Rhythmic robotic training enhances motor skills of both rhythmic and discrete upper-limb movements after stroke: a longitudinal pilot study

Abstract

Discrete and rhythmic movements are two fundamental motor primitives being, at least partially, controlled by separate neural circuitries. After a stroke, both primitives may be impaired in the upper limb. Currently, intensive functional movement therapy is recommended after stroke, but it is mainly composed of discrete movements. No recommendation is made for the specific training of rhythmic movements. However, if they form two different primitives, both should receive a specific training to recover the complete motor repertoire, as many daily live movements integrate both of them. This paper reports the effects of a pure unilateral rhythmic movement therapy on motor performance, after stroke. Thirteen patients with chronic stroke participated in this longitudinal pilot study. They were assessed twice before the therapy to validate their chronic state, and twice after the last session to establish the short-term and long-term effects of the therapy. The therapy itself was composed of 12 sessions spread over 1 month. The exercises consisted in performing straight or circular rhythmic movements, while receiving assistance as need through a robotic device. Short-term and long-term improvements were observed in rhythmic movements regarding smoothness, velocity, and harmonicity. More surprisingly, some transfer occurred to the untrained discrete movements. This finding disputes previous studies that reported no transfer from rhythmic to discrete movements with healthy participants.