Segmental facial myoclonus in Moebius syndrome

Paolo Bonanni, Renzo Guerrini

Research output: Contribution to journalArticlepeer-review


Moebius syndrome is characterized by sixth and seventh nerve palsy and is usually the result of bilateral hypoplasia or aplasia of the respective brain stem nuclei. There have been no reports of involuntary facial movements associated with this malformative complex. We report on a 6-year-old boy affected by Moebius syndrome with asymmetric involvement and segmental facial myoclonus with onset at age 2 years, affecting the side with partially conserved motility. Clinical presentation included congenital peripheral palsy of the right seventh cranial nerve and left-sided rhythmic rising of the upper lip and eyebrow. Surface-electromyography (EMG) of the left levator labii and frontalis muscles showed rhythmic bursting (duration: 150-450 ms; frequency: 1-3 Hz). Electroencephalographic (EEG)-polygraphic recordings and burst-locked EEG averaging failed to show any consistent EEG activity preceding the EMG bursts. Study of the blink reflex, somatosensory and motor-evoked potentials showed findings consistent with pontine pathology. Segmental facial myoclonus, although extremely rare in children, must be differentiated from several other paroxysmal motor manifestations associated with structural lesions involving the brain stem.

Original languageEnglish
Pages (from-to)1021-1024
Number of pages4
JournalMovement Disorders
Issue number6
Publication statusPublished - 1999


  • Brain stem
  • Moebius syndrome
  • Segmental facial myoclonus
  • Structural lesion

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)


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