The effects of electrical nerve stimulation of the lower extremity on H-reflex and F-wave parameters

The main purpose of this study was to investigate the effects of electrical nerve stimulation on alpha motoneurons excitability. The electrophysiological parameters of H-reflex and F-wave were assessed for this object. These experiments was performed on ten non-athletic healthy men without neurologic disorders with mean age 25.6 years (SD 4.4) and three spastic hemiplegic patients with mean age 65.33 years (SD 6.32). In the experimental protocol, electrical stimulation (TENS) applied on common peroneal nerve with frequency 99 Hz and duration 0.25 ms for 30 minutes. H-reflex and F-wave of the soleus muscle were recorded in three stages sequenced immediately, 5 minutes and 10 minutes later on. The parameters such as amplitudes and latencies of H-reflex and F-wave were compared with the data of first record before stimulation. Finally, after 30 minutes application of TENS the following results were obtained: 1. The mean peak to peak amplitude of H-reflexes and F-waves were significantly decreased after application of TENS in normal subjects. (P < 0.05) 2. H/M ratios and F/M ratios were significantly decreased after application of TENS in normal subjects. (P < 0.05) 3. The mean latency of H-reflexes and F-waves were significantly increased after application of TENS in normal subjects. (P < 0.05) 4. In spastic patients, the mean peak to peak amplitude of H-reflexes and F-waves, H/M and F/M ratios were significantly decreased and the mean latencies of H-reflexes and F-waves were significantly increased after application of TENS. The reduction of amplitude of H-reflexes and F-waves, H/M and F/M ratios demonstrated reduction of spasticity in patients group. The above-mentioned parameters are parts of electrophysiological indicators about assessment of spasticity.