Characteristics of lower extremity clonus after human cervical spinal cord injury.

Clonus can interfere with self-care and rehabilitation of people with spinal cord injury. Our aim was to characterize clonus and to evaluate factors that influence clonus duration in muscles paralyzed chronically by spinal cord injury. Electromyographic activity was recorded from soleus and 7 other limb muscles (5 ipsilateral, 2 contralateral) during clonus.

Motor unit behavior during clonus.

Medial gastrocnemius surface electromyographic activity and intramuscular electromyographic activity were recorded from six individuals with chronic cervical spinal cord injury to document the recruitment order of motor units during clonus. Four subjects induced clonus that lasted up to 30 s while two subjects induced clonus that they actively stopped after 1 min. Mean clonus frequency in different subjects ranged from 4.