Augmented activity of the forearm extensor muscles induced by vibratory stimulation of the palm of the hand in individuals with subacute post-stroke hemiplegia

Abstract

ABSTRACT Primary Objective To examine whether vibration to the palm of the hand induces motor activity in the forearm muscles of individuals with post-stroke and healthy young adults. We hypothesized that the vibration would induce antagonistic muscle activities via the motor cortex. Research Design Observational study using the between- and within-subjects mixed design. Methods and Procedures Vibratory stimulation was applied to the palm of the paretic and non-paretic hands in seven post-stroke hemiplegia, and of the right hand in 22 healthy young adults in the eyes-closed and eyes-open conditions. Surface electromyography (sEMG) was recorded from the forearm extensors and flexors and the sEMG amplitudes were analyzed. Main Outcomes and Results The extensor activities were significantly larger than that of the flexors in all hands. Especially, the extensor activities were augmented when the eyes were open in the paretic and non-paretic hands. Moreover, there was greater muscle activity in the non-paretic hand compared with the paretic hand. Conclusions These novel findings revealed that vibration to the palm augmented the activity of the antagonistic forearm extensors, especially in the paretic hand, which was induced via top-down cortical modulation. Thus, it can be utilized to improve the impaired forearm extensors in post-stroke rehabilitation.