What is the role of conduction testing and electromyography (EMG) in the diagnosis of Bell palsy (idiopathic facial paralysis) (IFP)?

Updated: Jun 14, 2019
  • Author: Danette C Taylor, DO, MS, FACN; Chief Editor: Selim R Benbadis, MD  more...
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Useful tests for evaluation of the function of the facial nerve include nerve conduction testing and EMG. Nerve conduction velocities and EMG produce a graphic readout of the electrical currents, displayed by stimulating the facial nerve and recording the excitability of the facial muscles it supplies. These tests may aid in assessing the outcome of a patient who has persistent and severe Bell palsy.

This testing is not part of the acute workup; the tests are most useful when performed 3–10 days after the onset of paralysis. Note that most electromyographic/nerve conduction studies do not show an abnormality for 3 weeks following a peripheral nerve injury.

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