Muscle stiffness and strength and their relation to hand function in children with hemiplegic cerebral palsy

Abstract

This study compared the passive stiffness of wrist flexors and the strength of wrist flexors and extensors in three different wrist positions (30 degrees of flexion, neutral, and 30 degrees of extension) between children with cerebral palsy (CP) and typically developing (TD) comparison children. It also examined associations between these characteristics and manual function in children with CP. Eleven children with spastic hemiplegic CP (six females, five males; mean age 8y 5mo [SD 1y 8mo], range 6-11y) and 11 TD children, matched for age and sex, took part in this study. Passive stiffness of muscles was measured as the torque/angle relation during passive motion. Isometric strength tests were performed and the time needed to complete three tasks based on the Jebsen-Taylor Hand Function Test was recorded. Flexor stiffness was higher in the group with CP. Strength of flexors and extensors in the group with CP was lower with the wrist extended. No difference among test positions was found in the TD group. Moderate correlations were observed between manual function and variables related to strength and stiffness of wrist muscles in the group with CP. Children with CP showed muscle alterations coherent with the use of the wrist in flexion. Intervention on these characteristics could have a positive impact on manual function.

Mechanical properties of the plantarflexor musculotendinous unit during passive dorsiflexion in children with cerebral palsy compared with typically developing children

“…Biomechanical stiffness was considered the primary contributing factor to the significantly shorter delay in these children. In an upper limb study, Vaz et al 11 reported wrist flexor passive stiffness was significantly greater in children with hemiplegic CP than in typically developing children. Friden and Lieber 5 found that flexor carpi ulnaris muscle cells were twice as stiff in biopsy material from children with CP compared with biopsies obtained from a range of muscles in able-bodied adult individuals.…”

“…10 Although the contribution of passive mechanical factors to overall restriction of motion is somewhat ambiguous, some studies have indicated that children with CP demonstrate increased passive stiffness in forearm and hand muscles. 5,11 Given the potential for increased stiffness in plantarflexor muscles to contribute to functional disability, in, for example, walking, it is important to consider the passive mechanical properties of these muscles when determining the causes of ankle joint limitation and functional impairments in ambulant children with CP. The purpose of this study was to explore the relation between plantarflexor muscle length and passive tension in ambulant children aged between 4 and 10 years with and without CP.…”

The role of co-activation in strength and force modulation in the elbow of children with unilateral cerebral palsy

“…Primary neuromuscular impairments like muscle overactivity, muscle weakness, and decreased selective motor control, and secondary musculoskeletal problems like bony malformations and contractures are multiple motor signs that may contribute to the disability (Koman et al, 2004). The presence of muscle weakness in CP is well documented (Ikeda et al, 1998;Wiley and Damiano, 1998;Engsberg et al, 2000;Vaz et al, 2006), and several reports indicate that this weakness is an important contributor to the activity limitations seen in this group of patients (Damiano et al, 2001;Ross and Engsberg, 2007). There is a general agreement that both neural and muscular factors contribute to this weakness (Mockford and Caulton, 2010).…”

Therapeutic effects of electrical stimulation on manual function of children with cerebral palsy: Evaluation of two cases

“…Muscle weakness and alterations in passive stiffness are often present, resulting in important imbalances [2 -5]. Such imbalances can contribute to movement slowness and inefficiency and limit active movement, inhibiting the use of the affected limb in daily life activities and restraining acquisition and development of motor functions [2,3,5].Neuromuscular electrical stimulation (NMES) is used as an adjunct to facilitate and re-educate voluntary movement and to maintain strength and range of movement [6]. In clinical practice, this intervention modality has been used in patients with a variety of neurological dysfunctions, showing positive results in the treatment of peripheral nerve paralysis, cerebrovascular accidents and other conditions.…”