title: Differences in active range of motion measurements in the upper extremity of patients with writer's cramp compared with healthy controls.
abstract: METHODS
  Exploratory case-control study.
  
  
  BACKGROUND
  Writer's cramp (WC) is a type of focal hand dystonia. The central nervous system plays a role in its pathophysiology, but abnormalities in the affected musculoskeletal components may also be relevant.
  
  
  OBJECTIVE
  We compared the active range of motion (ROM) in patients with WC and healthy volunteers (HVs) and correlated the findings with disease duration and severity.
  
  
  METHODS
  Affected limb joints were measured with goniometers. Patients were assessed at least 3 months after their last botulinum toxin (botulinum neurotoxin) injection, and strength was clinically normal. t tests were used to compare the ROMs of WC with matched HVs. The Spearman correlation coefficient assessed the relationship of active ROMs to the disease duration and handwriting subscore of the Dystonia Disability Scale.
  
  
  RESULTS
  ROMs of D1 metacarpophalangeal (MCP) joint extension as well as D2 and D5 MCP flexion were significantly smaller in WC, and distal interphalangeal joint extension in D3 and D5 was significantly greater compared with HVs. There were negative correlations between D2 MCP flexion and disease duration and with Dystonia Disability Scale.
  
  
  CONCLUSIONS
  Abnormalities in ROMs in WC were found. Severity and disease duration correlated with reduced D2 MCP flexion. This may be related to intrinsic biomechanical abnormalities, co-contraction of muscles, or a combination of subclinical weakness and atrophy from repeated botulinum neurotoxin injections.
  
  
  CONCLUSIONS
  Hand biomechanical properties should not be ignored in the pathophysiology of WC.
  
  
  METHODS
  2c.
authors: Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA; Division of Neurology, Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand. Electronic address: prachaya.srivanitchapoom@nih.gov.
authors: Prachaya
authors: P
authors: Srivanitchapoom
authors: Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA; Department of Neurology, Mid-Atlantic Permanente Research Institute, Kaiser Permanente, Rockville, MD, USA.
authors: Ejaz A
authors: EA
authors: Shamim
authors: Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
authors: Pierre
authors: P
authors: Diomi
authors: Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
authors: Takaaki
authors: T
authors: Hattori
authors: Department of Neurology, Govind Ballabh Pant Hospital, New Delhi, India.
authors: Sanjay
authors: S
authors: Pandey
authors: Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
authors: Sherry
authors: S
authors: Vorbach
authors: Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
authors: Jung E
authors: JE
authors: Park
authors: Clinical Neurosciences Program, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
authors: Tianxia
authors: T
authors: Wu
authors: Clinical Neurosciences Program, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
authors: Sungyoung
authors: S
authors: Auh
authors: Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
authors: Mark
authors: M
authors: Hallett
mesh_terms: D000328:Adult; D000367:Age Factors; D001905:Botulinum Toxins / Q000627:therapeutic use*; D016022:Case-Control Studies; D020821:Dystonic Disorders / Q000175:diagnosis / Q000188:drug therapy* / Q000534:rehabilitation; D004551:Elbow Joint / Q000503:physiopathology; D005260:Female; D005384:Finger Joint / Q000187:drug effects / Q000503:physiopathology; D006801:Humans; D015552:Injections, Intralesional; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000187:drug effects / Q000502:physiology*; D012016:Reference Values; D018570:Risk Assessment; D012720:Severity of Illness Index; D012737:Sex Factors; D016896:Treatment Outcome; D014955:Wrist Joint / Q000503:physiopathology
chemical_list: D001905:Botulinum Toxins
keywords: Biomechanical assessment; Botulinum toxin; Dystonia Disability Scale; Focal hand dystonia; Writer's cramp