Facial nerve palsy

Mild left facial nerve palsy. Note the 
slightly drooping of the corner of the 
left lip.

Getting the patient to smile reveals 
asymmetry of the action of the facial 

Getting the patient to forcibly shut her 
eyes. The left lashes are not buried due 
to the decreased tone of orbicularis oculi.

The most common type of facial nerve palsy seen is unilateral lower facial nerve palsy. Supranuclear facial nerve is 
uncommon in ophthalmology examination because the eyes are not involved. Remember not to use the term Bell's palsy 
as synonymous with lower facial nerve palsy; Bell's palsy is a diagnosis of exclusion when other known causes of lower 
facial nerve palsy has been considered.

The patient has loss of nasolabial fold and the forehead wrinkles of the affected side (in severe cases, there may be dropping 
of the corner of the mouth and obvious ectropion). The eyebrow of the affected side is lower (brow droop) and the upper lid
is retracted (ie. a wider palpebral aperture due to the unopposed action of the levator). The blink rate on the affected side is 
reduced. There is impaired blowing of the cheek, and asymmetrical movement of the corner of the lip on smiling. On eyelid 
closure, the affected side could not close the eye lid fully (or it can be easily opened).

Important additional testing (to assess the risk of exposure keratitis):

  • Check for Bell's phenomenon, by observing if the eyes move up on attempted lid closure (you may need to keep the

  • eyelids open to observe this but avoid hurting the patient)
  • Test the cornea sensation.
Further examination for any signs of aberrant regeneration suggesting the lesion is long-standing, the following signs are 
the most common:
  • Look for twitching of the mouth when the patient blink 
  • Look for closure of the eye or asymmetrical narrowing of the palpebral fissure on smiling

Further examination for the cause of the facial nerve palsy 
(the facial nerve is in close proximity to V and VI nerve which may become involved if the lesion were intracranial):

  • Any signs of vesicles on the external ear ? (Ramsey-Hunt's Syndrome)
  • Any signs of parotid swelling or scar over the parotid gland? (sarcoidosis, parotid gland tumour or recent parotid 

  • gland operation)
  • Any signs of deafness? (previous mastoid abscess)
  • Any loss of cornea and facial sensation? (cerebellopontine lesion)
  • Any scar behind the ear or behind the neck? (previous mastoid operation or acoustic neuroma operation)
  • In patient with contralateral hemiplegia, test the eye movement for ipsilateral gaze palsy and loss of facial sensation 

  • from fifth nerve involvement (Foville's Syndrome).


1. How can you determine the level of lower facial nerve palsy?


2. What is crocodile tear?


3. What is Merkelsson-Rosenthal's Syndrome?


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Right facial nerve palsy with poor lid closure. The patient
has a good right Bell's phenomenon (up-rolling of the
globe on eye closure).
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Vesicles on the pinna of a patient with right facial nerve
palsy. This appearance is typical of herpes zoster
(Ramsey-Hunt's Syndrome). The eruption usually involves
a small area over the pinna which receives sensory branch
from the facial nerve.
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A patient with a left surgical scar from parotid gland adenoma surgery. The facial nerve
is termed the 'hostage' of the parotid gland because it passes through the gland on its
way to innervate the muscles of facial expression. Surgery on the parotid gland inevitably
causes facial nerve palsy which is usually transient.
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