Movement velocity effect on cortical reorganization and finger function in stroke.

Abstract

Paralysis of limb movement after stroke is a major cause of disability. Recovery of function is linked to favorable brain reorganization. The brain is primed for neuroplastic reorganization after stroke but the rehabilitation interventions must be well designed. Forced use of the paretic limb as a training regimen has been shown to be effective; however, the optimal kinematic parameters are not known. Studies in primates have shown that motor cortical neurons are coded for velocity of limb movement. Studies in healthy humans have shown a relationship between velocity of limb movement and cortical activation. Thus, we hypothesize that higher-velocity finger movement training will be significantly more effective than lower-velocity and that the improved finger function will correlate significantly with brain reorganization. Multiple data points were collected using single-subject cross over design with functional magnetic resonance imaging (fMRI), transcranial magnetic stimulation (TMS), and function tests. Subjects were trained at home, assisted by telerehabilitation devices supervised by a remote physical therapist. Subjects performed 28,800 repetitions of finger extension and flexion movements at lower-velocity and 28,800 at higher-velocity separated by a 3-week baseline phase. Fast-velocity training had significantly greater functional improvement compared to the slow-velocity training in the Box and Block Test, but not consistently in the Jebsen-Taylor and finger force tests. Fast-velocity training did not show significantly greater cortical reorganization compared to the slow-velocity training by TMS or fMRI testing. Further studies are indicated to conclude the impact of movement velocity on behavioral function and brain reorganization in stroke.