title: Identification of the neural component of torque during manually-applied spasticity assessments in children with cerebral palsy.
abstract: Clinical assessment of spasticity is compromised by the difficulty to distinguish neural from non-neural components of increased joint torque. Quantifying the contributions of each of these components is crucial to optimize the selection of anti-spasticity treatments such as botulinum toxin (BTX). The aim of this study was to compare different biomechanical parameters that quantify the neural contribution to ankle joint torque measured during manually-applied passive stretches to the gastrocsoleus in children with spastic cerebral palsy (CP). The gastrocsoleus of 53 children with CP (10.9 ± 3.7 y; females n = 14; bilateral/unilateral involvement n = 28/25; Gross Motor Functional Classification Score I-IV) and 10 age-matched typically developing (TD) children were assessed using a manually-applied, instrumented spasticity assessment. Joint angle characteristics, root mean square electromyography and joint torque were simultaneously recorded during passive stretches at increasing velocities. From the CP cohort, 10 muscles were re-assessed for between-session reliability and 19 muscles were re-assessed 6 weeks post-BTX. A parameter related to mechanical work, containing both neural and non-neural components, was compared to newly developed parameters that were based on the modeling of passive stiffness and viscosity. The difference between modeled and measured response provided a quantification of the neural component. Both types of parameters were reliable (ICC > 0.95) and distinguished TD from spastic muscles (p < 0.001). However, only the newly developed parameters significantly decreased post-BTX (p = 0.012). Identifying the neural and non-neural contributions to increased joint torque allows for the development of individually tailored tone management.
authors.affiliation: University Hospital Pellenberg, Clinical Motion Analysis Laboratory, University Hospital, Leuven, Belgium; KU Leuven Department of Rehabilitation Sciences, Leuven, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Bar-On
authors.affiliation: University Hospital Pellenberg, Clinical Motion Analysis Laboratory, University Hospital, Leuven, Belgium; KU Leuven Department of Rehabilitation Sciences, Leuven, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Desloovere
authors.affiliation: University Hospital Pellenberg, Clinical Motion Analysis Laboratory, University Hospital, Leuven, Belgium; KU Leuven Department of Development and Regeneration, Leuven, Belgium; University Hospital Pellenberg, Department of Orthopedics, Leuven, Belgium.
authors.forename: G
authors.initials: G
authors.lastname: Molenaers
authors.affiliation: Department of Rehabilitation Medicine, MOVE Research Institute Amsterdam, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Harlaar
authors.affiliation: KU Leuven Department of Rehabilitation Sciences, Leuven, Belgium.
authors.forename: T
authors.initials: T
authors.lastname: Kindt
authors.affiliation: KU Leuven Department of Mechanical Engineering, Leuven, Belgium.
authors.forename: E
authors.initials: E
authors.lastname: Aertbeliën
mesh_terms: D000293:Adolescent; D000843:Ankle Joint / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D019274:Botulinum Toxins, Type A / Q000627:therapeutic use; D016022:Case-Control Studies; D002547:Cerebral Palsy / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D009128:Muscle Spasticity / Q000188:drug therapy / Q000503:physiopathology; D009465:Neuromuscular Agents / Q000627:therapeutic use; D015203:Reproducibility of Results; D019415:Torque
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A
keywords: Botulinum toxin-A; Cerebral palsy; Hypertonia; Muscle modeling; Spasticity; Torque