Etiology of impaired selective motor control: emerging evidence and its implications for research and treatment in cerebral palsy.

Selective motor control (SMC) impairment involves movement patterns dominated by flexor or extensor synergies that interfere with functional movements in children with cerebral palsy (CP). Emerging evidence on neural correlates of impaired SMC has important implications for etiology and for the treatment for children with CP. Early evidence on the microstructure of brain white matter assessed with diffusion tensor imaging in adult patients after stroke suggests that the rubrospinal tract may compensate for injury to the corticospinal tract. Furthermore, the observed changes on diffusion tensor imaging corresponded to the degree of SMC impairment. The rubrospinal tract may provide imperfect compensation in response to corticospinal tract injury, resulting in diminished SMC. Cortical mapping evidence in stroke patients indicates that loss of SMC is also associated with increased overlap of joint representation in the sensorimotor cortices. The severity of SMC impairment can be assessed with the recently developed Selective Control Assessment of the Lower Extremity, a validated observation-based measure designed for children with spastic CP. Recent advances in neuroimaging and assessment of SMC provide an opportunity to better understand the etiology and impact of impaired SMC, which may ultimately guide strategic treatment for children with CP.