Bell’s Palsy

Shout out to my sisters- who don’t actually read this, but shout out all the same- for letting me borrow them for examination practice this evening. I just did a cardio, resp, abdo, upper limb, lower limb, cranial nerves, breast and thyroid exam between the pair of them. I think (actually, they made it quite clear) everyone in the living room was tired of hearing the same introduction over and over again.

Hello, my name is ——- —– and I’m a third year medical student. Can I just confirm your name and date of birth please? Nice to meet you —-. Is it ok if I call you —-. And how old does that make you? Brilliant! So, I’ve been asked by the doctors to come and examine your heart today and what that is going to involve is just me having a feel of your chest and a listen to your heart. Will that be ok? Brilliant! So, for the purpose of this examination, I’m going to need you to be undressed from the waist up; so, if you could take your top off and any undergarments behind the curtain and let me know when you are ready to start, whilst I just wash my hands. The examiner will act as our chaperone, but would you like anyone else in the room with you? Before, we begin, are you in any pain today?

That’s my beginning spiel for my examinations. Over and over again.

Hello by name is —- ….


Bell’s Palsy

Definition: idiopathic lower motor neuron facial nerve palsy (Cranial Nerve VII)

Aetiology/ risk factors:

-Idiopathic

-60% are preceded by an upper respiratory tract infection, suggesting a viral or post-viral aetiology.

-There are known causes of facial nerve palsy but these do not qualify as Bell’s Palsy (70% of cases).

Other causes of facial nerve palsy:

Ramsay Hunt syndrome = when latent varicella zoster virus reactivates in geniculate ganglion of the facial nerve and presents with painful vesicular rash on the auditory canal +/- on the drum, pinna, tongue palate or iris, with ipsilateral facial palsy, loss of taste, vertigo, tinnitus, deafness, dry mouth and eyes. Treat with aciclovir + prednisolone, ideally within first 72h.

Lyme disease (Borrelia sp.)

-Meningitis (e.g. fungal)

-TB, viruses (HIV, polio)

Mycoplasma (rare)

-Brainstem lesions (stroke, tumour, MS)

Cerebello-pontine angle (acoustic neuroma, meningioma)

Systemic disease (diabetes, sarcoidosis, Guillain-Barre [often bilateral])

Orofacial granulomatosis, parotid tumours, otitis media or cholesteatoma,

Trauma to skull base, diving (barotrauma + temporal bone pneumocele)

-Intracranial hypotension

Epidemiology: incidence = 15-40/100,000/yr

-sex ratio equal

-3x risk during pregnancy

-5x risk in diabetes

Symptoms:

Specific(ish) to Bell’s palsy

-abrupt onset (e.g. overnight or after a nap) with complete unilateral facial weakness at 24-72h

-ipsilateral numbness or pain around the ear (facial nerve supplies some somatic sensation to the outer ear)

-50% experience facial, neck or ear pain or numbness

decrease taste sensation i.e. ageusia- uncommon (facial nerve supplies taste sensation to the anterior 2/3rds of the tongue)

hypersensitivity to sounds i.e. hyperacusis (facial nerve supplies stapedius muscle in the middle ear)

Any facial nerve palsy

unilateral sagging of 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 watery or dry eye, ectropion (sagging and turning-out of lower lid), injury from foreign bodies, or conjunctivitis

Image result for eyelid ectropion bell's palsy

Note the ectropion

Signs:

-ipsilateral facial droop, including the forehead

In stroke, the forehead is spared (they can still raise their eyebrows, wrinkle their forehead and close their eyes forcefully), as there is dual innervation from both cerebral hemispheres.

Lower motor neurone weakness of facial muscles

-unable to wrinkle forehead (frontalis muscle) or close eye forcefully (obturator occuli muscle)

-unable to blow out their cheek (buccinator muscle)

Image result for bell's palsy

Image result for bell's palsy

-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.

Consider other pathologies if: bilateral symptoms, upper motor neurone signs, other cranial neuropathies (e.g. V or XII, but also seen in 8% of Bell’s), limb weakness, and rashes.

Examine ear to exclude other pathologies e.g. otitis media, Ramsay Hunt syndrome.

Investigations:

-Bell’s palsy is partly a diagnosis of exclusion

Bloods- ESR, glucose (diabetes?)

Borrelia antibidoes (Lyme disease- clinically indistinguishable from Bell’s)

VZV antibodies (Ramsay Hunt syndrome)

MRI- space-occupying lesions, stroke, MS

Lumbar puncture- check CSF for infections (rarely done)

Nerve conduction studies (EMG)- at 2 weeks, predict slow recovery by showing axon degeneration, but don’t influence treatment, so not routinely done.

Management:

PREDNISOLONE– if given within 72h of onset, speeds recovery, with 95% making full recovery, perhaps by reducing axonal oedema. Corticosteroids are still also widely used if presenting 72h after onset.

Protect eye- dark glasses, artificial tears (e.g. hypromellose) if evidence of drying

-encourage regular eyelid closure by pulling down the lid by hand

-use tape to close the eye at night

Surgery:

If eye closure is a long-term problem (lagophthalmos)

= Lid loading procedure to upper eyelid (e.g. with gold)

If ectropion severe = lateral tarsorrhaphy (partial lid-to-lid suturing)

Image result for lateral tarsorrhaphy

If no recovery within 1yr = plastic surgery to help lid closure and to straighten drooping face can be tried

Botulinum toxin– can augment facial symmetry

Some low quality evidence for tailored facial exercises

Complications:

-Corneal ulcers, eye infection

Aberrant reconnections upon axonal recovery leading to synkinesis- involuntary muscle movements accompanying voluntary movements.

e.g. eye blinking causes synchronous upturning of mouth

eating stimulates unilateral lacrimation (misconnection of parasympathetic fibres = gustolacrimal reflex/ crocodile tears) –intra-lacrimal gland botulinum toxin may help

Prognosis:

-Incomplete paralysis without axonal degeneration = usually recovers completely within a few weeks.

-Complete paralysis = ∼ 80% make a full spontaneous recovery (within 2-12 weeks)

∼ 15% have axonal degeneration, delayed recovery starting after ∼ 3 months and may be complicated by aberrant reconnections

References: Cheese & Onion, Rapid Medicine
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