bell's palsy

Question 1

definition

Answer 1

Bell’s palsy is an acute unilateral peripheral facial nerve palsy in patients for whom physical examination and history are otherwise unremarkable, consisting of deficits affecting all facial zones equally that fully evolve within 72 hours. To date, it remains a clinical diagnosis of exclusion. Complete recovery to normal facial function occurs in approximately 70% of untreated cases, with permanently impaired facial function occurring to a minor degree in 13% and to a major degree in 16% of cases. Onset of clinical recovery is nearly always demonstrated within 4 to 6 months of symptom onset; absence of any return of hemi-facial tone or movement by this time is highly suggestive of an alternative diagnosis. Facial palsy of an otherwise known aetiology (e.g., Lyme disease-associated facial palsy), or facial palsy that is progressive, waxing and waning, or affects facial zones in an uneven fashion, is not Bell’s palsy.

Bell’s palsy is usually viral (herpes simplex virus) or idiopathic!!

Question 2

important points

Answer 2

• the forehead droop is seen here! (compared to stroke, where eyebrows are spared, because of the innervation from the unaffected side)
• abrupt onset (eg overnight or after a nap) with complete unilateral facial weakness at 24–72h; ipsilateral numbness or pain around the ear; reduced taste (ageusia); hypersensitivity to sounds (i.e. hyperacusis from stapedius palsy)

Question 3

symptoms

Answer 3

• abrupt onset (eg overnight or after a nap) with complete unilateral facial weakness at 24–72h;
• ipsilateral numbness or pain around the ear;
• reduced taste (ageusia);
• hypersensitivity to sounds (i.e. hyperacusis from stapedius palsy)
• Unilateral sagging of the mouth, which is drawn upwards on the normal side on smiling, causing a grimace
• Drooling of saliva
• Food trapped between gum and cheek
• Speech difficulty
• Failure of eye closure may cause a watery or dry eye, ectropion (sagging and turning-out of the lower lid), injury from foreign bodies, or conjunctivitis.

Question 4

signs/examination

Answer 4

CN 7 examination – facial movements, ask about changes in taste (CN7 innervates anterior 2/3 of tongue)

Question 5

investigations

Answer 5

1st investigations:
- clinical diagnosis (test CN 7 )
- electroneurography (ENoG) or evoked electromyography (eEMG)
- needle electromyography (EMG)
- bloods:
ESR; glucose; check for increased Borrelia antibodies in Lyme disease (indistinguishable clinically from Bell’s), check for increased varicella zoster virus (VZV) antibodies in Ramsay Hunt syndrome (BOX).
MRI: Space-occupying lesions; stroke; MS; CSF (rarely done) for infections.

basically, urgent ones:

• clinical diagnosis
• viral serology
• ENoG or eEMG or EMG

Question 6

treatment

Answer 6

1. prednisolone
   + eye protection

for patients presenting with severe/complete paralysis:
++ concurrent antiviral therapy – give together with prednisolone! (valaciclovir or aciclovir)
++ consider surgical decompression

Question 7

risk factors

Answer 7

• pregnancy (3x more likely to get bell’s palsy during pregnancy)
• diabetes mellitus

Question 8

prognosis

Answer 8

most patients with partial or full paralysis recover completely, but full paralysis may take longer to recover.
new abnormal reconnections may occur e.g. tearing when eating (lol).

Question 9

complications

Answer 9

axonal degeneration