Bell's Palsy Flashcards
What is Bell’s palsy?
- acute unilateral peripheral facial nerve palsy
- physical examination and history are otherwise unremarkable
- consisting of deficits affecting all facial zones equally
- symptpms fully evolve within 72 hours.
- remains a clinical diagnosis of exclusion
In what % of pts with Bell’s palsy does complete recovery to normal facial function occur?
70%
small % are left with permanently impaired facial function
How long does it take for clinical recovery (Bell’s palsy)?
- 4 to 6 months of symptom onset;
lack of any return of hemi-facial tone / movement by this time is highly suggestive of an alternative diagnosis
Are the following symptoms in line with Bell’s palsy?
a) progressive palsy
b) waxing and waning palsy
c) palsy affecting facial zones in an uneven fashion,
a, b, c = NO
What is the cause of Bell’s palsy?
reactivation of HSV-1 within geniculate ganglion
What are the classifications of Bell’s palsy according to House-Brackmann scale (HBS)?
- Grade I = normal
- Grade II = slight weakness/asymmetry
- Grade III = obvious weakness with movement but absence of disfigurement at rest; intact ability to close the eye
- Grade IV = obvious weakness with movement and disfigurement at rest; inability to fully close the eye
- Grade V = barely perceptible movement
- Grade VI = no movement.
What are the risk factors for Bell’s palsy?
- intranasal inactivated flu vaccine - now discontinued
- pregnancy
What are the primary investigations for ?Bell’s palsy?
- thorough Hx and examination –> clinical diagnosis
What investigations should be conducted if the primary investigations are inconclusive for ?Bell’s palsy
if uncertainty about diagnosis:
-
electroneuronography (72hrs - 14 days of symptom onset)
- >90% decrease in amplitude of compound muscle action potential vs non-affected side –>
-
needle electromyography (EMG)
- if absence of voluntary motor unit potentials found
–> REFER TO NEURO team for possible nerve decompression
What investigation should be routinely conducted in pts with recent travel Hx and symptoms of Bell’s palsy?
-
serology for Borrelia burgdorferi
- (organism causing Lyme disease)
- should be negative for confirmation of Bell’s palsy
Which investigations should be ordered if:
a) primary investigation suggests alternative diagnosis?
b) neoplasm is suspected?
c) otoscopy suggests middle ear disease/facial or head trauma?
a) pure tone audiometry & tympanometry and stapedius reflex
b) MRI (gadolinium-enhanced fine-cut of facial nerve course)
c) CT head
What is the management plan for Bell’s palsy?
reducing recovery time
-
Oral corticosteroids (within 72hrs of symptoms)
- anti-inflammatory effect: reduced nerve oedema & minimised nerve insult
-
antiviral therapy
- decreased viral load & subsequent axonal & Schwann cell injury
preventing exposure keratopathy
- DAY: glasses protection (not a patch)
- DAY: artificial tears used as needed
- Overnight: ophthalmological lubricant ointment
- Overnight: lid taped closed
preventing severe facial synkinesis (compl.)
- only indicated in those w 90+% degeneration on electroneuronography (ENoG),*
- Surgical decompression of the bony fallopian canal from the internal auditory canal to the stylomastoid foramen
In which patients should caution be exercised before prescribing high dose corticosteroids?
- poorly-controlled DM
- immunodeficiency
- poorly-controlled HTN
- prior history of psychosis.
Which factors are indicators of poor prognosis for early return of function?
- complete flaccid paralysis on presentation
- older adult
- taste disturbance
- diabetes mellitus
What is the rationale behind surgical nerve decompression as a treatment for severe Bell’s palsy?
surgical decompression of the facial nerve
- removal of approx. 180 degrees of confining fallopian canal bone
- incision of epineurium from porus acousticus to stylomastoid foramen
- –> provides space for facial nerve to swell
- –> reducing progression of virally-triggered compressive neuropathy & subsequent ischaemic neural insult.
What is the criteria for patients to be considered for surgical nerve decompression as a treatment for Bell’s palsy?
- Clinically undetectable unilateral facial movement
- Facial palsy onset within 14 days
- ENoG (eEMG) performed between 72 hours and 14 days of facial palsy onset demonstrates >90% reduction in the amplitude of the compound muscle action potential (CMAP) using a supra-threshold neural stimulus as compared to the normal side
- Needle EMG confirms absence of voluntary motor unit potentials in facial musculature.
What is Bell’s phenomenon?
protective reflex in which eye globe rotates upwards + outwards with attempts at eye closure
(see image - patients’ right eye = affected)
What are the indications for an ophthalmological consulation in pts with Bell’s palsy?
- only seeing eye affected (i.e. blind in unaffected eye)
- suspicion of exposure keratitis
- decreased or absent corneal sensation.
Opthalmologists may consider:
- early upper eyelid weight placement OR
- tarsorrhaphy (eyelids are partially sewn together to narrow the eyelid opening)
for which patients?
- patients who lack Bell’s phenomenon
- prognosis for early rapid return of function is poor
Name some complications of Bells palsy
1) keratoconjunctivitis sicca (dry eye)
- due to ineffective lubricating tear film
- ineffective cornea-protective blink response
- reduced parasympathetic function to lacrimal gland
2) exposure keratopathy (damaged cornea due to increased exposure to outside environment)
* (via physical/infectious mechanisms)
~ –> ulcerative keratitis (corneal ulcer) AND blindness
3) ectropion (sagging eyelid)
- (rarely persists, only in flaccid stage)
4) contracture & synkinesis (= eye muscle moves simultaneously w other facial muscles) - due to increased neural irritability
- and aberrant regeneration of motor axons
- can be treated w botox to overactive muscle
5) Gustatory hyperlacrimation
- nasal cavity + palate: aberrant regeneration of pre-ganglionic parasympathetic fibres carried within facial nerve supplying lacrimal gland and mucosal glands (via the greater superficial petrosal nerve)
- oral cavity: “” supplying submaxillary, sublingual, and minor salivary glands
- can be treated w botox to lacrimal gland
Which parameter is the most predictive of ultimate recovery outcome from Bell’s palsy/
extent of facial palsy following complete evolution of Bell’s palsy (i.e., within 72 hours of onset)
What is the prognosis for patients with Bell’s palsy?
- present w incomplete paralysis: 94% fully recover
- present w complete paralysis:61% fully recover
- if electroneuronography (ENoG) = >95% difference between sides <14 days of symptom onset spontaneous return of (near) normal facial function (i.e., HBS I or II) = reduced by 50%
worse outcomes in those w/who are:
- pregnant
- uncontrolled HTN/DM
- old age
- taste disturbance
