We have studied the ratio on max. H/M and max. F/M in 20 hemiplegics respectively over the involved and non-involved arms. Each wave was recorded from abductor digiti minimi, and 16 consecutive stimuli were applied to each side of each subject. In 12 hemiplegics with a disused arm, amplitude H/M ratio was found to be significantly higher on the spastic than on the non-involved side. There proved to be a stastically significant association between amplitude H/M ratio and duration H/M ratio (r=0.75, p<0.05). Amplitude F/M ratio was only slightly higher on the spastic than on the normal side. The results indicate that H/M ratio expressed the proportion of anterior motoneuron pool to be excited better than F/M ratio and that 10 consecutive stimuli were enough to get a methodologic convenience.
The H reflex might play a more important role than the F wave to evaluate as an index of the spastic state.
