title: Gait initiation impairments in both Essential Tremor and Parkinson's disease.
abstract: Gait initiation is a transitional task involving a voluntary shift from a static, stable position to a relatively less-stable state of locomotion. During gait initiation, anticipatory postural adjustments precede stepping in order to generate forward momentum while balance is maintained. While deficits in gait initiation are frequently reported for persons with Parkinson's disease, there is a paucity of information regarding gait initiation performance in persons with Essential Tremor. We investigated anticipatory postural adjustments and spatiotemporal characteristics of gait initiation in persons with Essential Tremor and compared them to persons with Parkinson's disease as well as age-matched neurologically healthy adults. Twenty-four persons with Essential Tremor, 31 persons with Parkinson's disease, and 38 age-matched controls participated. We compared anterior-posterior and mediolateral center of pressure movements and spatiotemporal stepping characteristics during gait initiation among the three groups using Mann-Whitney U-tests with Bonferroni corrections for multiple comparisons and one-way ANOVAs. Persons with Parkinson's disease demonstrated significantly reduced displacement and velocity of the center of pressure during early phases of anticipatory postural adjustments relative to controls. Displacement of the center of pressure was also reduced in persons with Essential Tremor, although at a later stage of the gait initiation process. Persons with Parkinson's disease and Essential Tremor demonstrated similar reductions in step length during gait initiation when compared to controls. Persons with Parkinson's disease and Essential Tremor exhibit different deficits in gait initiation when compared to healthy older adults. Therefore, this study provides further evidence differentiating motor control features in these movement disorders.
authors.affiliation: Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, United States; Center for Movement Disorders and Neurorestoration, University of Florida, Gainesville, FL, United States.
authors.forename: Kristina M
authors.initials: KM
authors.lastname: Fernandez
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Roemmich
authors.forename: Elizabeth L
authors.initials: EL
authors.lastname: Stegemöller
authors.forename: Shinichi
authors.initials: S
authors.lastname: Amano
authors.forename: Amanda
authors.initials: A
authors.lastname: Thompson
authors.forename: Michael S
authors.initials: MS
authors.lastname: Okun
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Hass
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D020329:Essential Tremor / Q000150:complications / Q000503:physiopathology*; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D008875:Middle Aged; D009068:Movement / Q000502:physiology; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology; D011312:Pressure
keywords: Anticipatory postural adjustments; Essential Tremor; Gait initiation; Motor control; Parkinson's disease