Evaluation and treatment of patients with stroke: an emg and h-reflex study

This study consisted of four experiments that investigated the soleus H-reflex and soleus/tibialis anterior muscle pair activation in healthy subjects and patients with cerebrovascular accident (CVA) or stroke. In Experiment 1, the purpose was to establish test-retest reliability of the soleus H-reflex for both groups during gait-simulated postures between two days. Experiment 2 investigated soleus H-reflex amplitudes and soleus/tibialis anterior EMG activation during gait-simulated postures in healthy adults. Experiment 3 compared the two groups average soleus H-reflex amplitudes and related soleus/tibialis anterior EMG recorded in gait-simulated postures. Experiment 4 assessed (using soleus H-reflex and tibialis anterior EMG) the effects of an exercise program intended to improve the patients' motor control at the ankle joint determined by improvements in gait speed. Ten healthy subjects and 9 patients participated in Experiment 1; Experiment 2 included 21 healthy subjects; Experiment 3 included 21 healthy subjects and 9 patients; and 9 patients participated in Experiment 4. Soleus H-reflex amplitudes and soleus/tibialis anterior EMG activity were recorded for both groups in each of five gait-simulating postures (N: freestanding, PO: push-off, HC: heel-contact, SW: swing and MS: mid-stance) for experiments 1-3. Patients participated in a 4-week exercise (3 sessions/week) that consisted of repetitive ankle dorsiflexion of the paretic limb that simulated the swing phase (open chain) of the gait cycle. Pre- and post-training gait speed measures for self-paced and fast-paced gait speed, soleus H-reflex, and soleus/tibialis anterior EMG were recorded. Results of Experiment 1 showed test-retest of the soleus H-reflex was high for each posture in both groups. Experiment 2 showed a relationship between normal gait and gait-simulated postures for soleus H-reflex/EMG activation. The results of Experiment 3 found the patient group exhibited a lack of inhibition of the soleus H-reflex amplitude in postures HC and SW compared to the healthy subjects. In Experiment 4 results, the patient group had a significant improvement for gait speed in the fast-paced gait condition only. Individual comparisons of pre- and post-training results showed that the majority of patients improved in their control of soleus inhibition and tibialis anterior activation.