Bell's Palsy

Question 1

Define Bells Palsy

Answer 1

idiopathic lower motor neurone facial nerve palsy

Question 2

Explain the aetiology/risk factors of Bell’s palsy

What is the epidemiology of Bells palsy?

Answer 2

IDIOPATHIC

60% are preceded by an upper respiratory tract infection

This suggests that it has a viral or post-viral aetiology

Most cases: 20-50 yrs

Question 3

Recognise the presenting symptoms of Bell’s palsy

Answer 3

Prodrome of pre-auricular pain (in some cases)

This is followed by unilateral facial weakness and droop

Maximum severity: 1-2 days

50% experience facial, neck or ear pain or numbness

Hyperacuisis
-This is due to stapedius paralysis (as CN7 supplies this)

Loss of taste (uncommon)

Tearing or drying of exposed eye

Because it may be difficult to close the eye fully

Question 4

Recognise the signs of Bell’s palsy on physical examination

Answer 4

1. Lower motor neurone weakness of facial muscles
   
   • Affects ipsilateral muscles of facial expression
   • Does NOT spare the muscles of the upper part of the face (unlike upper motor neurone facial nerve palsy) - so in stroke their forehead is not paralysed
2. Bell’s Phenomenon ;
   - Eyeball rolls up but the eye remains open when trying to close their eyes

• Despite reporting unilateral facial numbness, clinical testing of sensation is normal
• Examine the ears to check for other causes of facial nerve palsy (e.g. otitis media, herpes zoster infection)

Question 5

Identify appropriate investigations for Bell’s palsy

Answer 5

Usually unnecessary (except for excluding other causes)

EMG - may show local axonal conduction block

Question 6

Generate a management plan for Bell’s palsy

Answer 6

Protection of cornea with protective glasses/patches or artificial tears

High-dose corticosteroids is useful within 72 hrs

Only given if Ramsey-Hunt Syndrome is excluded

Surgery - lateral tarsorrhaphy (suturing the lateral parts of the eyelids together)
- Performed if imminent or established corneal damage

Question 7

Identify possible complications of Bell’s palsy

Answer 7

1. Corneal ulcers
2. Eye infection
3. Aberrant reinnervation (abnormal reinnervation)
   - E.g. Blinking may cause contraction of the angle of the mouth due to aberrant sympathetic innervation of orbicularis oculi and oris
   - Crocodile Tears Syndrome - parasympathetic fibres may aberrantly reinnervate the lacrimal glands causing tearing whilst salivating

Question 8

Summarise the prognosis for patients with Bell’s palsy

Answer 8

85-90% recover function within 2-12 weeks with or without treatment