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Correa-Vela M, Carvalho J, Ferrero-Turrion J, Cazurro-Gutiérrez A, Vanegas M, Gonzalez V, Alvárez R, Marcé-Grau A, Moreno A, Macaya-Ruiz A, Pérez-Dueñas B. Early recognition of SGCE-myoclonus-dystonia in children. Dev Med Child Neurol 2023; 65:207-214. [PMID: 35723607 DOI: 10.1111/dmcn.15298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/20/2022] [Accepted: 05/03/2022] [Indexed: 01/09/2023]
Abstract
AIM To evaluate early dystonic features in children and adolescents with SGCE-myoclonus-dystonia. METHOD In this cross-sectional study, 49 patients (26 females and 23 males) with SGCE-myoclonus-dystonia (aged 15y 2mo, SD 12y) with childhood-onset (2y 10mo, SD 1y 10mo) dystonia were examined using a standardized video recorded protocol. Dystonia was rated using the Writer's Cramp and Gait Dystonia Rating Scales. Disability and impairment for handwriting and walking were also rated. RESULTS Dystonia was present at rest (n=1), posture (n=12), and during specific motor tasks (n=45) such as writing (n=35), walking (n=23), and running (n=20). Most children reported disability while performing these tasks. Early dystonic patterns were identified for writer's cramp and gait dystonia, the latter named the 'circular shaking leg', 'dragging leg', and 'hobby-horse gait' patterns. Sensory tricks were used by five and eight children to improve dystonia and myoclonus during writing and walking respectively. The rating scales accurately measured the severity of action dystonia and correlated with self-reported disability. INTERPRETATION Children with SGCE-myoclonus-dystonia show recognizable dystonic patterns and sensory tricks that may lead to an early diagnosis and timely therapeutic approach. Isolated writer's cramp is a key feature in childhood and should prompt SCGE analysis. The proposed action dystonia scales could be used to monitor disease course and response to treatment. WHAT THIS PAPER ADDS Most children with SGCE-myoclonus-dystonia got writer's cramp and had walking and running dystonia. Writer's cramp was a key feature and should prompt SGCE genetic investigation. 'Circular shaking leg', 'dragging leg', and 'hobby-horse gait' were recognized as early gait patterns. Children used sensory tricks to improve myoclonus and dystonia, suggesting common pathophysiological mechanisms. Action dystonia rating scales are valid tools to assess severity in children.
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Affiliation(s)
- Marta Correa-Vela
- Department of Pediatric Neurology, Vall d'Hebron Hospital Universitari, Pediatric.,Departament de Pediatria, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Joao Carvalho
- Pediatric Neurology, Centro de Desenvolvimento da Criança Torrado da Silva, Hospital Garcia de Orta. Almada, Portugal
| | | | | | - Maria Vanegas
- Department of Pediatric Neurology, Vall d'Hebron Hospital Universitari, Pediatric.,Paediatric Department, Evelina Children's Hospital, London, UK
| | | | - Ramiro Alvárez
- Department of Neurology, Hospital Germans Trias, Barcelona, Spain
| | - Anna Marcé-Grau
- Department of Pediatric Neurology, Vall d'Hebron Hospital Universitari, Pediatric
| | - Antonio Moreno
- Departament de Pediatria, Universitat Autònoma de Barcelona, Barcelona, Spain.,Department of Pediatrics, Vall d'Hebron Barcelona Hospital Campus, Barcelona, Spain.,CIBER of Rare Diseases (CIBERER), Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Alfons Macaya-Ruiz
- Department of Pediatric Neurology, Vall d'Hebron Hospital Universitari, Pediatric.,Departament de Pediatria, Universitat Autònoma de Barcelona, Barcelona, Spain.,Neurology Research Group, Vall d'Hebron Research Institute, Barcelona, Spain
| | - Belén Pérez-Dueñas
- Department of Pediatric Neurology, Vall d'Hebron Hospital Universitari, Pediatric.,Departament de Pediatria, Universitat Autònoma de Barcelona, Barcelona, Spain.,CIBER of Rare Diseases (CIBERER), Instituto de Salud Carlos III (ISCIII), Madrid, Spain.,Neurology Research Group, Vall d'Hebron Research Institute, Barcelona, Spain
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Bukhari-Parlakturk N, Lutz M, Al-Khalidi HR, Unnithan S, Wang JEH, Scott B, Termsarasab P, Appelbaum LG, Calakos N. Suitability of Automated Writing Measures for Clinical Trial Outcome in Writer's Cramp. Mov Disord 2023; 38:123-132. [PMID: 36226903 PMCID: PMC9851940 DOI: 10.1002/mds.29237] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/20/2022] [Accepted: 09/13/2022] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Writer's cramp (WC) dystonia is a rare disease that causes abnormal postures during the writing task. Successful research studies for WC and other forms of dystonia are contingent on identifying sensitive and specific measures that relate to the clinical syndrome and achieve a realistic sample size to power research studies for a rare disease. Although prior studies have used writing kinematics, their diagnostic performance remains unclear. OBJECTIVE This study aimed to evaluate the diagnostic performance of automated measures that distinguish subjects with WC from healthy volunteers. METHODS A total of 21 subjects with WC and 22 healthy volunteers performed a sentence-copying assessment on a digital tablet using kinematic and hand recognition softwares. The sensitivity and specificity of automated measures were calculated using a logistic regression model. Power analysis was performed for two clinical research designs using these measures. The test and retest reliability of select automated measures was compared across repeat sentence-copying assessments. Lastly, a correlational analysis with subject- and clinician-rated outcomes was performed to understand the clinical meaning of automated measures. RESULTS Of the 23 measures analyzed, the measures of word legibility and peak accelerations distinguished subjects with WC from healthy volunteers with high sensitivity and specificity and demonstrated smaller sample sizes suitable for rare disease studies, and the kinematic measures showed high reliability across repeat visits, while both word legibility and peak accelerations measures showed significant correlations with the subject- and clinician-rated outcomes. CONCLUSIONS Novel automated measures that capture key aspects of the disease and are suitable for use in clinical research studies of WC dystonia were identified. © 2022 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Noreen Bukhari-Parlakturk
- Department of Neurology, Duke University School of Medicine, Durham, North Carolina, USA
- Duke Institute for Brain Sciences, Duke University School of Medicine, Durham, North Carolina, USA
| | - Michael Lutz
- Department of Neurology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Hussein R. Al-Khalidi
- Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, North Carolina, USA
| | - Shakthi Unnithan
- Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, North Carolina, USA
| | | | - Burton Scott
- Department of Neurology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Pichet Termsarasab
- Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | | | - Nicole Calakos
- Department of Neurology, Duke University School of Medicine, Durham, North Carolina, USA
- Duke Institute for Brain Sciences, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Neurobiology, Duke University School of Medicine, Durham, North Carolina, USA
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3
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Bukhari-Parlakturk N, Frucht SJ. Isolated and combined dystonias: Update. HANDBOOK OF CLINICAL NEUROLOGY 2023; 196:425-442. [PMID: 37620082 DOI: 10.1016/b978-0-323-98817-9.00005-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
Dystonia is a hyperkinetic movement disorder with a unique motor phenomenology that can manifest as an isolated clinical syndrome or combined with other neurological features. This chapter reviews the characteristic features of dystonia phenomenology and the syndromic approach to evaluating the disorders that may allow us to differentiate the isolated and combined syndromes. We also present the most common types of isolated and combined dystonia syndromes. Since accelerated gene discoveries have increased our understanding of the molecular mechanisms of dystonia pathogenesis, we also present isolated and combined dystonia syndromes by shared biological pathways. Examples of these converging mechanisms of the isolated and combined dystonia syndromes include (1) disruption of the integrated response pathway through eukaryotic initiation factor 2 alpha signaling, (2) disease of dopaminergic signaling, (3) alterations in the cerebello-thalamic pathway, and (4) disease of protein mislocalization and stability. The discoveries that isolated and combined dystonia syndromes converge in shared biological pathways will aid in the development of clinical trials and therapeutic strategies targeting these convergent molecular pathways.
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Affiliation(s)
- Noreen Bukhari-Parlakturk
- Department of Neurology, Movement Disorders Division, Duke University (NBP), Durham, NC, United States.
| | - Steven J Frucht
- Department of Neurology, NYU Grossman School of Medicine (SJF), New York, NY, United States
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4
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Zhang L, Hou Y, Lin J, Yang J, Cao B, Wei Q, Ou R, Shang H. Comprehensive analysis of non-motor symptoms and their association with quality of life in Writer's cramp. Parkinsonism Relat Disord 2022; 100:37-40. [PMID: 35700627 DOI: 10.1016/j.parkreldis.2022.05.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 05/15/2022] [Accepted: 05/30/2022] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Limited studies have focused on non-motor symptoms (NMS) in patients with Writer's cramp (WC). The current study aimed to examine the frequency of NMS and their association with health-related quality of life (HR-QoL) in patients with WC. METHODS A total of 80 patients with WC and 69 healthy controls (HCs) were enrolled. Motor symptoms was assessed by Burke-Fahn-Marsden dystonia rating scale and NMS was evaluated through several specific scales, including Hamilton depression rating scale-24 items (HDRS-24), Hamilton anxiety rating scale, Epworth sleepiness scale, Pittsburgh sleep quality index, fatigue severity scale (FSS), numerical rating scale for pain, and Montreal cognitive assessment. The HR-QoL was assessed using 36-item short form health survey (SF-36), which can be divided into physical component summary (PCS) and mental component summary (MCS). Multiple linear regression was used to analysis the association between each NMS and HR-QoL. RESULTS The patients presented more symptoms of depression, anxiety, poor quality of sleep, excessive daytime sleepiness, and fatigue than the HCs. The most frequent NMS in patients with WC was anxiety (51.25%) and depression (46.25%) symptoms. We found that motor symptoms had no association with HR-QoL. Higher scores of HDRS-24 were associated with lower scores of SF-36 in PCS and MCS. Meantime, higher scores of FSS were significantly associated with lower scores of SF-36 in MCS. CONCLUSION The NMS was prevalent in patients with WC, with frequent anxiety and depression symptoms. Depression symptoms and fatigue had a strongly negative impact on HR-QoL and deserve attention in clinic practice.
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Affiliation(s)
- Lingyu Zhang
- Department of Neurology, Laboratory of Neurodegenerative Disorders, Rare Diseases Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Yanbing Hou
- Department of Neurology, Laboratory of Neurodegenerative Disorders, Rare Diseases Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Junyu Lin
- Department of Neurology, Laboratory of Neurodegenerative Disorders, Rare Diseases Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Jing Yang
- Department of Neurology, Laboratory of Neurodegenerative Disorders, Rare Diseases Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Bei Cao
- Department of Neurology, Laboratory of Neurodegenerative Disorders, Rare Diseases Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Qianqian Wei
- Department of Neurology, Laboratory of Neurodegenerative Disorders, Rare Diseases Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Ruwei Ou
- Department of Neurology, Laboratory of Neurodegenerative Disorders, Rare Diseases Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Huifang Shang
- Department of Neurology, Laboratory of Neurodegenerative Disorders, Rare Diseases Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China.
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Ogasawara I, Hattori N, Revankar GS, Konda S, Uno Y, Nakano T, Kajiyama Y, Mochizuki H, Nakata K. Symptom Locus and Symptom Origin Incongruity in Runner's Dystonia - Case Study of an Elite Female Runner. Front Hum Neurosci 2022; 15:809544. [PMID: 34975442 PMCID: PMC8716826 DOI: 10.3389/fnhum.2021.809544] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 11/24/2021] [Indexed: 11/13/2022] Open
Abstract
Objectives: Runner's dystonia is a task-specific dystonia that occurs in the lower limbs and trunk, with diverse symptomatology. We aimed to identify the origin of a dystonic movement abnormality using combined three-dimensional kinematic analysis and electromyographic (EMG) assessment during treadmill running. Participant: A 20-year-old female runner who complained of right-foot collision with the left-leg during right-leg swing-phase, which mimicked right-ankle focal dystonia. Results: Kinematic and EMG assessment of her running motion was performed, which showed a significant drop of the left pelvis during right-leg stance-phase, and a simultaneous increase of right hip adductor muscle activity. This resulted in a pronounced adduction of the entire right lower limb with respect to the pelvis segment. Trajectories of right foot were seen to encroach upon left-leg area. Discussion: These findings suggested that the symptom of this runner was most likely a form of segmental dystonia originating from an impaired control of hip and pelvis, rather than a distal focal ankle dystonia. Conclusion: We conclude that, for individualized symptom assessment, deconstructing the symptom origin from its secondary compensatory movement is crucial for characterizing dystonia. Kinematic and EMG evaluation will therefore be a prerequisite to distinguish symptom origin from secondary compensatory movement.
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Affiliation(s)
- Issei Ogasawara
- Department of Health and Sport Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Noriaki Hattori
- Department of Rehabilitation, Faculty of Medicine, Academic Assembly, University of Toyama, Toyama, Japan
| | - Gajanan S Revankar
- Department of Health and Sport Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan.,Institute for Transdisciplinary Graduate Degree Programs, Osaka University, Osaka, Japan
| | - Shoji Konda
- Department of Health and Sport Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Yuki Uno
- Department of Health and Sport Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Tomohito Nakano
- Department of Neurology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Yuta Kajiyama
- Department of Neurology, Graduate School of Medicine, Osaka University, Osaka, Japan.,Department of Neurology, Sakai City Medical Center, Osaka, Japan
| | - Hideki Mochizuki
- Department of Neurology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Ken Nakata
- Department of Health and Sport Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan
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Zakin E, Simpson DM. Botulinum Toxin Therapy in Writer's Cramp and Musician's Dystonia. Toxins (Basel) 2021; 13:toxins13120899. [PMID: 34941736 PMCID: PMC8708945 DOI: 10.3390/toxins13120899] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/10/2021] [Accepted: 12/10/2021] [Indexed: 11/18/2022] Open
Abstract
Task-specific focal dystonia is characterized by muscle contraction(s) during a specific task, resulting in abnormal postures or movements. Specifically, writer’s cramp involves the upper extremity during the act of writing. Musician’s dystonia has a highly variable presentation, and thus makes therapeutic options more limited. Treatments include oral pharmacologic agents, neuromodulation, surgery and, most often, botulinum toxin (BoNT) injection. Selection of target muscles for toxin injection continues to be an area of active research for these task-specific movements. We present a review of the literature selected from a predefined search of the MEDLINE and ClinicalTrials.gov databases. We include six controlled studies of botulinum toxin for the management of writer’s cramp and focal task-specific dystonia (FTSD), including musician’s dystonia. Overall, 139 patients were included across all studies, with 99 individuals injected for writer’s cramp and the remaining 40 individuals with FTSD. The age range of all patients was 18–80 years old. We included studies that utilized only the BoNT-A serotype. These studies utilized various severity scales to quantify response to toxin injection, with ratings of instrument or pen control included as subjective ratings. Of the included 139 patients in this review, pooled data for toxin response show that 73% of patients who received the drug demonstrated improvement. Specific techniques for muscle localization and targeting were difficult to study as variable methods were employed. This remains an area of ongoing exploration.
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Affiliation(s)
- Elina Zakin
- Department of Neurology, New York University Grossman School of Medicine, New York, NY 10017, USA
- Correspondence:
| | - David M. Simpson
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA;
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7
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Pateraki G, Anargyros K, Aloizou AM, Siokas V, Bakirtzis C, Liampas I, Tsouris Z, Ziogka P, Sgantzos M, Folia V, Peristeri E, Dardiotis E. Therapeutic application of rTMS in neurodegenerative and movement disorders: A review. J Electromyogr Kinesiol 2021; 62:102622. [PMID: 34890834 DOI: 10.1016/j.jelekin.2021.102622] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 11/08/2021] [Accepted: 11/22/2021] [Indexed: 12/11/2022] Open
Abstract
Transcranial magnetic stimulation (TMS) is a non-invasive form of brain stimulation that makes use of the magnetic field generated when an electric current passes through a magnetic coil placed over the scalp. It can be applied as a single stimulus at a time, in pairs of stimuli, or repetitively in trains of stimuli (repetitive TMS, rTMS). RTMS can induce changes in brain activity, whose after-effects reflect the processes of long-term potentiation and long-term depression, as certain protocols, namely those using low frequencies (≤1 Hz) seem to suppress cortical excitability, while those using high frequencies (>1 Hz) seem to enhance it. It is a technique with very few and mostly mild side-effects, whose effects can persist for long time periods, and as such, it has been studied as a potential treatment option in a multitude of neurodegenerative diseases, including those affecting movement. Although rTMS has received approval as a treatment strategy of only a few aspects in movement disorders in the latest guidelines, its further use seems to also be promising in their context. In this review, we gathered the available literature on the therapeutic application of rTMS in movement disorders, namely Parkinson's disease, Amyotrophic Lateral Sclerosis, Huntington's disease, Dystonia, Tic disorders and Essential Tremor.
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Affiliation(s)
- Georgia Pateraki
- Department of Neurology, University Hospital of Larissa, School of Medicine, University of Thessaly, Larissa, Greece
| | - Konstantinos Anargyros
- Department of Neurology, University Hospital of Larissa, School of Medicine, University of Thessaly, Larissa, Greece
| | - Athina-Maria Aloizou
- Department of Neurology, University Hospital of Larissa, School of Medicine, University of Thessaly, Larissa, Greece
| | - Vasileios Siokas
- Department of Neurology, University Hospital of Larissa, School of Medicine, University of Thessaly, Larissa, Greece
| | - Christos Bakirtzis
- B' Department of Neurology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Ioannis Liampas
- Department of Neurology, University Hospital of Larissa, School of Medicine, University of Thessaly, Larissa, Greece
| | - Zisis Tsouris
- Department of Neurology, University Hospital of Larissa, School of Medicine, University of Thessaly, Larissa, Greece
| | - Pinelopi Ziogka
- Department of Neurology, University Hospital of Larissa, School of Medicine, University of Thessaly, Larissa, Greece
| | - Markos Sgantzos
- Department of Neurology, University Hospital of Larissa, School of Medicine, University of Thessaly, Larissa, Greece
| | - Vasiliki Folia
- Department of Neurology, University Hospital of Larissa, School of Medicine, University of Thessaly, Larissa, Greece
| | - Eleni Peristeri
- Department of Neurology, University Hospital of Larissa, School of Medicine, University of Thessaly, Larissa, Greece
| | - Efthimios Dardiotis
- Department of Neurology, University Hospital of Larissa, School of Medicine, University of Thessaly, Larissa, Greece.
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8
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Goswami JN, Roy S. Writer’s Cramp and Psychosis: An Atypical Presentation of Systemic Lupus Erythematosus. Indian Pediatr 2021. [DOI: 10.1007/s13312-021-2179-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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9
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Huang M, Nibbeling EAR, Lagrand TJ, Souza IA, Groen JL, Gandini MA, Zhang FX, Koelman JHTM, Adir N, Sinke RJ, Zamponi GW, Tijssen MAJ, Verbeek DS. Rare functional missense variants in CACNA1H: What can we learn from Writer's cramp? Mol Brain 2021; 14:18. [PMID: 33478561 PMCID: PMC7819179 DOI: 10.1186/s13041-021-00736-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 01/13/2021] [Indexed: 11/10/2022] Open
Abstract
Writer's cramp (WC) is a task-specific focal dystonia that occurs selectively in the hand and arm during writing. Previous studies have shown a role for genetics in the pathology of task-specific focal dystonia. However, to date, no causal gene has been reported for task-specific focal dystonia, including WC. In this study, we investigated the genetic background of a large Dutch family with autosomal dominant‒inherited WC that was negative for mutations in known dystonia genes. Whole exome sequencing identified 4 rare variants of unknown significance that segregated in the family. One candidate gene was selected for follow-up, Calcium Voltage-Gated Channel Subunit Alpha1 H, CACNA1H, due to its links with the known dystonia gene Potassium Channel Tetramerization Domain Containing 17, KCTD17, and with paroxysmal movement disorders. Targeted resequencing of CACNA1H in 82 WC cases identified another rare, putative damaging variant in a familial WC case that did not segregate. Using structural modelling and functional studies in vitro, we show that both the segregating p.Arg481Cys variant and the non-segregating p.Glu1881Lys variant very likely cause structural changes to the Cav3.2 protein and lead to similar gains of function, as seen in an accelerated recovery from inactivation. Both mutant channels are thus available for re-activation earlier, which may lead to an increase in intracellular calcium and increased neuronal excitability. Overall, we conclude that rare functional variants in CACNA1H need to be interpreted very carefully, and additional studies are needed to prove that the p.Arg481Cys variant is the cause of WC in the large Dutch family.
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Affiliation(s)
- Miaozhen Huang
- Department of Genetics, University Medical Center Groningen, University of Groningen, P.O. box 30 001, 9700 RB, Groningen, The Netherlands
| | - Esther A R Nibbeling
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Tjerk J Lagrand
- Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Ivana A Souza
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Justus L Groen
- Department of Neurosurgery, Leiden University Medical Centre, Leiden, The Netherlands
| | - Maria A Gandini
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Fang-Xiong Zhang
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Johannes H T M Koelman
- Department of Neurology and Clinical Neurophysiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Noam Adir
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion, Israel
| | - Richard J Sinke
- Department of Genetics, University Medical Center Groningen, University of Groningen, P.O. box 30 001, 9700 RB, Groningen, The Netherlands
| | - Gerald W Zamponi
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Marina A J Tijssen
- Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Dineke S Verbeek
- Department of Genetics, University Medical Center Groningen, University of Groningen, P.O. box 30 001, 9700 RB, Groningen, The Netherlands.
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Abstract
Dystonia is by far the most intrusive and invalidating extrapyramidal side effect of potent classical antipsychotic drugs. Antipsychotic drug-induced dystonia is classified in both acute and tardive forms. The incidence of drug-induced dystonia is associated with the affinity to inhibitory dopamine D2 receptors. Particularly acute dystonia can be treated with anticholinergic drugs, but the tardive form may also respond to such antimuscarinic treatment, which contrasts their effects in tardive dyskinesia. Combining knowledge of the pathophysiology of primary focal dystonia with the anatomical and pharmacological organization of the extrapyramidal system may shed some light on the mechanism of antipsychotic drug-induced dystonia. A suitable hypothesis is derived from the understanding that focal dystonia may be due to a faulty processing of somatosensory input, so leading to inappropriate execution of well-trained motor programmes. Neuroplastic alterations of the sensitivity of extrapyramidal medium-sized spiny projection neurons to stimulation, which are induced by the training of specific complex movements, lead to the sophisticated execution of these motor plans. The sudden and non-selective disinhibition of indirect pathway medium-sized spiny projection neurons by blocking dopamine D2 receptors may distort this process. Shutting down the widespread influence of tonically active giant cholinergic interneurons on all medium-sized spiny projection neurons by blocking muscarinic receptors may result in a reduction of the influence of extrapyramidal cortical-striatal-thalamic-cortical regulation. Furthermore, striatal cholinergic interneurons have an important role to play in integrating cerebellar input with the output of cerebral cortex, and are also targeted by dopaminergic nigrostriatal fibres affecting dopamine D2 receptors.
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Affiliation(s)
- Anton JM Loonen
- Groningen Research Institute of Pharmacy, Pharmacotherapy, -Epidemiology and -Economics, University of Groningen, Groningen, The Netherlands
- Geestelijke GezondheidsZorg Westelijk Noord-Brabant (GGZ WNB), Mental Health Hospital, Halsteren, The Netherlands
| | - Svetlana A Ivanova
- Mental Health Research Institute, Tomsk National Research Medical Center of the Russian Academy of Sciences, Tomsk, Russian Federation
- National Research Tomsk Polytechnic University, Tomsk, Russian Federation
- Siberian State Medical University, Tomsk, Russian Federation
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