title: Trunk muscle involvement is most critical for the loss of balance control in patients with facioscapulohumeral muscular dystrophy.
abstract: BACKGROUND
  Although it is known that muscle weakness is a major cause of postural instability and leads to an increased incidence of falls in patients with neuromuscular disease, the relative contribution of lower extremity and trunk muscle weakness to postural instability has not been studied well.
  
  
  METHODS
  We determined the relationship between muscle fatty infiltration and sagittal-plane balance in ten patients with facioscapulohumeral muscular dystrophy. Sagittal-plane platform translations were imposed in forward and backward directions on patients with facioscapulohumeral muscular dystrophy and healthy controls. Stepping thresholds were determined and kinematic responses and center-of-mass displacements were assessed using 3 dimensional motion analysis. In the patients, magnetic resonance imaging was used to determine the amount of fatty infiltration of trunk and lower extremity muscles.
  
  
  RESULTS
  Stepping thresholds in both directions were decreased in patients compared to controls. In patients, significant correlations were found for fatty infiltration of ventral muscles with backward stepping threshold and for fatty infiltration of dorsal muscles with forward stepping threshold. Fatty infiltration of the rectus abdominis and the back extensors explained the largest part of the variance in backward and forward stepping thresholds, respectively. Center-of-mass displacements were dependent on intensity and direction of perturbation. Kinematic analysis revealed predominant ankle strategies, except in patients with lumbar hyperlordosis.
  
  
  CONCLUSIONS
  These findings indicate that trunk muscle involvement is most critical for loss of sagittal-plane postural balance in patients with facioscapulohumeral muscular dystrophy. This insight may help to develop rehabilitation strategies to prevent these patients from falling.
authors.affiliation: Department of Rehabilitation, Radboud University Medical Centre, Nijmegen, The Netherlands. Electronic address: noortje.rijken@radboudumc.nl.
authors.forename: N H M
authors.initials: NH
authors.lastname: Rijken
authors.affiliation: Department of Neurology, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: B G M
authors.initials: BG
authors.lastname: van Engelen
authors.affiliation: Department of Radiology, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: J W J
authors.initials: JW
authors.lastname: de Rooy
authors.affiliation: Department of Rehabilitation, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: A C H
authors.initials: AC
authors.lastname: Geurts
authors.affiliation: Department of Rehabilitation, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: V
authors.initials: V
authors.lastname: Weerdesteyn
mesh_terms: D000328:Adult; D000368:Aged; D000842:Ankle; D000843:Ankle Joint; D001696:Biomechanical Phenomena; D005260:Female; D020233:Gait Disorders, Neurologic / Q000503:physiopathology*; D006801:Humans; D008141:Lordosis / Q000503:physiopathology; D008159:Lumbar Vertebrae / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness; D018482:Muscle, Skeletal / Q000502:physiology; D020391:Muscular Dystrophy, Facioscapulohumeral / Q000503:physiopathology*; D004856:Postural Balance; D011187:Posture; D060726:Torso / Q000502:physiology*
keywords: Balance; FSHD; Neuromuscular disorders; Postural control