Bell's palsy

Question 1

Define:

Answer 1

• Idiopathic lower motor neurone facial nerve palsy

Question 2

Aetiology/risk factors:

Answer 2

IDIOPATHIC.
60% are preceded by an URTI
So may have viral/post-viral aetiology
Diagnosis of exclusion as 30% have defined causes

Question 3

What factors distinguish a Bell’s palsy:

Answer 3

 Abrupt onset with complete unilateral facial weakness at 24-72hours
 Ipsilateral numbness or pain from around the ear
 Reduced taste
 Hypersensitivity to sounds

Question 4

Epidemiology:

Answer 4

• Most cases: 20-50 yrs
• 15-40/100,000/yr
• Risk increases with pregnancy and in diabetes

Question 5

Symptoms:

Answer 5

• Abrupt onset
• 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 – hypersensitivity to sound
o This is due to stapedius paralysis
• Loss of taste (uncommon)
• Tearing or drying of exposed eye
o Because it may be difficult to close the eye fully
o Can cause conjunctivitis
• Drooling of saliva
• Food trapped between gum and cheek
• Speech difficulty

Question 6

Signs:

Answer 6

• Lower motor neurone weakness of facial muscles (Affects ipsilateral muscles of facial expression BUT Does NOT spare the muscles of the upper part of the face

• Bell’s Phenomenon
o Eyeball rolls up but the eye remains open when trying to close their eyes

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 – Ramsay-Hunt Syndrome)

Question 7

Investigations:

Answer 7

• Usually unnecessary (except for excluding other causes)
 ESR - infection
 Glucose – exclude DM (systemic disease can cause VII palsy)
 Borrelia antibodies – high in Lyme disease
 VZV antibodies – high in Ramsay Hunt Syndrome
 MRI: check for space-occupying lesions such as acoustic neuroma/meningioma, check for MS
 Nerve conduction tests
• EMG - may show local axonal conduction block

Question 8

Management:

Answer 8

• Protection of cornea with protective glasses/patches or artificial tears
Use tape to close eyes at night
• High-dose corticosteroids is useful within 72 hrs e.g. prednisolone
o Only given if Ramsey-Hunt Syndrome is excluded
o Speeds recovery
• Surgery
o Performed if imminent or established corneal damage
o Can do a lid loading procedure e.g. with gold
o If severe: lateral tarsorrhaphy (suturing the lateral parts of the eyelids together)
• Botulinum toxin can augment facial symmetry

Question 9

Complications:

Answer 9

Corneal Ulcers
Conjunctivitis

Aberrant reinnervation
o Crocodile Tears Syndrome - parasympathetic fibres may aberrantly reinnervate the lacrimal glands causing tearing whilst salivating

Question 10

Prognosis:

Answer 10

• 85-90% recover function within 2-12 weeks with or without treatment
• Incomplete paralysis usually recovers completely
• Complete paralysis – 80% make full recovery