Biceps brachii and forearm muscle morphology related to forearm and hand deformities in spastic cerebral palsy.

INTRODUCTION: Previous studies have identified morphological alterations in spastic muscles focusing predominantly on gross motor muscles, with specific emphasis on those of the lower limbs. There is minimal information on the morphology of spastic upper limb muscles in relation to clinical deformity. Therefore, the aim of this study was to investigate the morphological parameters of the biceps brachii and forearm muscles according to the severity of forearm and wrist and finger deformities in children and adolescents with spastic cerebral palsy. METHODS: A total of 87 children and adolescents with spastic cerebral palsy were recruited. The Gschwind and Tonkin and Zancolli classification systems were used to grade forearm pronation and wrist and finger deformities, respectively. Morphological parameters, including muscle thickness, anatomical cross-sectional area and pennation angle (PA) were assessed using a B-mode ultrasonographic device. RESULTS: Significant differences in morphological parameters were observed according to the severity of upper limb deformities. Specifically, as the severity of forearm, wrist and finger deformities increased, the muscle thickness and anatomical cross-sectional area of the biceps brachii, pronator teres and flexor carpi radialis significantly decreased. In contrast, the pennation angle of the extensor digitorum increased with the severity of forearm and wrist and finger deformities. CONCLUSION: These findings support the role of spasticity-induced morphological alterations in the development of upper limb contractures and highlight the clinical value of muscle architecture assessment in guiding targeted therapeutic interventions. LEVEL OF EVIDENCE: III.