Motor compensation and its effects on neural reorganization after stroke

• Published in: Nature reviews. Neuroscience Vol. 18; no. 5; pp. 267 - 280
• Main Author: Jones, Theresa A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.05.2017; Nature Publishing Group
• Subjects: 631/378/2591; 631/378/2632; 64/86; 692/699/375/534; 692/700/565/491; Adaptation, Physiological - physiology; Animal Genetics and Genomics; Behavioral Sciences; Biological Techniques; Biomedicine; Brain research; Elbow; Hands; Humans; Motor skills; Nerve Regeneration - physiology; Neural circuitry; Neurobiology; Neuronal Plasticity - physiology; Neurosciences; Observations; Patient outcomes; Physiological aspects; Recovery of Function - physiology; review-article; Stroke; Stroke - physiopathology; Stroke Rehabilitation
• ISSN: 1471-003X; 1471-0048; 1469-3178
• DOI: 10.1038/nrn.2017.26

Key Points The development of compensatory movement strategies is a reliable consequence of strokes that result in motor disabilities. Obvious forms of compensation for upper-limb disability after stroke include dominant reliance on the non-paretic upper limb and the use of trunk movements, in place of distal movements, to control the paretic upper limb. Converging evidence from animal and clinical studies of stroke indicate that reliance on the obvious forms of compensation described above can limit the recovery of more-normal movements and more-functional use of the paretic upper limb. Their potential to do so can be expected to vary with impairment severity. By contrast, the use of relatively subtle compensatory strategies to perform skilled motor tasks with the paretic upper limb can precede the recovery of more-normal movements on those tasks. The initial reliance on compensatory strategies that approximate normal movements may enable the task practice that is needed to support the recovery of those movements. Both the effects of motor rehabilitative training focused on the paretic limb and the development of compensatory movement strategies depend on learning-related neural plasticity mechanisms that can be facilitated by their interaction with early post-stroke neuroregenerative responses. As compensation starts early after stroke, its neural plasticity mechanisms are probably normally facilitated by this interaction. In rodent models of stroke, the neural plasticity involved in learning to compensate with the non-paretic upper limb can compete with the neural plasticity related to rehabilitative training of the paretic forelimb. This competitive plasticity is a putative mechanism by which compensatory strategies counter functional improvements in the paretic upper limb and exacerbate its disuse. Compensation is not currently receiving the prominent attention in animal models of stroke that is warranted by its reliable clinical manifestation and its potential to either promote or impede recovery. A better understanding of the neural mechanisms, and adaptive and maladaptive consequences, of behavioural compensation has a strong potential to lead to new treatments that optimize functional outcome after stroke. Stroke survivors often adapt to the loss of upper-limb function by adopting compensatory strategies. Jones discusses evidence that these compensatory strategies may influence the neural remodelling processes that occur after the initial stroke and can have mixed effects on functional outcome of the paretic limb. Stroke instigates a dynamic process of repair and remodelling of remaining neural circuits, and this process is shaped by behavioural experiences. The onset of motor disability simultaneously creates a powerful incentive to develop new, compensatory ways of performing daily activities. Compensatory movement strategies that are developed in response to motor impairments can be a dominant force in shaping post-stroke neural remodelling responses and can have mixed effects on functional outcome. The possibility of selectively harnessing the effects of compensatory behaviour on neural reorganization is still an insufficiently explored route for optimizing functional outcome after stroke.