Bell's Palsy

Question 1

Define Bell’s palsy

Answer 1

Acute idiopathic lower motor neuron facial nerve palsy

Question 2

What are the causes/risk factors of Bell’s palsy?

Answer 2

Idiopathic
60% are preceded by an URTI (? viral or post viral aetiology)
70% fully recover without any treatment

Question 3

What are the symptoms of Bell’s palsy?

Answer 3

• Pre-auricular pain
• Acute onset unilateral facial weakness
• Face/neck/ear pain or numbness
• Hyperacusis (stapedius paralysis)
• Dysgeusia
• Keratoconjunctivitis sicca – dry eye
• Epiphoria – tearing

Question 4

What are the signs of Bell’s palsy?

Answer 4

• Ipsilateral LMN weakness of facial muscles including forehead
• Bell’s phenomenon: Eyeball rolls up but eye remains open when trying to close the eyes.
• Although patient may report unilateral facial numbness, clinical testing of sensation is normal.
• The ear should be examined to exclude other causes (e.g. otitis media, herpes zoster infection).

Bell’s Palsy is a diagnosis of exclusion. Red Flags that point to another cause include:
• Uneven distribution of weakness across the facial zones.
• Headache, fever or malaise.
• Bilateral pathology
• Prior episode of facial palsy
• Persistence of complete flaccid paralysis at 3-4 months
• Presence of other cranial or peripheral neuropathies
• Presence of otological symptoms other than mild to moderate otalgia and hyperacusis,

• Severe otalgia in the absence of vesicles suggests: Ramsay Hunt Syndrome.
• Malaise, myalgia, fever, rash, and/or frontal headache, history of tick bites, or travel to a Lyme disease-endemic area: Lyme disease.
• Recurrent episodes of Bell’s palsy are rare: Autoimmune or granulomatous disease.
• Facial palsy that is insidious in onset or unevenly distributed across facial zones should prompt work-up for parotid or temporal bone neoplasm.

Question 5

What investigations are carried out for Bell’s palsy?

Answer 5

• Boriella Antibodies - positive in Lyme Disease.
• VZV Antibodies - positive in Ramsay-Hunt Syndrome
• MRI of CNVII Course - space-Occupying Lesions; Stroke; MS.
• EMG - may show local axonal conduction block in facial canal. Only useful >1 week after onset. Doesn’t influence treatment so not routinely done.

Question 6

What is the management for Bell’s palsy?

Answer 6

Conservative:
• Protection of cornea with protective glasses/patches and artificial tears.

Medical:
• High-dose corticosteroids (prednisolone) is beneficial within 72 h (given only if Ramsay Hunt’s syndrome is excluded).
• Little evidence for acyclovir.

Surgical:
• Lateral tarsorrhaphy (suturing the lateral parts of the eyelids together) if imminent or established corneal damage.

Question 7

What are the complications of Bell’s palsy?

Answer 7

• Corneal ulcers
• Eye infection
• Aberrant reinnervation may occur: Synkinesis –Blinking may cause contraction of the angle of the mouth as a result of simultaneous innervation of orbicularis oculi and ori.
• Parasympathetic fibres may also aberrantly reinnervate causing crocodile tears (gusto-lacrimal reflex) when salivating.