Disease modifying treatment available:
Time critical diagnosis and management:
Lateralising:
Dysfunction of the facial nerve
The facial nerve is involved in several processes:
- Motor innervation to muscles of facial expression
- Taste in the anterior 2/3rds of the tongue
| Disorder | Clinical features | Associated features | Investigations | Disease modifying treatment available | Time critical |
|---|---|---|---|---|---|
| Guillain-Barre syndrome |
Peripheral neuropathy Respiratory failure type 2 Demyelinating peripheral neuropathy Acute polyneuropathy |
||||
| Human immunodeficiency virus 1 infection |
Peripheral neuropathy |
||||
| Sjögren syndrome |
Dry eyes Dry mouth Longitudinally extensive myelitis Demyelinating peripheral neuropathy Peripheral neuropathy |
||||
| Syphilis |
Dementia Sensorineural hearing loss |
||||
| Tuberculosis |
Peripheral neuropathy Cough Breathlessness Haemoptysis Recurrent cranial neuropathies Optic neuropathy Uveitis |
||||
| Bell's palsy | |||||
| Melkersson-Rosenthal syndrome | |||||
| Lyme disease |
First degree heart block Erythema migrans Acute polyneuropathy |
||||
| Parotid neoplasm | |||||
| Foville syndrome | |||||
| Ramsay Hunt syndrome | |||||
| Gradenigo syndrome | |||||
| Otitis media | |||||
| Millard-Gubler syndrome |
Sixth nerve palsy Weakness |
||||
| Sarcoidosis |
Breathlessness Recurrent cranial neuropathies Longitudinally extensive myelitis Peripheral neuropathy |
||||
| Möbius syndrome |
Sixth nerve palsy |
Cataplexy |
It is helpful to consider three major muscles during clinical testing of the motor function of the facial nerve:
- Frontalis - bilateral innervation
- Orbicularis oculi - predominantly unilateral (contralateral) but some bilateral contribution
- Orbicularis oris - unilateral innervation (contralateral)
The various patterns of weakness of frontalis, orbicularis oculi and orbicularis oris allow determination of whether a facial nerve lesion is the result of an upper motor neuron lesion or a lower motor neuron lesion. Damage to the upper motor neuron causes contralateral weakness primarily of orbicularis oris with lesser involvement of orbicularis oculi. Damage to the lower motor neuron results in weakness of orbicularis oculi and orbicularis oris.
The facial nerve provides taste innervation to the anterior two-thirds of the tongue.
The ear should be inspected for vesicles which may be seen in Ramsay Hunt syndrome. The parotid gland should be examined for masses. A history of twitching of the face prior to onset is suggestive of irritation of the nerve and imaging should be obtained.
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