Facial nerve palsy

• a facial nerve palsy is paralysis of the facial nerve.
• the facial nerve is the motor supply to the scalp, facial muscles and stapedius. It also supplies taste in the anterior 2/3 of the tongue via the chorda tympani branch.
• the course of the facial nerve through the posterior fossa, temporal bone, and parotid gland makes it vulnerable to many neoplastic, traumatic, and infectious events (1)
• a peripheral facial paralysis requires a complete head and neck examination including the following:
  • otoscopy
  • cranial nerve evaluation. (1)
• the function of the facial nerve is tested as follows in the neurological examination:
  • brow:
    • the patient is asked to raise the eyebrows
    • the brow is spared in a unilateral upper motor neurone lesion - for example a stroke affecting one half of the face will spare the brow
    • if there is an upper motor neurone lesion affecting the facial nerve then the ability to wrinkle the brow is preserved; in Bell's palsy this ability is lost
  • eyes:
    • the patient is asked to screw up the eyes and resist attempts by the examiner to open the eyes
  • facial movement:
    • smiling, blowing out the cheeks, etc.

Reference

1. Libreros-Jiménez HM, Manzo J, Rojas-Durán F, et al. On the cranial nerves. NeuroSci. 2024 Mar;5(1):8-38.