Bell's Palsy

Question 1

What is Bell’s Palsy defined as?

Answer 1

An idiopathic LOWER MOTOR NEURONE facial nerve palsy

Question 2

What are the aitiology/ risk factors of Bell’s Palsy?

Answer 2

• Mainly idiopathic

- 60% of cases are preceded by an upper respiratory tract infection suggesting a viral/ post-viral aitiology

Question 3

What is the general epidemiology of Bell’s Palsy?

Answer 3

Most cases are present in 20-50 year olds

Question 4

Presenting complaints of Bell’s Palsy

Answer 4

• In some cases you may have pre-auricular pain prodromally
• Followed by an unilateral facial weakness and droop
  (Lasting 1-2 days)
• 50% -> facial, neck or ear pain/ numbness
• Hyperacuisis -> Due to stapedius muscle paralysis
• Uncommonly presents with loss of taste
• Tearing or drying of exposed eye -> due to increased difficulty to close eyes fully

Question 5

Signs of Bell’s on physical examination

Answer 5

• Lower motor neurone weakness of facial muscles- affecting ipsilateral muscles of facial expression and does NOT spare the muscles of the upper part of the face (unlike upper motor neurone facial nerve palsy)
• 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 6

Appropriate investigations for Bell’s Palsy

Answer 6

• Usually unnecessary (except for when excluding other causes)
• EMG - may show local axonal conduction block

Question 7

Management for Bell’s Palsy

Answer 7

• 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 8

Complications of Bell’s Palsy

Answer 8

• Corneal ulcers
• Eye infection
• Aberrant 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 9

Prognosis for Bell’s Palsy

Answer 9

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