Proprioceptive Reflexes In Spasticity After Stroke

In this study, total joint dynamics including reflexive impedance was assessed of the hemiparetic upper limb in 7 patients in the chronic phase after stroke using continuous random force perturbations. We found indications for altered reflexes in the paretic limb: 1) evidence for preference of position feedback over velocity feedback indicating possible blocking of la afferent information from the muscle spindles and 2) larger time delays of the reflex loop, indicating dominance of medium latency over short latency reflexes. Negative influences on joint stability and thus on limb functioning after stroke may be caused by qualitative (alteration of reflexive pathways) more than quantitative (reflexes being too high) changes in the reflex loops.