Bell's Palsy

Question 1

What is bell’s palsy?

Answer 1

Bell’s palsy is an idiopathic syndrome that causes damage to the facial nerve, characterised by:
- Acute unilateral peripheral facial nerve palsy in patients for whom physical examination and history are otherwise unremarkable.
- Deficits affecting all facial zones equally that fully evolve within 72 hours

Question 2

What causes bell’s palsy?

Answer 2

• 60% are preceded by an upper respiratory tract infection → suggests a viral or post-viral aetiology
• Herpes simplex virus type 1 (HSV-1) has strong correlation with Bell’s Palsy.
• RF = pregnancy

Question 3

What are the presenting symptoms/ signs of bell’s palsy?

Answer 3

1. Unilateral facial weakness and droop
2. Non-Forehead Sparing → LMN Lesion (ipsilateral) (forehead sparing indicates a contralateral UMN lesion, eg. stroke)
3. Involvement of all nerve branches → equal distribution to all facial nerve branches
4. Dry eye and mouth
   - Dry Eye ⇒ keratoconjunctivitis sicca
5. Loss of taste on anterior 2/3 of tongue
6. Hypersensitivity to loud noises → hyperacuisis
7. Involuntary and abnormal movements of face
8. Affects 1 entire side of the face (including forehead)  

Question 4

What investigations are used to diagnose/ monitor bell’s palsy?

Answer 4

1. CT/MRI - space occupying lesions 
2. EMG - may show local axonal conduction block in facial canal. Only useful >1 week after onset.
3. Bell’s phenomenon: Eyeball rolls up but eye remains open when trying to close the eyes. 

Question 5

How is bell’s palsy managed?

Answer 5

• Corticosteroids within 72 hrs (Oral Prednisolone)- 1st line treatment
• Eye Protection (Lid Taping or Lubricating Eye Drops) → dry eye is common and may lead to exposure keratopathy.
• If no signs of improvement after 3 weeks ⇒ urgent ENT referral
• Surgical Decompression & Anti-Virals (Acicolvir) if severe palsy