 10.1002/mds.29599