F-waves of the facial muscles in healthy control subjects and in patients with peripheral facial nerve disturbance

M. Ishikawa, J. Namiki, M. Takase, A. Kojima, T. Kawase

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


F-waves were recorded from the mentalis muscles with surface electrodes following stimulation of the marginal mandibular branch of the facial nerve in healthy control subjects during wakefulness, non-REM (rapid eye movement) sleep and voluntary contraction and in patients with Bell's palsy and acoustic neurinoma. The F-wave of the facial muscles results from the backfiring of antidromically activated alpha motoneurons in the facial motonucleus. Therefore, first, the F-waves were not easily elicited in patients with any disturbance in the proximal segment of the facial nerve (Bell's palsy and acoustic neurinoma). Second, the F-waves were affected by excitability of the facial motonucleus; the F-waves were inhibited significantly during sleep and enhanced significantly during voluntary contraction compared with those at rest during wakefulness. When the stimulation strength was set submaximum for M-waves, F-waves were elicited but H-waves, which have lower threshold than M-waves, were not elicited in the facial muscles, unlike the case of extremities. Measurement of the F- waves of facial muscles is a new method for estimating excitability of the facial motonucleus unless there is any disturbance of the proximal segment. Fundamental characteristics of the facial F-waves were shown in the present study and measuring facial F-waves is clinically applicable for investigation of both excitability of the facial motonucleus and facial peripheral nerve disturbance.

Original languageEnglish
Pages (from-to)167-174
Number of pages8
JournalElectromyography and Clinical Neurophysiology
Issue number3
Publication statusPublished - 1999 Apr


  • Bell's palsy
  • Late response
  • Neurinoma
  • Sleep
  • Voluntary contraction

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Physiology (medical)


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