Stroke is a leading cause of disability worldwide. At six months post-stroke patients, 50-70% of patients continue to have upper limb (UL) impairments. The most common problems of the UL are paresis and spasticity leading to residual functional deficits. Higher-order motor control skills such as stability, dexterity and coordination are crucial features of functional movement, that are affected by central nervous system damage. A movement lacking in stability or poorly coordinated is functionally impaired  given the unpredictable environment. Although clinical outcome measures cover the domains described by the International Classification of Functioning, no measures specific assess higher-order motor control skills. Recently, new computational approaches have been described to quantify impairments of movement stability (i.e., synergy index) when  complex multi-joint movements are performed, such as reaching and multi-muscle whole-body tasks. These methods are based on analysis variability, reflecting how joint movements are combined to stabilize a particular task, e.g., endpoint precision. Stability and coordination of movement can be used to track motor recovery following treatment interventions that are aimed at improving the voluntary control of movement in stroke patients. The knowledge of higher-order motor control skills may help to develop new rehabilitation treatment strategies, leading to a better knowledge of recovery processes.

HOW CAN WE MEASURE COORDINATION AND STABILITY IN STROKE PATIENTS?