Facial Nerve Palsy

Question 1

Facial Nerve (describe function, Innervation)

Answer 1

Responsible for:
1. Voluntary facial movement
2. Reflex facial movement
3. Emotional facial movement
Innervation:
1. Upper facial musculature receives innervation from both cerebral cortex and lower one has innervation from ipsilateral cortex only
2. Palsy of upper motor neuron (UMN) type results in paralysis of voluntary facial movement only while lower motor neuron (LMN) lesion results in absence of facial movements of all kind.

Question 2

Causes of Upper Motor Neuron Facial Palsy

Answer 2

1. Cerebral Vascular Accident
2. Associated with Hypertension
3. Brain Tumor

Question 3

Causes of Lower Motor Neuron Facial Palsy

Answer 3

A) Lesions outside the ear

1. Trauma- forceps delivery, lacerations
2. Infection - Parotitis
3. Parotid Tumor

B) Lesion inside the ear

1. Otitis Media
2. Mastoiditis
3. Ramsey Hunt Syndrome: Varicella infection of the geniculate ganglion
4. Bell’s Palsy

C) Brainstem Lesion

1. Moebius Syndrome
2. CVA affecting the brainstem
3. Tumor at the brainstem region
4. Acoustic Neuroma
5. Leukaemic infiltration

D) Others
1. Hypertension

Question 4

Causes of Bilateral Facial Palsy

Answer 4

1. Moebius Syndrome
2. Diphtheria
3. Guillian Barre Syndrome
4. Sarcoidosis

DDx: Myasthenia Gravis and Myotonia Dystrophica

Question 5

Steps in clinical examination of Facial Nerve Palsy

Answer 5

A. Spot the features suggesting facial nerve palsy

1. Eyebrow - different levels (lower at the affected side)
2. Eye - Not closed
3. Nasolabial fold - Flatterned
4. Drooling of saliva

B. Distinguish upper from lower motor neuron type lesion

C. If UMN affecting the facial nerve:
1. Look for hemiparesis of same side (Cortical damage - speech defect; visual field defect; sensory losss; astereognosis; agraphia; Loss of 2 point discrimination and sensory neglect)

2. Complete neurological examination, including fundi
3. Listen for cranial / cervical bruit
4. Examination of CVS - cardiac murmur, cyanosis and measure BP

D. If LMN lesion is detected:
1. Look for: Eye- for Squint; Parotid swelling/ scar; swelling and tenderness of mastoid air cells; Ear - hearing defect, vesicular lesions at drum/ ear canal / pinna, evidence of otitis media; Lip/ facial oedema and furrowed tongue

2. Neurological examination for other cranial nerve palsy (Hemiparesis- Contralateral; Ataxia)
3. Measure BP