Bell's Palsy

Question 1

What is a Bell’s Palsy?

Answer 1

Acute neurological condition that presents with a rapid onset of unilateral facial paralysis (usually less than 72 hours)

Question 2

What causes Bell’s Palsy?

Answer 2

Unknown origin

Question 3

What type of lesion is Bell’s palsy?

Answer 3

Lower motor neuron lesion

Question 4

What nerve does Bell’s palsy effect?

Answer 4

7th cranial nerve (facial nerve)

Question 5

What do the motor fibres, carried by the facial nerve, innervate?

Answer 5

Motor fibres innervate the muscles of facial expression

Question 6

What do the sensory fibres that the facial nerve carries do?

Answer 6

The sensory fibres provide taste to the anterior tongue

Question 7

What do the parasympathetic fibres that are carried by the facial nerve do?

Answer 7

The parasympathetic fibres go to the lacrimal and salivary glands

Question 8

What are the three key components that are affected in Bell’s Palsy?

Answer 8

Motor component = unilateral facial weakness
Sensory component = altered taste
Parasympathetic component = dry mouth

Question 9

What is the prevalence of Bell’s palsy per year?

Answer 9

20-30 per 100,000

Question 10

What are the risk factors for developing a Bell’s palsy?

Answer 10

Age 15-45 years
Pregnancy 
Diabetes mellitus
Recent upper respiratory tract infection
Intranasal influenza vaccination (no longer in use)

Question 11

What are the symptoms of a Bell’s palsy?

Answer 11

Unilateral fcaial weakness
Altered taste
Hyperacusis (noise sensitivity)
 - Due to paralysis of stepedius muscle (which is innovated by VII)
Dry mouth + dry eyes
Ear pain 
 - seen in upto 50% of patients

Question 12

What is the key primary differential between a stroke and Bell’s palsy?

Answer 12

Bell’s patients cannot raise eyebrows whereas patients with a stroke can move their forehead (fore-head sparing) as it receives innovation from both sides of the brain

N.B. Absence of other weakness/sensory disturbance to upper and lower limbs in Bell’s Palsy

Question 13

What are the signs of a Bell’s palsy?

Answer 13

Facial paralysis

• Inability to move facial expressions on affected side
• Forehead is affected
• Inability to raise eyebrows

Change in taste to the anterior tongue

Unable to fully close eyes

Question 14

What is the predicted pathophysiology of Bell’s palsy?

Answer 14

Herpes simplex 1 within geniculate ganglion

Reactivation results in destruction of ganglion cells and infection of Schwann cells

Question 15

How is Bell’s palsy diagnosed?

Answer 15

Diagnostic investigations are not required = Bell’s palsy is clinical diagnosis + ‘diagnosis of exclusion’

Question 16

What investigations should be considered if an alternative cause of the facial palsy is suspected?

Answer 16

CT/MRI - view facial nerve and surrounding structures

Infectious disease screen - HIV, syphilis, Lyme disease, glandular fever

Angiotensin-converting enzyme (ACE) - sarcoidosis can present with bilateral facial nerve palsy
Serum ACE used as screening tool

Question 17

What is the management for Bell’s palsy?

Answer 17

Oral prednisolone - if patient presents within 72 hours of onset of symptoms

Anti-virals e.g. aciclovir - not recommended alone but considered in combination with corticosteriod

Eye protection - eye care discussed with patients + prescription of artificial tears + eye lubricants

Question 18

What are the complications of a Bell’s palsy?

Answer 18

Eye injury
Facial pain
Psychological disturbance - increased risk of depression

Question 19

How long will it take for patients to recover from a Bell’s palsy?

Answer 19

70% of patients recover their motor function completely within six months without any treatment

30% of patient have incomplete recovery or residual effects

Question 20

What factors indicate a poor prognosis for a Bell’s palsy?

Answer 20

old age, hypertension, diabetes mellitus and taste impairment