Characteristics of Lower Extremity Clonus after Human Cervical Spinal Cord Injury

Clonus, rhythmic involuntary muscle contractions, can hinder rehabilitation in individuals with spinal cord injury. This study characterizes clonus in paralyzed muscles after spinal cord injury. The research aimed to understand factors influencing clonus duration, focusing on muscle activation patterns during these contractions. The study suggests that afferent input and localized spinal circuits play a significant role in the frequency and maintenance of clonus.

• 1
  Clonus frequency in the soleus muscle averaged 5.4 Hz and was slower when the reflex path was longer, indicating afferent input influences clonus.
• 2
  Prolonged clonus (>40 seconds) occurred when only ipsilateral triceps surae or triceps surae and tibialis anterior muscles were involved, highlighting the importance of localized spinal inputs.
• 3
  Clonus was shorter (<5 seconds) when both ipsilateral and contralateral muscles were activated, suggesting extraneous afferent input can shorten clonus after spinal cord injury.