Evaluation of abnormal synergy patterns poststroke: relationship of the Fugl-Meyer Assessment to hemiparetic locomotion.

BACKGROUND: Assessment of poststroke motor impairment has historically focused on the ability to move within and outside of abnormal synergistic motor patterns and is typically quantified by the Fugl-Meyer Assessment (FMA). However, it is unclear if the voluntary, isolated movement tasks of the FMA are appropriate for evaluating walking task-specific motor control requirements because walking is cyclical and involves considerable sensorimotor integration.
OBJECTIVE: The purpose of this study is to test whether the motor impairment measured by the FMA is indicative of motor dysfunction during walking in poststroke adults.
METHODS: Thirty-four individuals with chronic poststroke hemiparesis and 17 healthy controls walked for 60 seconds on an instrumented treadmill while recording electromyographic activity (EMG) from 8 lower extremity muscles. EMG recordings were also obtained during the FMA for those with hemiparesis to examine muscle activation patterns. Each participant was examined with a battery of walking-specific clinical and biomechanical assessment tools and stratified based on the FMA synergy (FMS) score. To further quantify muscle activation patterns during walking, a nonnegative matrix factorization (NNMF) determined the number of independent modules required to describe 90% of the total variance in the EMG patterns.
RESULTS: Stratification poorly differentiated motor activation across FMA tasks as well as EMG patterns during walking. While FMS correlated with 2 of 6 walking assessments, the number of EMG modules significantly correlated with all 6 walking performance measures.
CONCLUSIONS: Voluntary, discrete activities as performed in the FMA may be inadequate to capture the complex motor behavior in walking. Conversely, walking-specific evaluations such as NNMF appear more appropriate.