INTRODUCTION and AIM: The aim of this study was to conduct kinematic analyses of sequential upper-limb movements in order to isolate different kinematic parameters that might explain the sensory-motor-functional deficits and delays commonly observed in children born preterm (PT). Quantitative analyses of reaching movements in PT infants [1] have revealed some promising results in characterizing the influence of a premature birth on movement control. Also, recent findings from studies using kinematic measurements on children with mild and moderate hemiplegic cerebral palsy [2, 3] show that kinematic measurements are valuable for making distinctions between even minor movement coordination problems and for identification of sensory-motor impairments. Nevertheless, there is still limited knowledge of how a preterm birth may effect long-term neuromotor development and few have investigated such effects by means of kinematics.
PATIENTS/MATERIALS and METHODS: This kinematic study is part of a more comprehensive, longitudinal project with the goal of exploring the relationship between brain development/deviation and sensory-motor performance in children born PT. Participants consist of 148 children aged between 4–8 years; sixty-eight PT (<35 weeks’ gestation age (GA), range, 22-35, M = 31.7, SD = 3.4; 30 girls) with no diagnosed impairments, and eighty age matched children born full-term (FT) without medical problems (M age at testing = 6.7, SD = 1.8; 36 girls). The children performed goal-directed unimanual upper-limb task with respective hand, where small beads were picked by use of pincer-grip and threaded onto a rod sequentially. The children were informed to pick and thread as many beads as possible, one bead at the time, during a pre-set recording time of 30 seconds. The upper-limb movements were recorded by a six camera optoelectronic system (ProReflex, Qualisys Inc., Gothenburg, Sweden). The 3D data (extracted from head-, shoulder-, elbow- and wrist-markers) were further analysed by use of customized MATLAB scripts. To analyse possible effect of GA the PT children were divided into two sub-groups: moderately preterm (M-PT) = GA 33-35, n = 35 and very preterm (V-PT) = GA <32+6, n = 30.
RESULTS: The kinematic outcomes analysed by MANOVAs, with side (preferred/ non-preferred) and group (FT, M-PT and V-PT) as categorical predictors, indicating significant group differences in most of the kinematic parameters investigated (e.g., movement duration, 3D distance and segmentation). Differences were mainly evident in the group classified as V-PT compared with M-PT and FT children. Significant correlations between children’s testing age and their kinematic outcomes were also shown within all groups (FT, M-PT and V-PT). These relations were characterized by decreased movement duration, 3D distance and movement segmentation with age.
DISCUSSION and CONCLUSIONS: Investigating kinematic outcome parameters of upper-limb goal-directed movements confirms that a PT birth, especially a very PT birth, seems to have a long-term effect on children’s motor functions. In the present study, this was shown by means of less proficient spatiotemporal organization during sequentially performed goal-directed movements in the children born PT in comparison to the FT children. In conclusion, the kinematic movement registrations/analysis offers a reliable, non-invasive method to detect even subtle neuromotor developmental delay and/or abnormality. Thus, the method provides a unique possibility to investigate a number of crucial issues in relation to cerebral abnormalities and sensory-motor development in at-risk children.
REFERENCES
[1] Fallang, B., Saugstad, O. D., Grogaard, J., & Hadders-Algra, M. (2003). Kinematic quality of reaching movements in preterm infants. Pediatric Research, 53, 836-842.
[2] Domellöf, E., Rösblad, B., & Rönnqvist, L. (2009). Impairment severity selectively affects the control of proximal and distal components of reaching movements in children with hemiplegic cerebral palsy. Developmental Medicine & Child Neurology, 51, 807-816.
[3] Rönnqvist, L., & Rösblad, B. (2007). Kinematic analysis on unimanual reaching and grasping movements in children with hemiplegic cerebral palsy. Clinical Biomechanics, 22, 165-175.