Core Strength for Head Control and Quality of Life in Cerebral Palsy

The HCS served as the primary outcome measure. It is a 5-point ordinal scale (0 = no control, 4 = complete head control) developed and validated by Thomas et al. (2019) for children with significant motor delay. The scale grades the child's capacity to initiate, maintain, and orient the head against gravity in three standardized positions: supine, prone, and supported sitting.

The SATCo was used as the primary measure of hierarchical trunk control. The instrument evaluates trunk control across seven sequential anatomical segments: head, upper thoracic, mid-thoracic, lower thoracic, upper lumbar, lower lumbar, and full trunk. At each segment, the examiner provides manual stabilization immediately below the segment under test and grades three control domains: static (maintaining posture without external perturbation), active (maintaining posture during voluntary head or upper-limb movement), and reactive (maintaining posture during external perturbation).

The FSA, used here as a clinically pragmatic alternative, grades functional muscle recruitment during structured transitional maneuvers on a 1-5 ordinal scale. Cervical and trunk flexor strength was assessed via the pull-to-sit maneuver, examining the child's ability to actively flex the head and trunk against the examiner's slow upward traction. Cervical and trunk extensor strength was assessed via prone suspension over the therapist's lap, examining the child's ability to extend the head and upper trunk against gravity from a supported prone position.

The Gross Motor Function Measure-66 (GMFM-66) is a criterion-referenced, Rasch-modelled instrument designed to evaluate change in gross motor function in children with cerebral palsy. For children at GMFCS levels IV and V, the Item Set-1 short form, derived from the full 66-item scale to reduce respondent burden while preserving measurement properties for severe phenotypes, was used in this trial. Scores are expressed on a 0-100 interval scale, with higher values indicating greater motor capacity.

The Caregiver Priorities and Child Health Index of Life with Disabilities (CPCHILD) is a parent-completed, condition-specific, multidimensional measure of health-related quality of life developed and validated specifically for children with severe non-ambulant cerebral palsy. The instrument covers six domains-activities of daily living/personal care, positioning/transferring/mobility, comfort and emotions, communication and social interaction, health, and overall quality of life-and yields a transformed total score ranging from 0 to 100, with higher scores reflecting better caregiver-reported function and quality of life.