Deficits in Reciprocal Inhibition of Children With Cerebral Palsy as Revealed by H Reflex Testing

This study was designed to determine whether children with cerebral palsy (CP) showed more co-activity than comparison children in non-prime mover muscles with regard to the prime mover during maximum voluntary isometric contraction (MVIC) of four lower-extremity muscles. Fourteen children with spastic diplegic CP (10 males, four females; age range 4-10y), seven children with spastic hemiplegic CP (five males, two females; age range 5-10y), and 14 comparison children (eight males, six females; age range 4-11y) participated in the study. Gross Motor Function Classification System levels of the children with CP were as follows: eight children at Level I, seven children at Level II, five children at Level III, and one child at Level IV. Surface electromyographic recordings were made simultaneously from the vastus lateralis (VL), medial hamstrings (MH), tibialis anterior, and lateral gastrocnemius (LG) muscles during maximal voluntary contraction. Children with CP showed higher co-activity than the comparison children in both antagonist and adjacent muscles. This was particularly true when VL, MH, or LG muscles were engaged in MVIC. These findings may contribute to the weakness and abnormal movement patterns seen in CP, and they have implications for treatment.Cerebral palsy (CP) is a multisymptomatic, non-progressive disorder caused by an early insult to the developing brain. The motor dysfunction includes features such as retained developmental reactions, spasticity, dyskinesias, secondary musculoskeletal conditions, excessive muscle co-contraction, central dyscoordination, and paresis. 1 Recently, the impact of multiple neurological symptoms and deficits has been acknowledged and a new definition and classification has been presented. 2 The focus of rehabilitation has changed considerably over the past century; in the first half of the century, treatment entailed muscle stretching and strengthening, application of orthoses, and functional skill training. This was abandoned when concern arose that strength training caused undesirable spasticity. Subsequently, assumptions about the relationships between strength and spasticity were refuted. 3 Current renewed attention to strengthening is supported by evidence for positive functional benefits of strength training. [4][5][6] Although several studies point to the presence of weakness in children with CP, 7-9 the mechanism behind this weakness is not fully understood and probably results from multiple factors. 10 Weakness could be caused by an inability to activate agonist muscles voluntarily, 8,11,12 changes in contractile and non-contractile muscle morphology, 13,14 or excessive antagonist muscle co-contraction or co-activation, effectively reducing force or torque-generating capacity. 7,8,11 Analysis of agonist/ antagonist pairs in lower-extremity muscles shows increased co-contraction or co-activity to varying extents in selected muscles in participants with CP compared with those in healthy participants. 7,8,11 A reduced ability to activate intended muscles and in...

Section: Discussionmentioning

confidence: 99%

Co‐activity during maximum voluntary contraction: a study of four lower‐extremity muscles in children with and without cerebral palsy

Tedroff

Knutson

Soderberg

2008

“…Alternating limb movements are particularly difficult for children with CP. 14,16 The challenge is to control Ia inhibitory interneurons which receive direct input from muscle stretch receptors. 22 Inhibition of soleus motoneurons via these pathways comes into play especially when descending steps.…”

Section: Discussionmentioning

confidence: 99%

“…To avoid causing participants stress, possibly affecting supraspinal control, 16 they were not specifically encouraged to make maximum movements.…”

Section: Massagementioning

confidence: 99%

Effects of massage on the mechanical behaviour of muscles in adolescents with spastic diplegia: a pilot study

MacGregor

Campbell

Gladden

et al. 2007

Calf muscles of five adolescents aged 12 to 15 years (three males, two females) with spastic diplegia were massaged for 14 minutes twice a week for 5 weeks in a controlled sequence, stretching the muscles transversely rather than longitudinally, without eliciting pain. Slow, passive test stretches were applied before and after massage. After massage, the range of movement was not consistently increased but, on average, greater force was needed to stretch the muscle than before massage. However, after massage the resting ankle angle sometimes changed so that the calf muscles were either shorter or longer. We suggest that these phenomena could be explained if massage resets sarcomere lengths which corrects for thixotropic effects (i.e. previous use modifies a muscle's mechanical behaviour). A redistribution on sarcomere lengths within muscles could also have reset proprioceptive feedback. The incidence of abnormal stretch reflexes during test stretches fell from 40 to 22%, comparing the first five sessions with the last five sessions. The amplitude of voluntary alternating ankle rotation increased in three participants. Motor skills were assessed with the Gross Motor Function Measure‐66 (GMFM‐66) 1 week before the test period, during the 5th week, and 12 weeks later. Our participants in Gross Motor Function Classification System (GMFCS) Levels I and II made sustained improvements in GMFM‐66 scores (6.4% at 5 weeks falling to 5.5% at 17 weeks), one increase being significant. One participant in GMFCS Level III improved significantly only after massage of all leg muscles for 30 weeks.

“…We suggested that the latter result was either due to a general disturbed motor output (for example, Leonard et al 1990, Neilson et al 1990, or an indistinct internal representation based on disturbed sensory input. However, we were unable to differentiate between these two possibilities based on our data.…”

Section: Bilateral Transfer Of Sensory Informationmentioning

confidence: 98%

Fingertip forces during object manipulation in children with hemiplegic cerebral palsy. II: Bilateral coordination

Gordon

Charles

Duff

1999

The present study examines the coordination of fingertip forces during object manipulation in both the involved and non‐involved hand of 14 children with hemiplegic cerebral palsy (CP) aged between 8 and 14 years. While no impairment could be observed in the non‐involved hand, subtle deficits in the sequencing of the grip–lift movement were observed in all children tested in this hand. However, they were able to scale the fingertip force output of the non‐involved hand in advance (use anticipatory control) based on the object's weight. In the second experiment in this paper, we tested whether the anticipatory control can be generalized across hands. The results indicate that sensory information from the non‐involved hand can be used for anticipatory scaling of isometric force increase during subsequent lifts with the contralateral involved hand. These findings suggest that the initial lack of anticipatory control usually observed in the involved hand of children with hemiplegic CP is likely to be based on disturbed sensory input.