Postural stability and functional balance in children with brachial plexus birth injury

Objective To evaluate postural stability and functional balance in children with brachial plexus birth injury (BPBI) and explore potential associations between upper limb involvement and balance performance.Methods This cross-sectional case-control study consisted of 30 children with BPBI and 15 typically developing peers. Upper limb function was evaluated using the Modified Mallet Scale (MMS) and the Assisting Hand Assessment (AHA), and injury severity was classified using the Narakas classification. Objective measures of postural stability and functional balance included the Biodex Balance System (Postural Stability Test, Limits of Stability Test (LoST), and Fall Risk Test (FRT) under eyes-open conditions), the Pediatric Balance Scale (PBS), and the Timed Up and Go (TUG) test. The relationships among age, injury severity, upper limb function, and balance performance were also evaluated.Results Dynamic balance performance differed significantly between children with BPBI and controls, particularly in LoST (total, anterior, right, anterior-right, and anterior-left; all p < .05). There were also significant differences in PBS scores (p = .038) and FRT scores (p = .030). However, the median values between groups were identical, suggesting subtle distributional variations rather than distinct functional impairments. In unadjusted analyses, injury severity was associated with TUG performance (r = 0.459, p = .011). No significant correlations were found between the upper limb functional measures (AHA) and objective balance parameters.Conclusion Children with BPBI have a clinical profile of balance characterized by subtle alterations of dynamic stability and functional weight shifting. In this population, postural control appears to be influenced more by developmental maturation and proximal compensatory strategies than by the extent of distal upper limb involvement.