Electromyographic and positional changes in the elbows of spastic hemiparetic patients during walking

The displacement of the paretic elbow of hemiparetic patients into flexion during walking is an acknowledged associated reaction characteristic of upper limb spasticity. The main purpose of this study was to examine the step-dependent pattern and magnitude of the angular and electromyographic changes which take place during this flexion movement. Steps-related changes in elbow angle were measured on the paretic side of 14 hemiparetic patients during walking with a 4-point cane. The EMG activity of the ipsilateral biceps and triceps brachii muscles was concomitantly recorded. The activity of the brachioradialis muscle in 8 patients was monitored as well. In another trial, the angular and electromyographic activities were measured bilaterally in 7 patients during free walking. Flexion movement on the paretic side was characterized by a steep increase in flexion occurring during the first 4 steps, followed by a more gradual rise with successive stepping. Neither the electromyographic activity of the elbow flexor nor that of the extensor muscles was related to that flexion movement. The excursion into flexion on the non-paretic side was smaller than on the paretic side and incorporated flexion-extension fluctuations. The associated reaction at the paretic elbow during walking is a postural response which is triggered by the balance perturbation in the gait activity. It starts with a steep rise in flexion which seems to be reflexive in nature. The preservation of elbow flexion during walking may be an expression of stiffening of the elbow flexor muscles fibers.