Objective: To determine the differences of the tendon reflex responses (TRR) between medial and lateral heads of gastrocnemius muscles in healthy subject and spastic patients.
Method: The TRR of medial and lateral heads were evaluated in 20 healthy subjects and 20 spastic hemiplegic patients. From 5 repeated trials on each subject, the shortest latency and duration, and the largest peak-to-peak amplitude of TRR were chosen for the representative value.
Results: 1. The evoked potentials by tendon reflex in medial head of gastrocnemius demonstrated significantly higher amplitude than in the lateral head of gastrocnemius in patients (P＜0.05) and the evoked potentials in lateral head of gastrocnemius demonstrated significantly higher amplitude than in the medial head of gastrocnemius in healthy patients (P＜0.05). 2. Mean latency of the evoked potentials by a tendon reflex in both heads of gastrocnemius in the spastic patients and healthy subjects were not significantly different (P＞0.05). 3. Mean duration of the evoked potentials by a tendon reflex in both heads of gastrocnemius in spastic patients and healthy subjects were not significantly different (P＞0.05).
Conclusion: These results indicate that the medial head of gastrocnemius is activated more than the lateral head of gastrocnemius by a tendon reflex in recording evoked potentials of the spastic patients.
