The overall goal of this research is to understand the mechanisms underlying the development of postural control in sitting using new methodology, in order to provide a scientific basis for evaluation and treatment of posture and movement disorders in infants with cerebral palsy. The development of early posture control remains poorly understood despite considerable therapeutic effort. Infants with cerebral palsy show their first delays in the acquisition of sitting, with subsequent problems developing adequate posture and movement control. Identifying the delay, determining the nature of the problem, and evaluating the effectiveness of treatment quickly, are vital in the early part of an infant's life, since this is the time of greatest plasticity. Tools from nonlinear dynamics, which are increasingly being used to examine other biological rhythms, are used in this study to analyze postural sway from center of pressure data during the development of sitting postural control.

Background: The ability to sit independently is fundamental for function but delayed in infants with cerebral palsy (CP). Studies of intervention directed specifically toward sitting in infants with CP have not been reported. Objective: Our purpose was to compare two interventions for improving sitting postural control in infants with CP. Design: For this randomized longitudinal study, infants under 2 years old and at risk for CP were recruited for intervention directed toward sitting independence. Setting: The intervention was conducted at home or at an outpatient facility. Patients: Fifteen typically developing infants (5 months old, SD .5 months at entry) were followed longitudinally as a comparison for postural variables. Thirty-five infants with delays in achieving sitting were recruited. Infants with delays were randomly assigned to a home program (1x/week for 8 weeks; mean age=15.5 months, SD=7 months), or a perceptual-motor intervention (2x/week for 8 weeks; mean age=14.3 months, SD=3 months). Measurements: The primary outcome measure was Center of Pressure (COP) data, from which linear and nonlinear variables were extracted. The Gross Motor Function Measure (GMFM) sitting subsection was our clinical outcome measure. Results: There was a main effect of time in the GMFM sitting subscale and in two of the COP variables. Interaction of group by time factors indicated significant differences between intervention groups on two COP measures, in favor of the group with perceptual-motor intervention. Limitations: The small number of infants limits the ability to generalize the findings. Conclusions: Although both groups made progress in the GMFM, the COP measures indicated an advantage for the group with perceptual-motor intervention. The COP measures appear sensitive for assessment of infant posture control and quantifying intervention response.

Inclusion Criteria:

• able to prop sit for 10 seconds
• 1.5 SD below mean on Peabody motor assessment
• between 5 months and 24 months old
• diagnosis of CP or at risk for CP

Exclusion Criteria:

• blindness
• dislocated hip