title: Arm-trunk coordination as a measure of vestibulospinal efficiency.
abstract: When arm and trunk segments are involved in reaching for objects within arm's reach, vestibulospinal pathways compensate for trunk motion influence on arm movement. This compensatory arm-trunk synergy is characterised by a gain coefficient of 0 to 1. Vestibular patients have less efficient arm-trunk synergies and lower gains. To assess the clinical usefulness of the gain measure, we used a portable ultrasound-based device to characterize arm-trunk coordination deficits in vestibular patients. Arm-trunk coordination without vision was measured in a Stationary Hand Task where hand position was maintained during trunk movement, and a Reaching Task with and without trunk motion. Twenty unilateral vestibular patients and 16 controls participated. For the Stationary Hand task, patient gains ranged from g=0.94 (good compensation) to 0.31 (poor compensation) and, on average, were lower than in controls (patients: 0.67 ± 0.19; controls: 0.85 ± 0.07; p< 0.01). Gains were significantly correlated with clinical tests (Sensory Organization; r=0.62, p< 0.01, Foam Romberg Eyes Closed; r=0.65, p< 0.01). For the Reaching Task, blocking trunk movement during reaching modified hand position significantly more in patients (8.2 ± 4.3 cm) compared to controls (4.5 ± 1.7 cm, p< 0.02) and the amount of hand position deviation was correlated with the degree of vestibular loss in a sub-group (n=14) of patients. Measurement of the Stationary Task arm-trunk gain and hand deviations during the Reaching Task can help characterize sensorimotor problems in vestibular-deficient patients and track recovery following therapeutic interventions. The ultrasound-based portable device is suitable for measuring vestibulospinal deficits in arm-trunk coordination in a clinical setting.
authors.affiliation: Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada CRIR Research Centre - Jewish Rehabilitation Hospital, Laval, QC, Canada.
authors.forename: Tafadzwa M
authors.initials: TM
authors.lastname: Sibindi
authors.forename: Tal
authors.initials: T
authors.lastname: Krasovsky
authors.forename: Anatol G
authors.initials: AG
authors.lastname: Feldman
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Dannenbaum
authors.forename: Anthony
authors.initials: A
authors.lastname: Zeitouni
authors.forename: Mindy F
authors.initials: MF
authors.lastname: Levin
mesh_terms: D000328:Adult; D000368:Aged; D001132:Arm / Q000502:physiology*; D001696:Biomechanical Phenomena; D003627:Data Interpretation, Statistical; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009048:Motor Skills / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology; D015203:Reproducibility of Results; D013131:Spine / Q000502:physiology*; D013909:Thorax / Q000502:physiology*; D014465:Ultrasonics; D015837:Vestibular Diseases / Q000175:diagnosis / Q000503:physiopathology; D014722:Vestibule, Labyrinth / Q000502:physiology*
keywords: Motor control; arm-trunk coordination; measurement; rehabilitation; vestibular deficiency