BELL’S PALSY

This is lower motor facial nerve palsy of unknown origin and should be regarded as a diagnosis of exclusion.

So to exclude other causes a good history and examination is required.

Bells palsy typically presents with:

• Rapid onset lower motor facial nerve palsy (Upper motor palsies lead to only the lower half of the face paralysed as the forehead has a bilateral control centrally)
• May report having a flu or chest infection or under a lot of stress.
• Reduced tear flow on the affected side (one of the first branches off the facial nerve)
• Hyperacusis – oversensitivity to loud noises (due to loss of control of the stapedius muscle which is the next branch off the facial)
• Loss of taste on affected side of tongue – more commonly presents with a metallic taste on that side (controlled by the corda tympani the next branch off the facial nerve, just before it leaves the temporal bone.)
• Post auricular pain

On examination you should grade the facial nerve palsy using the House and Brackmann grading system

• Grade 1 – normal facial function
• Grade 2 – you note only slight weakness – looks normal at rest and the eye can be closed with minimal effort
• Grade 3 – is much like grade 2 but every movement requires much more effort. Closing the eye can be achieved with strain.
• Grade 4 – patient is unable to close the eye and the mouth looks asymmetrical even on maximal effort
• Grade 5 – movement is only barely noticed – and there is asymmetry at rest
• Grade 6 – no movement at all – complete paralysis

You should, as a minimal, examine the course of the extra-temporal facial nerve (as parotid tumours for example can give you facial palsies – although they tend to present as partial nerve palsies.)

You should examine the ear (please see the ear examination topic for this). Look out for vesicles in the conchal bowl as this would indicate Ramsay-Hunt syndrome (zoster infection of the geniculate ganglion). Also disease of the middle ear can also affect the facial nerve so things like cholesteatoma (see link to www.chicagoear.com) may present with facial nerve palsy.

Bell’s palsy can affect any age group, although the elderly more slightly more affected.
Those with diabetes are more likely to get bell’s palsy
Those who are pregnant – particularly in the 3th trimester – and particularly those who have pre- eclampsia

Management

This is quite controversial but a safe formula would be to prescribe:

• 1mg/kg (up to 80mg) of prednisolone for 10 days (don't give aciclovir)*
• Consider Valaciclovir 500mg twice a day for 5 days(some studies have shown that many cases of bells palsy are actually caused by Herpes Simplex virus)**
• Eye care – this is extremely important! Particularly in palsies grade 4 and above the eye is over exposed and can become dry leading to corneal scarring.
• Provide artificial tears for the day time
• Lubricants / ointments for the night – this has a better lubricating effect but has the disadvantage of giving you blurred vision.
• Wear an eye shield at night (to stop the patient from rubbing the eye whilst asleep)
• Tape the eyes closed at night – to protect the corneas.

*New England Journal of Medicine. 2007 Oct 18;357(16):1598-607 'Early treatment with prednisolone or acyclovir in Bell's palsy' - the evidence from this well designed trial suggests that in patients who present within 72 hours of symptoms, prednisolone should be given but not aciclovir. More research is required to assess the effectiveness of valaciclovir in bells palsy.

**Hato N, Yamada H, Kohno H, et al. Valacyclovir and prednisolone treatment for Bell's palsy: a multicenter, randomized, placebo-controlled study. Otol Neurotol 2007;28:408-13.

Prognosis

Most patients will eventually achieve full recovery (90%+)
About 80-85% have full function after 3 months.
About 85% have some improvement within 3 weeks.
Those who have a incomplete facial palsy (House-Brackmann of 2-5) have a better chance of full and quick recovery.
The younger you are the quicker the recovery.
The more symptoms you have initially (post auricular pain, metallic taste etc.) and the more risk factors you have (diabetic, pregnant etc) the slower and worse the prognosis.

Further Reading

eMedicine - Bell's Palsy : Article by Craig H Zalvan, MD

eMedicine - Bell Palsy : Article by Michael Lambert, MD,

Wikipedia - Facial Nerve

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