Bell's Palsy Flashcards
Define
idiopathic lower motor neurone facial nerve palsy
Causes
IDIOPATHIC
60% are preceded by an upper respiratory tract infection
This suggests that it has a viral or post-viral aetiology
Epidemiology
Most cases: 20-50 yrs
Symptoms
± Prodrome of pre-auricular pain
→ Acute (hours/days) onset of unilateral face weakness and droop
Maximum severity of face weakness/droop within 1-2 days
- 50%: facial/neck/ear pain or numbness
- Hypersensitivity to sound (due to stapedius paralysis)
- Tearing or drying of exposed eye
- Loss of taste (uncommon)
Signs
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)
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)
Investigations
Usually unnecessary (except for excluding other causes)
EMG - may show local axonal conduction block
Management
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
Management
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
Prognosis
