Facial nerve palsy

Question 1

Facial nerve palsy : Definition

Answer 1

Facial nerve palsy refers to isolated dysfunction of the facial nerve.
This typically presents with a unilateral facial weakness.

Question 2

Facial nerve : Anatomy and physiology

Answer 2

1. Exit : via cerebellopontine angle in the Brainstem
2. Branches : Temporal, Zygomatic, Buccal, Marginal mandibular, Cervical
3. Function
   * Motor : muscles of facial expression, stapedius in the inner ear, neck muscles
   * Sensory : It carries taste from the anterior 2/3 of the tongue.
   * Parasympathetic : It provides the parasympathetic supply to the: salivary glands and lacrimal glands

Question 3

Facial nerve palsy : Pathophysiology - UMN

Answer 3

1. Facial motor nerves supply muscles in the face
   * Forehead supply;

Upper motor neurone :

Origin : Primary motor cortex } damage occurs <brainstem

Forehead : ‘Bilateral innervation’
* Each side of forehead:

• supplied by UMNs (2) from one from each hemispheres of the brain

Palsy : Forehead sparing (can be supplied from the UMN in the functional hemisphere)

Question 4

Facial nerve palsy : Pathophysiology - LMN

Answer 4

2) Lower motor neurone

• Origin : Brainstem } damage occurs > brainstem
• Forehead + Lower half of face : Ipsilateral innervation

Palsy : Both Forehead + lower face affected
* Same side of lesion affected

Question 5

Facial nerve palsy : Clinical features of UMN/LMN

Answer 5

Upper motor neurone lesion :
* Forehead sparing
* Weakness in lower face is contralateral to lesion

Lower motor neurone lesion :
* No forehead sparing
* U+L face weakness on same side as lesion

Question 6

Facial nerve palsy : Causes of UMN lesion

Answer 6

1. Unilateral upper motor neurone lesions occur in:
   * Cerebrovascular accidents (strokes)
   * Tumours
2. Bilateral upper motor neurone lesions are rare. They may occur in:
   * Motor neurone disease

Question 7

Facial nerve palsy : Causes of LMN lesion

Answer 7

1. Bell’s palsy
2. Ramsay-Hunt syndrome
3. Acoustic neuroma/Cholesteatoma
4. Infection : Otitis media/malignant otitis externa

Question 8

Bell’s palsy : Definition

Answer 8

An acute, unilateral, idiopathic, facial nerve paralysis due to inflammation of facial nerve

Question 9

Bell’s palsy : Cause

Answer 9

Assoc with : Herpes simplex virus

Question 10

Bell’s palsy : Incidence

Answer 10

• 20-40 years
• More common in pregnant women

Question 11

Bell’s palsy : Clinical features

Answer 11

Onset : Very acute
* Unilateral facial weakness : drooping of eye lids and mouth (no forehead sparing)
- Unable to close eyes
* Altered taste : supply of 2/3 anterior part of tongue affected
* Hyperacusis : Increases sensitivity to sound due to stadium muscle involvement

Question 12

Bell’s palsy : Management

Answer 12

1. < 72 hours from symptom onset
   * Oral prednisolone for 10 days
2. Eye lubricant/drops
3. No improvement > 3 week : ENT referral

Question 13

Bell’s palsy : Prognosis

Answer 13

Full recovery 3-4 months

Question 14

Ramsay Hunt syndrome : Definition

Answer 14

Lower motor neurone facial palsy caused by reactivation of varicella-zoster virus latent in the sensory nerve roots after initial chicken pox infection

Question 15

Ramsay Hunt syndrome : Pathophysiology

Answer 15

1. Varicella zoster activated : remained latent in sensory nerve root
2. Virus spreads along sensory nerves : Facial and Vestibulocochlear nerve effected
3. Inflammation of nerves

Question 16

Ramsay Hunt syndrome : Clinical features

Answer 16

• Unilateral facial palsy
• Vesicular rash around ear : painful and tender
• Assoc with VC nerve : Vertigo and tinnitus

Question 17

Ramsay Hunt syndrome : Management

Answer 17

Oral aciclovir and Corticosteroids