Effects of practice combined with somatosensory or motor stimulation on hand function in persons with spinal cord injury

Abstract

Background: Individuals with chronic tetraplegia prioritize recovery of hand function as an important factor in improving their quality of life. Interventions that may improve hand function and increase corticomotor excitability are functional electrical stimulation (FES), somatosensory stimulation (SS), and task-oriented training.

Objective: We compared functional and corticomotor outcomes in a control condition to changes associated with FES (triggered via electromygraphic signals) and with SS (constant trains), each combined with either unimanual or bimanual training.

Methods: Using a randomized, clinical trial design, comparisons were made to a delayed intervention control group. Participants (n = 24) had chronic tetraplegia, with the ability to activate thenar muscles, and were randomly assigned to either the immediate intervention (intervention) or control/ delayed intervention groups. Primary analyses compared intervention (FES or SS) to control/delayed intervention. Secondary analyses compared subgroups of FES versus SS (regardless of uni- or bilateral training) and uni- versus bimanual training (regardless of stimulation type). Outcomes were assessed before and after the control and the intervention period.

Results: Compared to control/delayed intervention, the intervention group had greater changes in unimanual function and corticomotor area, regardless of whether practice was combined with FES or with SS. Irrespective of stimulation type, the bimanual subgroups improved to a greater extent than the unimanual subgroups on the bimanual hand function test.

Conclusions: Hand training combined with either SS or FES was associated with improved hand use and corticomotor activity in persons with chronic tetraplegia. Both interventions appear to be equally effective.

Keywords: functional electrical stimulation; hand function; neuroplasticity; somatosensory stimulation; spinal cord injury; tetraplegia.

Figures

Figure 1.. Flow chart of participant group assignment. Twenty-four participants were recruited for the study with 9 to 11 individuals in each intervention group, as well as the delayed intervention control group. FES = functional electrical stimulation; SS = somatosensory stimulation.

Figure 2.. Example of cortical map at pre- (top) and postintervention testing (bottom). The numbers and letters are a coordinate system correlating to the grid on the cap. The bars indicate mean amplitude of 3 motor evoked potentials (MEPs).