Effect of electrical stimulation of hamstrings and L3/4 dermatome on gait in spinal cord injury

Objective. To determine the effect of electrical stimulation of hamstrings and L3/4 dermatome on the swing phase of gait. Materials and Methods. Five subjects with incomplete spinal cord injury (SCI) with spasticity were included. Two electrical stimulation methods were investigated, i.e., hamstrings and L3/4 dermatome stimulation. Both interventions were applied during the swing phase of gait. The main outcome measures were step length, maximum hip, and knee flexion during the swing phase of gait. In three subjects changes of spinal inhibition during gait were evaluated using the Hoffman reflex/m (motor)-wave (H/M) ratio at mid swing. Results. The hip flexion decreased 4.6 degrees (p < 0.05) when the hamstrings were stimulated during the swing phase, whereas the knee flexion was not changed. The step length did not change significantly. One subject showed a decrease of the H/M ratio to a nonpathologic level during hamstrings stimulation. Conclusion. It was concluded that hamstrings stimulation during the swing phase results in a reduction of the hip flexion in all five SCI subjects. The H/M ratio of the vastus lateralis was normalized using hamstrings stimulation in one of three subjects. Stimulation of the L3/4 dermatome provides no significant changes in gait performance, but in one subject the H/M ratio increased.