Causal factors affecting gross motor function in children diagnosed with cerebral palsy
Bruce A MacWilliams1,2, Sarada Prasad1, Amy L Shuckra1
1Shriners Hospitals for Children, Salt Lake City, Utah, United States of America.
Insights
Selective voluntary motor control and dynamic motor control significantly impact gross motor function in children with cerebral palsy (CP). Understanding these causal effects helps tailor treatments for better outcomes.
Area of Science:
- Neurology
- Pediatrics
- Rehabilitation Medicine
Background:
- Cerebral palsy (CP) is a complex neuromuscular condition impacting gross motor function.
- Children with CP often present with spasticity, weakness, and motor control deficits.
- The precise causal influence of these impairments on motor function remains unclear.
Purpose of the Study:
- To propose and utilize a causal model to estimate the effects of common impairments on gross motor function in children with spastic CP.
- To measure motor function using the 66-item Gross Motor Function Measure (GMFM-66).
- To compare direct and total effect sizes with bivariate estimates.
Main Methods:
- Retrospective evaluation of 300 consecutive subjects with spastic cerebral palsy.
- Utilized data from routine clinical gait analysis.
- Employed linear regression based on minimally sufficient adjustment sets to estimate causal effects.
Main Results:
- Selective voluntary motor control and dynamic motor control exhibited the largest causal effect sizes on gross motor function.
- Strength and gait deviations showed moderate effects, while spasticity and orthopedic deformity had smaller impacts.
- Bivariate models overestimated the effects of spasticity, strength, and orthopedic deformity compared to causal models.
Conclusions:
- Causal modeling provides a more accurate understanding of impairment effects on gross motor function in CP.
- Identifying key causal factors like motor control allows for targeted therapeutic interventions.
- This knowledge aids clinicians in setting realistic patient expectations and optimizing treatment strategies.
Background:
Cerebral palsy (CP) is a complex neuromuscular condition that may negatively influence gross motor function. Children diagnosed with CP often exhibit spasticity, weakness, reduced motor control, contracture, and bony malalignment. Despite many previous association studies, the causal impact of these impairments on motor function is unknown.
Aim:
In this study, we proposed a causal model which estimated the effects of common impairments on motor function in children with spastic CP as measured by the 66-item Gross Motor Function Measure (GMFM-66). We estimated both direct and total effect sizes of all included variables using linear regression based on covariate adjustment sets implied by the minimally sufficient adjustment sets. In addition, we estimated bivariate effect sizes of all measures for comparison.
Method:
We retrospectively evaluated 300 consecutive subjects with spastic cerebral palsy who underwent routine clinical gait analysis. Model data included standard information collected during this analysis.
Results:
The largest causal effect sizes, as measured by standardized regression coefficients, were found for selective voluntary motor control and dynamic motor control, followed by strength, then gait deviations. In contrast, common treatment targets, such as spasticity and orthopedic deformity, had relatively small effects. Effect sizes estimated from bivariate models, which cannot appropriately adjust for other causal factors, substantially overestimated the total effect of spasticity, strength, and orthopedic deformity.
Interpretation:
Understanding the effects of impairments on gross motor function will allow clinicians to direct treatments at those impairments with the greatest potential to influence gross motor function and provide realistic expectations of the anticipated changes.
