It appears we are just at the cusp of envisioning what may be possible in the not too distant future with respect to stimulating neural recovery in cerebral palsy. The previous therapy paradigm was to encourage maximal motor performance given the fixed constraints of the primary neurological injury. In the 1990s, the importance of minimizing secondary consequences of the activity limitation imposed by the brain injury, especially from a proactive (preventive) rather than a reactive standpoint, came to the fore-front. The increased use of strength training in cerebral palsy is one outcome of this new emphasis.
The primary injury is no longer thought to be immutable and some neural and behavioral recovery is now considered possible in cerebral palsy. Cortical reorganization in response to training paradigms has now been shown to be possible in those with brain injuries, with these changes coincident with functional gains. Recent advances in neuroscience have highlighted the importance of motor activity for the establishment and reinforcement of neural pathways,27
with the converse occurring when activity is reduced.28
In this decade, much research has been published that highlights the neural effects of different types of motor training or exercise. For example, it has been shown motor skill training increases corticospinal excitability, whereas strength training does not.29
Important differences have also been found in “forced” versus voluntary exercise with the amount of work being equal.30
Activity may be even more critical for those with motor disabilities and has implications for all aspects of their development.31
Clearly, far more work needs to be and is being done to determine the specific effects of different exercise types and doses and how these can be combined with pharmaceutical or other (eg, stem cell–based) approaches to optimize recovery or restoration of function.
The remarkable plasticity of the neuromuscular system is a double-edged sword in cerebral palsy. Muscles and neural pathways are constantly changing in response to motor activity, with the potential for both positive and negative changes, which are far greater at a younger age.32
This provokes a sense of urgency to not only determine the optimal strategies to promote adaptive changes but also to ensure that we are not allowing maladaptive changes to occur through lack of adequate intervention or delaying intervention. As pathways are “pruned” throughout the course of early development, the potential for a more complete recovery may diminish, so timing is likely to be a critical factor.
We now know that specific types of training or maternal and/or cultural handling practices can alter the rate of motor development. For example, the results from a randomized controlled trial of in-home treadmill training for infants with Down syndrome demonstrated accelerated walking acquisition by 4 months compared with controls. 33
Similarly, the new recommendation to place babies in supine rather than prone for sleeping is delaying motor development in infants due to less practice in trunk and proximal joint extension.34
Far earlier identification of children at high risk for developing cerebral palsy is now possible through the use of tests such as the Test of Infant Motor Performance35
or the evaluation of General Movements, 36
so intervention can be initiated earlier. What is not yet known is which types of movements or motor tasks should be encouraged and when, and whether external devices are needed to encourage or augment these. In children with cerebral palsy, the hallmark of which is a deficit in motor control, the challenge is not merely to accelerate motor task acquisition but to enrich the repertoire and coordination of the movements involved in that task. As a note of caution, overstimulation of infant behaviors may be counterproductive or even harmful, so any novel approach must be rigorously evaluated before clinical implementation.