Abstract
Therapeutic effects of transcutaneous electrical stimulation (TES), such as reduction of spasticity and improvements in motor control, have often been observed. The purpose of this study is to evaluate the efficacy of TES on paretic lower extremities of hemiplegic patients from the viewpoint of gait speed, voluntary movement in paretic lower extremity, flexor reflex, and reciprocal Ia inhibition. The tibialis anterior muscle on the paretic side was stimulated by surface electrodes. The frequency of impulses was 30Hz and the pulse width 0.2msec. The intensity of stimulation was adjusted to a level over the threshold for a visible muscle contraction. TES was applied for 20 minutes, with cycles of five seconds of stimulation and five seconds of rest. After TES, the pace of walking among patients quickened and the speed of the voluntary knee extension increased when conducting paretic knee bends. At the same time, the surface EMG showed a reduction in co-contraction and change to reciprocated movements of quadriceps and hamstrings. These findings suggest improvements in voluntary movements of knee joints, though TES was applied on paretic lower leg. Electrophysiologically, the latency of the second component of flexor reflex was prolonged after TES and this change did not occur after only resting without applying TES. Reciprocal Ia inhibition, which was tested by recording H-reflex responses in the calf muscles, was not observed in paretic lower extremity of hemiplegic patients. But the mean amplitude of H-reflex responses of calf muscles was lowered after TES. These findings suggest that TES could lead to improved voluntary movements effecting directly not only at the spinal segmental level but also indirectly at the supra spinal level. TES may also inhibit alpha motoneurones by controlling premotoneuronal interneurone pool.
