Depression of involuntary activity in muscle paralyzed by spinal cord injury

Jane E. Butler, Sharlene Godfrey, Christine K. Thomas

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Involuntary muscle contractions are common after spinal cord injury (SCI). Increased sensitivity to Ia muscle afferent input may contribute to the development of these spasms. Since tendon vibration results in a period of postactivation depression of the Ia synapse, we sought to determine whether Achilles tendon vibration (80 Hz for 2 s) altered involuntary contractions evoked by superficial peroneal nerve (SPN) stimulation (5 pulses at 300 Hz) in paralyzed leg muscles of subjects with chronic (>1 year) SCI. Responses to SPN stimulation that were conditioned by vibration were reduced in 66% of trials (by 33 ± 12% in tibialis anterior and 40 ± 16% in soleus). These reductions in electromyographic activity are unlikely to be mediated by changes at the Ia synapse or motoneuron because vibration did not alter the magnitude of the soleus H reflex. The electromyographic reductions may involve long-lasting neuromodulatory effects on spinal inhibitory interneurons or synapses involved in the flexor reflex pathway. Vibration-evoked depression of electromyographic activity may be clinically useful in controlling involuntary muscle contractions after SCI.

Original languageEnglish (US)
Pages (from-to)637-644
Number of pages8
JournalMuscle and Nerve
Issue number5
StatePublished - May 2006


  • Cutaneous nerve stimulation
  • Muscle spasm
  • Paralyzed muscle
  • Tendon vibration

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)


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