Electrical stimulation driving functional improvements and cortical changes in subjects with stroke

Abstract

It has been proposed that somatosensory stimulation in the form of electromyographically triggered neuromuscular electrical stimulation (NMES) 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, we studied the effects of intensive (60 h/3 weeks) treatment at home with NMES compared with a sham treatment, applied to the extensor muscles of the hemiplegic forearm to facilitate hand opening in 16 chronic stroke subjects. We investigated improvement in functional use of the hand and change in cortical activation as measured by functional magnetic resonance imaging (fMRI). Following treatment, subjects improved on measures of grasp and release of objects (Box and Block Test and 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 and How Well 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, grasp and release (Box and Block [JTHFT]: page turning), and self-rated MAL: Amount of Use score and How Well score. Using fMRI and a finger-tracking task, an index of cortical intensity in the ipsilateral somatosensory cortex increased significantly from pre-test to post-test following treatment. Cortical activation, as measured by voxel count, did not change. These findings suggest that NMES may have an important role in stimulating cortical sensory areas allowing for improved motor function.

Efeitos da estimulação elétrica funcional nos músculos do punho e dedos em indivíduos hemiparéticos: uma revisão sistemática da literatura

“…Cauraugh et al 17 , using the same test, reported a gain of 129% in the FES group, significantly higher than the control group. Kimberley et al 18 found a significant gain in the performance of the Box and Block Test and in subtests of the Jebsen Taylor Hand Function Test only for the FES group. according to the quality of the results of the reviewed articles, there is moderate evidence of the effects of FES on manual dexterity.…”

“…Four studies 7,[17][18][19] had a sample with chronic stroke diagnosis, with post-lesion peri- ods varying from 1 17 to 4 ½ years 18 . Sample size varied from 9 11 to 48 10 subjects divided between treatment and control groups.…”

“…Intervention duration varied from 1 7 to 120 sessions 10 , with half of the articles having an intervention period of 10 to 15 sessions 4,15,18,19 . FES application frequency varied from 1 4,15 to 3 16 times a day, from 2 20 to 5 4,9-11 times a week.…”

“…FES application frequency varied from 1 4,15 to 3 16 times a day, from 2 20 to 5 4,9-11 times a week. Session duration varied from 10 minutes 7 to 6 hours 18 . Current parameters varied, with frequency ranging from 20 to 100 hz 11 , amplitude from 14 17 to 60 ma 9 and pulse width from 200 to 300µs 9,10 .…”

“…Current parameters varied, with frequency ranging from 20 to 100 hz 11 , amplitude from 14 17 to 60 ma 9 and pulse width from 200 to 300µs 9,10 . In most studies, FES was applied to extensor muscles [9][10][11][17][18][19] ; in one study it was applied to wrist and finger flexors 7 and in another, to both muscle groups 4 .…”