Changes in propriospinally mediated excitation of upper limb motoneurons in stroke patients

It has been argued that, in humans, a part of the des-cending command to upper limb motoneurons is trans-mitted through cervical propriospinal premotoneurons. We explored whether excitation of these putative pro-priospinal neurons projecting onto extensor carpi radia-lis (ECR) motoneurons was modi®ed in patients recovering from stroke. Suppression of the voluntary on-going ECR EMG activity by stimulation of cuta-neous afferents in the super®cial radial nerve was used to estimate the component of the descending command passing through the propriospinal relay. The degree of suppression was assessed on both sides of 30 stroke patients (divided into two groups, whether recovery of wrist extension was poor or good by the time of the investigation) and of 34 age-matched controls. Singl