| Others have proposed that somatosensory stimulation in the form of electromyographically-triggered electrical stimulation (EMG-ES) to the peripheral nerve can influence functional measures of motor performance in subjects with stroke and can additionally produce changes in cortical excitability. Using a controlled, double-blind design, I studied the effects of intensive (60 hours/3 weeks) home treatment with EMG-ES vs. sham, to the extensor muscles of the hemiplegic forearm to facilitate hand opening in 16 chronic stroke subjects. I investigated improvement in functional hand use and cortical activation change as measured by functional magnetic resonance imaging (MM). Following treatment, subjects improved on measures of grasp and release of objects (Box and Block Test, Jebsen Taylor Hand Function Test (JTHFT): small objects, stacking, heavy cans), isometric finger extension strength, and self-rated Motor Activity Log (MAL): Amount of Use score. The sham subjects did not improve on any grasp and release measure or self-rated scale, but did improve on isometric finger extension strength. Importantly, however, following crossover, these subjects improved further in the measure of strength, in measures of grasp and release (Box and Block, page turning), and self-rated MAL: Amount of Use score and How Well score. Additionally, using fMRI and a finger tracking task, I found that cortical intensity index in the contralateral sensorimotor cortex increased significantly from pretest to posttest following treatment. Cortical activation, as measured by voxel count did not change. These findings suggest that EMG-ES may have an important role in stimulating cortical motor areas allowing for improved motor function, but that perhaps 'active engagement' is required for cortical reorganization. |
