Reduction of common motoneuronal drive on the affected side during walking in hemiplegic stroke patients

The objective of this study was to use motor unit coupling in the time and frequency domains to obtain evidence of changes in motoneuronal drive during walking in subjects with stroke. Paired tibialis anterior (TA) EMG activity was sampled during the swing phase of treadmill walking in eight subjects with unilateral stroke. On the unaffected side, short-term synchronization was evident from the presence of a narrow central peak in cumulant densities and from the presence of significant coherence between these signals in the 10-25Hz band. Such indicators of short-term synchrony were either absent or very small on the affected side. Instead, pronounced 10Hz coupling was observed. It is suggested that reduced corticospinal drive to the spinal motoneurones is responsible for the reduced short-term synchrony and coherence in the 10-25Hz frequency band on the affected side in hemiplegic patients during walking.Significance: This is of importance for understanding the mechanisms responsible for reduced gait ability and development of new strategies for gait restoration.