title: Gait initiation in children with Rett syndrome.
abstract: Rett syndrome is an X-linked neurodevelopmental condition mainly characterized by loss of spoken language and a regression of purposeful hand use, with the development of distinctive hand stereotypies, and gait abnormalities. Gait initiation is the transition from quiet stance to steady-state condition of walking. The associated motor program seems to be centrally mediated and includes preparatory adjustments prior to any apparent voluntary movement of the lower limbs. Anticipatory postural adjustments contribute to postural stability and to create the propulsive forces necessary to reach steady-state gait at a predefined velocity and may be indicative of the effectiveness of the feedforward control of gait. In this study, we examined anticipatory postural adjustments associated with gait initiation in eleven girls with Rett syndrome and ten healthy subjects. Muscle activity (tibialis anterior and soleus muscles), ground reaction forces and body kinematic were recorded. Children with Rett syndrome showed a distinctive impairment in temporal organization of all phases of the anticipatory postural adjustments. The lack of appropriate temporal scaling resulted in a diminished impulse to move forward, documented by an impairment in several parameters describing the efficiency of gait start: length and velocity of the first step, magnitude and orientation of centre of pressure-centre of mass vector at the instant of (swing-)toe off. These findings were related to an abnormal muscular activation pattern mainly characterized by a disruption of the synergistic activity of antagonistic pairs of postural muscles. This study showed that girls with Rett syndrome lack accurate tuning of feedforward control of gait.
authors.affiliation: Department of Neurology, University Hospital Würzburg, Würzburg, Germany; Department of Pathophysiology and Transplantation, LAMB Pierfranco & Luisa Mariani, University of Milan, Milan, Italy.
authors.forename: Ioannis Ugo
authors.initials: IU
authors.lastname: Isaias
authors.affiliation: Department of Pathophysiology and Transplantation, LAMB Pierfranco & Luisa Mariani, University of Milan, Milan, Italy; Department of Electronic, Information and Bioengineering, Biomedical Technology Laboratory, TBM Lab, Politecnico di Milano, Milan, Italy.
authors.forename: Mariangela
authors.initials: M
authors.lastname: Dipaola
authors.affiliation: Department of Pathophysiology and Transplantation, LAMB Pierfranco & Luisa Mariani, University of Milan, Milan, Italy.
authors.forename: Marlies
authors.initials: M
authors.lastname: Michi
authors.affiliation: Department of Pathophysiology and Transplantation, LAMB Pierfranco & Luisa Mariani, University of Milan, Milan, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Marzegan
authors.affiliation: Department of Neurology, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Volkmann
authors.affiliation: Fondazione Don Carlo Gnocchi IRCSS, Milan, Italy.
authors.forename: Marina L
authors.initials: ML
authors.lastname: Rodocanachi Roidi
authors.affiliation: Department of Electronic, Information and Bioengineering, Biomedical Technology Laboratory, TBM Lab, Politecnico di Milano, Milan, Italy.
authors.forename: Carlo Albino
authors.initials: CA
authors.lastname: Frigo
authors.affiliation: Department of Pathophysiology and Transplantation, LAMB Pierfranco & Luisa Mariani, University of Milan, Milan, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Cavallari
mesh_terms: D001696:Biomechanical Phenomena; D002648:Child; D005260:Female; D005684:Gait; D006801:Humans; D008297:Male; D009043:Motor Activity; D015518:Rett Syndrome / Q000503:physiopathology*
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