What is the pathophysiology 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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The precise pathophysiology of Bell palsy remains an area of debate. The facial nerve courses through a portion of the temporal bone commonly referred to as the facial canal. A popular theory proposes that edema and ischemia result in compression of the facial nerve within this bony canal. The cause of the edema and ischemia has not yet been established. This compression has been seen in MRI scans with facial nerve enhancement. [14]

The first portion of the facial canal, the labyrinthine segment, is the narrowest; the meatal foramen in this segment has a diameter of only about 0.66 mm. This is the location that is thought to be the most common site of compression of the facial nerve in Bell palsy. Given the tight confines of the facial canal, it seems logical that inflammatory, demyelinating, ischemic, or compressive processes may impair neural conduction at this site.

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