Dynamic Reanimation for Facial Paralysis Workup

Updated: Jan 27, 2020
  • Author: Steven M Parnes, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Workup

Laboratory Studies

Electrophysiologic testing is very useful in predicting recovery of neural functioning and determining motor endplate function. Electroneurography (ENoG) is useful in the acute period after facial paralysis. Within 5-14 days after injury, an ENoG study determines the percent of denervation. If 90% degeneration of the nerve is present, the prognosis for return of function is quite poor. In situations of smaller percent degeneration, the patient should be observed for 12-24 months for any return of facial nerve function.

Electromyography (EMG) is a beneficial examination 2 weeks after injury and beyond. The examination may show polyphasic action potentials of the examined muscle, which indicated active neural input and a good prognosis for eventual return of function. Fibrillations indicate denervation with intact motor endplates, which portends a poor prognosis for recovery of function without surgical intervention. Electrical silence, seen in the setting of prolonged facial paralysis, signifies that the motor endplates are no longer viable, and, therefore, nerve transposition procedures would ultimately fail.

If any doubt exists, a muscle biopsy always can be performed to observe for any surviving motor endplates. This procedure helps determine the appropriate techniques, such as nerve procedures, musculofascial transpositions, or static techniques.