Surface Electromyography of Lumbar Paraspinal Muscles During Seated Passive Tilting of Patients With Lateropulsion Following Stroke

Abstract

Background. Patients with lateropulsion (pushing) following stroke push toward the contralesional side. Their response to a passive tilt while seated has not been studied with surface electromyography (sEMG) of lumbar paraspinal muscles. Objective. To compare onset, response duration, and trends in lumbar paraspinal muscle activity among patients with stroke, patients with stroke and lateropulsion, and healthy controls during seated passive tilting. Method. Seated subjects were passively tilted in the frontal plane at slow and fast speeds. Bilateral sEMG electrodes at the level of lumbar vertebrae 3 recorded paraspinal muscle activity. Surface EMG onset, response duration, and type of muscle activity were compared for 15 patients with stroke and lateropulsion, 12 patients with uncomplicated stroke, and 16 healthy, aged controls. Correlations were assessed between the Burke Lateropulsion Scale (BLS) and both sEMG onset and sEMG response duration. Results. Onset of muscle activity was similar in all groups. Patients with lateropulsion showed decreased sEMG response duration in weak-sided paraspinal muscle activity during slow, passive tilting to the strong side. They had more variable muscle activity during fast, passive tilting to the weak side than controls. BLS scores did not correlate with dependent variables. Conclusions. Patients with lateropulsion activated paraspinal muscles with similar onset time as controls during seated passive tilting. Lateropulsion influences weak-sided paraspinal response duration during passive tilting. Graviceptive neglect may explain some of this difficulty with sustaining contractions, but weakness may also be a contributing factor.