Influence of two different sitting positions on postural adjustments in children with spastic diplegia

The present study addressed the question whether the deviant postural adjus tments in children with spastic diplegia can be attributed to their crouche d sitting position or primarily to their neural deficit. Postural adjustmen ts during sitting in an erect and in a crouched position on a movable platf orm were assessed in 10 children, aged 3 to 7 years 6 months, with mild-to- severe forms of spastic diplegia, and 10 age- and sex-matched control child ren. Multiple surface EMGs of neck, trunk, and leg muscles and kinematics o f head, body sway, and pelvis were recorded during forward and backward tra nslations. The children with normal motor development showed a distinct ada ptation of postural adjustments to sitting position. The children with cere bral palsy (CP) had a deficient adaptational. capacity which was more prono unced in the erect than in the crouched position. Thus, the crouched sittin g position did not induce postural deficiency but seemed to offer a solutio n to the sensory-motor problem of the instability experienced. Children wit h severe diplegia exhibited a lack of direction specificity in the leg musc les during backward body sway, which points to a basic deficit in postural control. In addition, these children showed marked dysfunctions in the prec ise tuning of the postural adjustments to task-specific conditions. In the children with mild-to-moderate forms of CP the basic level of control was i ntact.