Disease‐specific body composition patterns in children with cerebral palsy and spinal muscular atrophy

Objectives Spinal muscular atrophy (SMA) and cerebral palsy (CP) are severe neurological conditions characterized by neurodegeneration and non‐progressive brain injury, respectively, both profoundly affecting the nutritional status in children. This observational study aimed to comprehensively assess and compare anthropometry and body composition across groups of children with SMA, CP, and healthy controls (HCs). Methods We enrolled three age‐ and sex‐matched groups of 40 children each: CP (Gross Motor Function Classification System IV–V), SMA (Types I–II), and HC. Anthropometry, skinfolds, and circumferences were collected, and relative z ‐score was calculated. Body fat percentage (BF%) was estimated using the Slaughter equation; fat mass index (FMI), fat‐free mass (FFM), and FFM Index (FFMI) were calculated. One‐way analysis of variance (ANOVA) and robust linear regression were performed adjusting for sex, age, body mass index z ‐score (BMIz), epilepsy, feeding via, ventilation, and pharmacological treatment. Results BMIz was significantly lower in children with neurological impairment than in HC, with no difference between CP and SMA (HC: 0.04 [−0.5; 0.6]; CP: −1.8 [−4.3; −0.6]; SMA: −3.0 [−4.7; −1.2], p < 0.0001). After adjustments, SMA group showed 17.02% higher BF% (95% confidence interval [CI]: 8.27–25.78; p = 0.0003) and higher FMI (+1.37; 95% CI: 0.98–3.75; p = 0.001), compared to CP. When referenced to HC, FMI was higher in SMA and lower in CP. Lastly, SMA showed lower FFMI compared to both CP and HC. Conclusions SMA is characterized by higher BF% and a marked deficit in FFM compared to CP, independently of BMIz, epilepsy, feeding via, and pharmacological treatment. Neurological impairments are associated with distinct body composition patterns, highlighting the need for personalized nutritional assessment.