Comparison of Electric Stimulation Methods for Reduction of Triceps Surae Spasticity in Spinal Cord Injury

Abstract

van der Salm A, Veltink PH, IJzerman MJ, Groothuis-Oudshoorn KC, Nene AV, Hermens HJ. Comparison of electric stimulation methods for reduction of triceps surae spasticity in spinal cord injury. Objectives To compare the effect of 3 methods of electric stimulation to reduce spasticity of the triceps surae in patients with complete spinal cord injury (SCI) and to investigate the carryover effect. Design Placebo-controlled study with repeated measurements after the interventions. Setting Research department affiliated with a rehabilitation hospital in the Netherlands. Participants Ten patients with a complete SCI were recruited from the outpatient population of the rehabilitation hospital. All subjects had American Spinal Injury Association grade A impairment scores, except for one, who had grade C. The patients had no voluntary triceps surae contractibility. Interventions Forty-five minutes of cyclic electric stimulation of the agonist, antagonist, or dermatome of the triceps surae or a placebo approach. Main Outcome Measures Outcome measures were the Modified Ashworth Scale (MAS), clonus score, and the H-reflex and M wave (H/M) ratio. The electromyographic response to a stretch of the soleus over the whole range of motion was also determined. The magnitude and ankle angle at which the electromyographic response started were calculated. Results Stimulation of the agonist provided a significant reduction in the MAS compared with the placebo approach ( P<.001). There was no significant change in the H/M ratio or the electromyographic response amplitude after any of the stimulation methods, whereas stimulation of the antagonist muscle resulted in a significant reduction in the ankle angle at which the electromyographic response started, compared with the placebo approach ( P<.037). Conclusions Triceps surae stimulation reduces the MAS for that specific muscle, whereas the angle at which the reflex starts changes after antagonist stimulation.