title: Postural limits of stability in premanifest and manifest Huntington's disease.
abstract: BACKGROUND
  Huntington's disease (HD) is associated with neuronal death in basal ganglia circuits important for postural control. Despite evidence of postural instability associated with HD, postural control at the limits of stability has not been investigated in this disease.
  
  
  OBJECTIVE
  To use computerized dynamic posturography to measure postural control at the limits of stability during the premanifest and manifest stages of HD.
  
  
  METHODS
  Patients with manifest HD, premanifest gene carriers, and matched controls stood on mechanically locked force plates while viewing a computer screen. The participant's estimated center of gravity was represented on the screen as a cursor along with eight target icons arranged in a circular pattern at the theoretical edge of limits of stability. On each trial, one of the eight targets was highlighted and the participant was instructed to control the cursor by rapidly shifting his/her weight in the direction of the target. Measures included reaction time, movement velocity, endpoint excursion, maximum excursion, and directional control.
  
  
  RESULTS
  Analysis of variance revealed significant impairment on endpoint excursion, maximum excursion, and directional control (p≤0.001) in the Huntington's disease group, but not in the premanifest gene carrier group as compared to controls. No differences were found on reaction time or movement velocity measures. Group signal to noise ratios also were examined for the measures.
  
  
  CONCLUSIONS
  HD patients, but not premanifest gene carriers, showed impaired postural control at the limits of stability. Impaired performance in HD patients has potential functional consequences including increased risk of falling during weight-shifting activities.
authors: San Diego State University/University of California - San Diego Joint Doctoral Program in Clinical Psychology, San Diego, CA, USA.
authors: Luis D
authors: LD
authors: Medina
authors: Veterans Affairs, San Diego Health Care System, San Diego, CA, USA Department of Psychiatry, University of California San Diego, San Diego, CA, USA.
authors: Eva
authors: E
authors: Pirogovsky
authors: Department of Psychology, San Diego State University, San Diego, CA, USA.
authors: Danielle
authors: D
authors: Salomonczyk
authors: Department of Neurosciences, University of California - San Diego, La Jolla, CA, USA.
authors: Jody
authors: J
authors: Goldstein
authors: School of Exercise and Nutritional Sciences, San Diego State University, San Diego, CA, USA.
authors: Robert
authors: R
authors: Panzera
authors: Department of Neurosciences, University of California - San Diego, La Jolla, CA, USA.
authors: Shea
authors: S
authors: Gluhm
authors: School of Exercise and Nutritional Sciences, San Diego State University, San Diego, CA, USA.
authors: Roger
authors: R
authors: Simmons
authors: Department of Neurosciences, University of California - San Diego, La Jolla, CA, USA.
authors: Jody
authors: J
authors: Corey-Bloom
authors: San Diego State University/University of California - San Diego Joint Doctoral Program in Clinical Psychology, San Diego, CA, USA Department of Psychology, San Diego State University, San Diego, CA, USA.
authors: Paul E
authors: PE
authors: Gilbert
mesh_terms: D000328:Adult; D000368:Aged; D001479:Basal Ganglia / Q000503:physiopathology*; D016022:Case-Control Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D006816:Huntington Disease / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D004856:Postural Balance / Q000502:physiology*; D062706:Prodromal Symptoms; D059629:Signal-To-Noise Ratio; D055815:Young Adult
keywords: Huntington's disease; balance; limits of stability; posture; posturography