SECTION NEWS & NOTES: President's Perspective
The Neurology Section unveiled its newest Regional Course at the Combined Sections Meeting of the APTA in Chicago this February, titled “Neurologic Practice Essentials: Exploring Neuroplasticity and Its Rehabilitation Implications.” The concept of neuroplasticity has long influenced scientific investigators and therapeutic interventions, yet there are still those who question the relevance of neuroplasticity to physical therapy practice. So this perspective addresses the question “Why is neuroplasticity important to clinicians in neurologic physical therapy practice?”
First, what is neuroplasticity? Simply, it refers to the capacity of the nervous system to change, and this change is not unique to central nervous system (CNS) injury or as a response to rehabilitation protocols. Neurons have the capacity to change their structure and function, according to the inputs generated by activity and learning; in fact, neuronal change is the basis for memory and behavioral change, resulting from experience. Plasticity takes place constantly, whether we are undergoing intense training or doing absolutely nothing. Furthermore, plasticity can be positive (adaptive) or negative (maladaptive).1
After CNS injury, neuroplasticity is the key to functional recovery; it also underlies many aspects of motor dysfunction (spasticity, synergistic movements). Therefore, it is imperative that we, as clinicians, understand the impact of physical therapy on neural reorganization during recovery. Much of neuroscience research over the past 3 decades—and, more recently, neurologic physical therapy research—has focused on understanding the mechanisms of recovery as well as its drivers so that we can maximize the effects of our treatments.
So, what do we know about neuroplasticity, following CNS injury? First, some degree of functional recovery is achieved by neurons adjacent to the damaged area assuming control of lost functions (for example, neurons typically controlling elbow/shoulder function now control hand function).2 Second, some recovery is manifested by increased control from the contralesional hemisphere,3,4 yet better recovery is typically associated with a return to ipsilesional control.5 Not surprisingly, there is much that we don't know about the capacity of the nervous system to change, using silent networks of neurons or other methods of reorganization. However, we do know that in the presence of inactivity, neurons cease functioning and will eventually die,1 so activity is a necessary component of recovery. Still, there is also a need for caution, since intense early activity may actually increase lesion size, with exaggerated functional loss.6
As neurologic physical therapists, this information should be exciting and a bit threatening because it emphasizes that what we do matters; thus, we need to understand that how and what we do has a critical impact on the outcome of CNS injury. Neuroplasticity seems best stimulated by intense repetitious practice that challenges yet doesn't exhaust the nervous system;1,6,7 it is imperative that treatment not just focus on repetition but also challenge the skill level of the client. Conversely, treatment that focuses on compensatory movements, especially the lesser-impaired extremities assuming primary function for more impaired extremities, can lead to neural reorganization that can subsequently impede further recovery by inducing a cascading loss of neurons in the lesioned cortex.1
The outcomes of recent clinical trials emphasize these points. As a group, the SCILT (Spinal Cord Injury Locomotor Trial),8 EXCITe (Extremity Constraint Induced Therapy Evaluation),9 and LEAPS (Locomotor Experience Applied Post-Stroke) trials, to name just a few, highlight the importance of high-intensity and repetitious training in enhancing functional recovery after CNS injury that is superior to typical care provided in today's rehabilitation environment. It will be imperative that we translate the findings of these phase III clinical trials to the current clinical environment through the incorporation of team-based intensity-driven care that includes home-based activities mirroring the repetitious nature of these training protocols, to effectively challenge the nervous system and promote neuroplasticity. This type of impactful clinical change will require a partnering of neurologic physical therapy clinicians and scientists to evaluate the best implementation strategies. It is an exciting time in neurologic physical therapy, and neuroplasticity has to be the focus for all of us.
1. Kleim JA, Jones TA. Principles of experience-dependent neural plasticity: implications for rehabilitation after brain damage. J Speech Lang Hear Res. 2008;51:S225–S239.
2. Nudo RJ, Wise BM, SiFuentes F, Milliken GW. Neural substrates for the effects of rehabilitative training on motor recovery after ischemic infarct. Science. 1996;272(5269):1791–1794.
3. Levy C, Nichols D, Schmalbrook P. Constraint induced movement therapy for chronic stroke upper limb hemiplegia restores function and induces plasticity as seen on functional magnetic resonance imaging. Am J Phys Med Rehabil. 2001;80(1):4–12.
4. Takatsuru Y, Fukumoto D, Yoshitomo M, Nemoto T, Tsukada H, Nabekura J. Neuronal circuit remodeling in the contralateral cortical hemisphere during functional recovery from cerebral infarction. J Neurosci. 2009;29(32):10081–10086.
5. Nair DG, Hutchinson S, Fregni F, Alexander M, Pascual-Leone A, Schlaug G. Imaging correlates of motor recovery from cerebral infarction and their physiological significance in well-recovered patients. Neuroimage. 2007;34:253–263.
6. Kozlowski DA, James DC, Schallert T. Use-dependent exaggeration of neuronal injury after unilateral sensorimotor cortex lesions. J Neurosci. 1996;16(15):4776–4786.
7. Nudo RJ. Functional and structural plasticity in motor cortex: implications for stroke recovery. Phys Med Rehabil Clin N Am. 2003;14:S57–S76.
8. Dobkin B, Barbeau H, Deforge D, et al. Weight-supported treadmill vs over-ground training for walking after acute incomplete SCI. Neurology. 2006;66:484–493.
9. Wolf SL, Winstein CJ, Miller JP, et al. Effect of constraint-induced movement therapy on upper extremity function 3 to 9 months after stroke. JAMA. 2006;206(17):2095–2104.
10. Duncan PW, Sullivan KJ, Behrman AL, et al. Body-weight supported treadmill rehabilitation after stroke. N Engl J Med. 2011;264(21):2026–2038.