How is hemifacial spasm diagnosed?

Updated: Sep 16, 2019
  • Author: Steven Gulevich, MD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Answer

Early cases of hemifacial spasm may be difficult to distinguish from facial myokymia, tics, or myoclonus originating in the cortex or brainstem. Neurophysiologic testing can be invaluable.

Spread and variable synkinesis on blink reflex testing and high-frequency discharges on electromyography (EMG) with appropriate clinical findings are diagnostic. Stimulation of one branch of the facial nerve may spread and elicit a response in a muscle supplied by a different branch. Synkinesis is not present in essential blepharospasm, dystonia, or seizures. Needle EMG shows irregular, brief, high-frequency bursts (150–400 Hz) of motor unit potentials, which correlate with clinically observed facial movements.


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