Bell's Palsy

Question 1

Define Bell’s Palsy

Answer 1

An acute, unilateral, idiopathic facial nerve paralysis

Question 2

What age range has the peak incidence?

Answer 2

20 to 40

Question 3

When does risk increase?

Answer 3

During pregnancy and in diabetes

Question 4

What symptoms and signs are associated?

Answer 4

Unilateral facial weakness (forehead affected as a LMN palsy)
Ipsilateral numbness or pain around ear
Altered taste
Hypersensitivity to sound (stapedius palsy)
Dry eyes
Sagging of mouth
Absence of nasolabial fold
Drooling of saliva
Food trapped between gum and cheek
Speech difficulty
Failure of eye closure may cause watery or dry eye, ectropian, injury or infection to eye

Question 5

Does Bell’s Palsy affect UMN or LMN?

Answer 5

LMN facial nerve

Question 6

In the case of a stroke, why is the forehead spared? (Unlike in Bell’s palsy)

Answer 6

A stroke is an UMN lesion.

The upper part of the face has ipsilateral and contralateral innervation from UMNs, unlike the lower halves of the face, which just have ipsilateral supply. In a stroke, the lesion is on one side of the brain, so the upper part of the face will still get supply from the contralateral side (unlike the lower half).

Question 7

What does the stapedius muscle do?

Answer 7

Dampens vibrations of the stapes bone - this is why in Bell’s palsy you can get hyperacousis

Question 8

The facial nerve carries sensation from what part of the face?

Answer 8

Anterior 2/3 or tongue

Question 9

What causes Bell’s palsy?

Answer 9

Precise cause is unknown
Likely viral infections - herpes simplex, Epstein Barr, varicella zoster
Bacterial - the bacteria that causes Lyme disease

Question 10

How is Bell’s palsy diagnosed?

Answer 10

Identifying a problem with the facial nerve and not finding an alternative explanation e.g stroke or tumour

Bloods - ESR, glucose
CT/MRI - space occupying lesion, stroke, MS
CSF (rarely done) - infections

Question 11

What is the prognosis?

Answer 11

Incomplete paralysis - most recover within a few weeks

Complete paralysis - most make a full recovery, but 15% have axonal degeneration, so recovery delayed

Question 12

How is it managed?

Answer 12

Treatment often not needed
In severe cases: prednisolone within 72 hours of onset can speed recovery
Antivirals do not help
Protect the eye - dark glasses, artificial tears, tape to close eye at night

Question 13

What are some other causes of CN VII palsy?

Answer 13

Think of these if rashes, bilateral symptoms, UMN signs, other CN involvement, limb weakness

Infective - Ramsey hunt syndrome, Lyme disease, meningitis, TB, viruses
Brainstem lesion - stroke, tumour, MS
Systemic - DM, sarcoidosis, Guillian- Barre
Local - parotid tumour, otitis media, cholesteatoma, skull base trauma