Bell’s palsy

Question 1

What is Bell’s palsy?

Answer 1

Bell’s palsy = idiopathic unilateral LMN facial (CN7) nerve palsy (Not upper facial muscle sparing as LMN lesion)

DIAGNOSIS BY EXCLUSION

Question 2

What is the aetiology of Bell’s palsy?

Answer 2

Idiopathic
60% preceded by URTI – suggesting a viral/post viral aetiology

Evidence points to a reactivation of HSV-1 in the geniculate ganglion

Question 3

What are the risk factors for Bell’s palsy?

Answer 3

• IN influenza vaccination
• Pregnancy
• URTI
• Black/Hispanic
• Cold climate
• FH

Question 4

What is the epidemiology of Bell’s palsy?

Answer 4

Most common aetiology of unilateral facial palsy among over 2s (Most prevalent aged 15-50)

Equally distributed between genders and sides of the face

Annual incidence of 15-40 in 100,000

Question 5

What are the presenting symptoms of Bell’s palsy?

Answer 5

• Prodrome of pre-auricular pain
• Acute (hours/days) onset unilateral facial weakness and droop (Maximum severity in 1-2 days)
• Facial/neck/ear pain/numbness
• Hypersensitivity to sound
• Tearing/drying of exposed eye

Question 6

What are the signs of Bell’s palsy?

Answer 6

o Involvement of all nerve branches
o Unilateral
o Does not spare forehead

Bell’s phenomenon
o Eyeball rolls up but eye remains open when trying to close the eyes
o Clinical sensation is normal

Question 7

What investigations are done for Bell’s palsy?

Answer 7

Clinical diagnosis - Diagnosis by exclusion
o Acute, unilateral facial palsy
o Otherwise normal physical examination

EMG
o Absence of voluntary motor unit potentials – local axonal conduction block in facial canal
o Only useful >1 week after diagnosis

Exclude other diagnoses
o	Serology
o	Borrelia burgdorferi: Negative (Lyme disease)
o	Neck exam – parotid 
o	Ear exam

Question 8

What is the management of Bell’s Palsy?

Answer 8

Protection of cornea
o Protective glasses/patches
o Artificial tears

Steroids (if severe)
o Prednisolone

Anti-viral therapy (if ongoing viral cause)
o Acyclovir

Surgery
o Lateral tarsorrhaphy if imminent/established corneal damage - Involves suturing the lateral parts of the eyelids together

Question 9

What is the prognosis of Bell’s Palsy?

Answer 9

85-90% recover function in 2-12 weeks without treatment.

Question 10

What are the possible complications of Bell’s Palsy?

Answer 10

Corneal ulcers (ulcerative keratitis)
Dry eye (keratoconjunctivitis sicca)
Eye infection

Synkinesis
o Caused by aberrant regeneration
o Blinking may cause contraction of angle of mouth

Crocodile tears (Gustatory hyperlacrimation)
o	Lacrimation upon swallowing