Aquatic Therapy for a 13‐Year‐Old With Severe Central Hypotonia and Motor Impairment Following Post‐Transplant Encephalopathy: A Hypothesis‐Generating Single‐Case Study

Background Children with severe motor impairments often face significant limitations in physical activity due to high response effort and impaired thermoregulation, leading to secondary physiological decline. Objective This hypothesis‐generating single‐case study evaluated the metabolic and body composition trends associated with an environmental optimization model—utilizing buoyancy and thermoneutral water (36°C)—in a 13‐year‐old with a spastic‐dyskinetic cerebral palsy phenotype secondary to post‐transplant encephalopathy. Methods An A–B–A′ single‐case design was employed. Phase A (baseline) consisted of standard land‐based therapy, followed by Phase B (intervention), which included 40‐min aquatic sessions twice monthly for 6 weeks. Phase A′ (withdrawal) monitored the maintenance of any observed changes. Skeletal muscle mass (SMM) and basal metabolic rate (BMR) were measured bi‐weekly using bioelectrical impedance analysis (BIA). Results Visual analysis using the two‐standard deviation (2SD) band method showed that during the intervention phase, SMM and BMR values exceeded the 2SD threshold. These positive shifts were maintained during the withdrawal phase. Segmental analysis indicated that SMM increases were localized to the trunk and lower limbs, rather than a generalized growth‐related increase. Conclusion Aquatic intervention was associated with positive trends in metabolic proxy indicators. These findings suggest that for medically complex children with limited physiological reserve, optimizing the therapeutic environment—by reducing response effort and ensuring thermoneutrality—may provide a critical window for enhancing motor engagement and metabolic health.