The natural occurrence of contractions of several muscles when volition calls but one of the muscles into action has been of interest to the neurophysiologist for a long time. Usually, the synkinesis is operative in only one way. For instance, in Bell's phenomenon the closure of the eyelids is accompanied by an upturning of the eyeball, not vice versa. Such associated movements have been recognized as expressions of reflex and coordinative mechanisms within the central nervous system.The unnatural appearance of an unwilled contraction of a muscle when another muscle is called into action has intrigued clinicians and has provoked much thought and speculation. Sometimes such pathologic synkineses have been noted early in life or have not been associated with any history or evidence of disease or trauma. These have been assumed to be congenital or even hereditary in origin. Most times, the associated movements have occurred with a
SCHWARZ GA. A Note on an Unusual Facio-Ocular Synkinesis. Arch Neurol. 1962;6(5):358–365. doi:10.1001/archneur.1962.00450230020003
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