Unilateral cerebral palsy as a heterogeneous bilateral sensorimotor phenotype

This is the authors' abstract. We don't add key points for this paper.

Background : Unilateral cerebral palsy (UCP) is defined by asymmetric motor impairment, yet the clinically less-affected hand may not develop typically. This review examined evidence for a bilateral sensorimotor phenotype and its implications for assessment and rehabilitation. Methods : PubMed/MEDLINE, Scopus, and Web of Science were searched from inception to June 4, 2026, with additional reference-list screening. We included pediatric studies and selected directly relevant mixed-age mechanistic studies that assessed either hand, bimanual function, bilateral neurobiology, or upper-limb rehabilitation. Study design, sample, outcomes, and limitations were charted and synthesized thematically. Results : Sixty-seven publications informed the core synthesis; two additional papers provided methodological and quality-of-life context. Timed dexterity, complex reaching, and visuomotor tasks most consistently identified less-affected-hand differences. Strength, anticipatory force scaling, proprioception, and motor planning were preserved in some cohorts or varied by task. Bilateral structural injury, corticospinal organization, callosal integrity, mirror movements, synkinesis, and dystonia contributed to heterogeneity without providing a single explanation. Bimanual performance reflected both hand capacities and interlimb coordination: the less-affected hand could slow to synchronize, carry more of the task, or show interference. Rehabilitation studies support intensive upper-limb practice, but do not establish that every less-affected hand requires direct treatment or that one neural phenotype should determine therapy. Conclusions : UCP can present as a heterogeneous bilateral sensorimotor phenotype while remaining markedly asymmetric. Clinicians should compare both hands with age- and dominance-referenced norms and combine unimanual testing with a validated bimanual measure. Prospective studies should test whether bilateral phenotypes improve treatment selection and everyday outcomes.