Bell's Palsy

Question 1

Define Bell’s Palsy

Answer 1

Acute unilateral lower motor neurone facial nerve palsy

Question 2

Aetiology of Bell’s Palsy

Answer 2

Idiopathic
60% are preceded by an URTI (suggests viral or post-viral aetiology)

Suggested: reactivation of HSV-1 within the geniculate ganglion -> facial nerve conduction blockade

Question 3

Risk factors for Bell’s Palsy

Answer 3

Intranasal influenza vaccination
Pregnancy 
Upper respiratory tract infection 
Black/hispanic
Arid/cold climate
Hypertension
Family history 
Diabetes

Question 4

Symptoms of Bell’s Palsy

Answer 4

Preceding URTI + pain (post-auricular + otalgia)

Single episode of unilateral facial weakness and droop
May have facial, neck or ear pain/numbness (50%)
Hyperacusis (sensitivity to sound due to stapedius reflex involvement)
Dysgeusia (taste disturbance)

Question 5

Signs of Bell’s Palsy

Answer 5

Unilateral LMN weakness of facial muscles with NO forehead sparing
Bell’s phenomenon: eyeballs roll up but the eye remains open when trying to close the eyes
Clinical sensation is normal despite reported numbness
Keratoconjunctivitis sicca -> epiphora + hyperlacrimation
Synkinesis

Question 6

Investigations for Bell’s Palsy

Answer 6

Clinical diagnosis

Electroneuronography (ENoG): >90% in amplitude of compound muscle action potential
EMG: absence of voluntary motor unit potentials
Serology for Borrelia burgdorferi: negative (Lyme disease)

Question 7

Management for Bell’s Palsy

Answer 7

Acute

1. Corticosteroid e.g. prednisolone
2. Eye protection (glasses + artificial tears)

Severe palsy/paralysis
1. Concurrent antiviral therapy e.g. aciclovir
2. Surgical decompression
3, Lateral tarsorrhaphy (suture the lateral parts of the yield together) if corneal damage

Question 8

Complications of Bell’s Palsy

Answer 8

Keratoconjunctivitis sicca
Exposure keratopathy 
Ulcerative keratitis
Ectropion (sagging eyelid)
Contracture and synkinesis
Gustatory hyperlacrimation
Corneal ulcers

Question 9

Prognosis for Bell’s Palsy

Answer 9

Incomplete paralysis on clinical examination - 94% will fully recover
Complete paralysis - 61% will fully recover
Pregnancy-associated Bell’s may be associated with worse long-term outcomes