Makindo Medical Notes.com

Related Subjects: |Bell's (Facial Nerve) palsy |Ramsay Hunt syndrome |Facial nerve anatomy

Bell's Palsy is an idiopathic, acute, unilateral LMN facial nerve palsy. It develops quickly in under 72 hours (usually faster), and does NOT progress after 72 hours. A facial palsy that is gradually progressive is not Bell's. Note that ear and facial pain in Bell's palsy are relatively common, and on their own do not signify middle ear disease.

About

• A well-known stroke mimic
• Lower motor neurone weakness of facial nerve typically unilateral
• Bell's palsy is named after Sir Charles Bell (1774-1842)
• Incidence of Bell's palsy is 15 to 30 per 100,000 persons
• Equal numbers of men and women affected

Anatomy of VII nerve

Aetiology

• Most often idiopathic - suspected viral ? HSV ? VZV
• The nerve is compressed and inflamed in its bony canal
• If due to Varicella zoster called Ramsay Hunt syndrome

Clinical

• Subacute onset over days/hours of a facial palsy
• Facial pain around the ear on the affected side for a few days
• Involves complete side of face - forehead, eye, mouth
• Although a motor nerve there may be altered sensation
• Loss of sensation on anterior 2/3rds of the tongue
• Hyperacusis and decreased tear production
• Impaired corneal reflex motor side is affected
• Bell's sign - eye moves up and out when trying to close eye
• Pain and vesicles should alert one to Ramsay Hunt syndrome
• Look for a VI nerve palsy which would isolate the lesion to the pons
• There may be mild ache over the back of the head

With Bells there is no

• Additional Neurological deficit
• Otoscopy shows no vesicles, a normal eardrum and external canal
• No neck or parotid masses
• No vesicles in the skin, pinna, canal, mouth or throat
• No other causes (eg skull base fracture, Lyme disease, middle ear infection)

Clinical Notes

• Although VII is a motor nerve to the face facial sensation is commonly altered and feels numb but they will be able to appreciate touch bilaterally.
• It is not uncommon that clinicians can get confused with mild cases and often misreport the side affected. The patient may even get confused.
• There are a couple of tests that can help to clear up the picture
• Ask the patient to smile or show teeth. The angle of the mouth on the affected weakened side will be lower.
• Ask patient to close eyes and watch closely - the weak side will be slower to close and incomplete (DOK's sign) and there may be a positive Bell's sign.
• Eye closing is very rarely affected in stroke other than a ptosis with a IIIrd nerve and Horners where eye closing is not affected.
• Inspect the patient's forehead - there will be noticeably fewer wrinkles on the affected side
• Rustle fingers over-ear - the affected side may be louder

Differential

• Parotid tumour - usually malignant look for any masses or swelling
• Lyme disease (Bilateral LMN VII) History of a tick bite, rash, joint pains etc.
• Sarcoid - Heerfordt's syndrome (LMN VII), BHL etc...
• Guillain-Barré syndrome (Bilateral LMN) tingling toes and fingers
• Cortical Stroke (weak ipsilateral arm/leg/speech/visual signs) and the eye and above are not affected significantly
• Brainstem Stroke: Pontine Lesion: Associated ipsilateral VI nerve palsy, cerebellar signs, contralateral weakness

Investigation

• None may be needed as it is a clinical diagnosis. If there is uncertainty refer.
• FBC, U&E, Glucose, ESR, TFTs may be done
• CT usually unhelpful. MRI - if stroke a concern. Can show pontine pathology. There can be nerve enhancement with Bell's near the geniculate ganglion. Tumours compressing the nerve may be seen.
• Nerve conduction test/EMG: not standard. May be done in the post-acute phase to determine the extent of injury to the nerve.

House-Brackmann classification scores include the following:

• Grade I: Normal
• Grade II: Slight facial weakness or other mild dysfunction. Normal tone and symmetry at rest. Complete closure of the eye without effort. Slight asymmetry of the mouth when facial movements occur.
• Grade III: Assigned to patients dealing with moderate dysfunction; these patients generally do not display any noticeable facial weakness with synkinesis, they maintain complete eye closure and good forehead movement with effort.
• Grade IV: Assigned to patients dealing with severe dysfunction. Obvious facial weakness. Incomplete eye closure, no forehead movement, asymmetrical mouth movement, and synkinesis.
• Grade V: Assigned to patients who have little to no ability to smile, frown or make other facial expressions. The closure of the eye is incomplete, and there is no forehead movement.
• Grade VI: No facial motion

Complications may include

• Permanent facial paralysis
• Hearing loss
• Synkinesis (unwanted facial movements linked to deliberate movements)

Management

• If no infective cause and within 72 hrs of the onset of symptoms then Prednisolone 1 mg/kg or 60 mg/day for 6 days, followed by a taper, for a total of 10 days improves outcome. Consider oral Valacyclovir or Aciclovir if viral cause suspected.
• If the patient has difficulty closing the eye, an ophthalmology review should be sought via eye casualty. Also refer urgently to eye casualty if the patient develops a red eye
• Artificial tears and an eye patch may be needed too. Lacrilube ointment should be given at night, and viscotears or celluvisc drops during the daytime (lacrilube ointment is thick and viscous and may interfere with vision during the daytime).
• If Ramsay-Hunt syndrome is suspected on the basis of vesicles being present in any of the ear canal/pinna/face / mouth/throat, then aciclovir 800 mg five times for 7 days should be given. (equivalent to valaciclovir 1000 mg TDS 7 days)
• There is usually recovery over 3 weeks to 2-6 months

Refer

• Any doubt regarding the diagnosis.
• Recurrent Bell's palsy.
• Bilateral Bell's palsy.
• If the cornea remains exposed after attempting to close the eyelid, refer urgently to ophthalmology.
• If the paralysis shows no sign of improvement after 1 month, or there is suspicion of a serious underlying diagnosis (e.g. cholesteatoma, parotid tumour , malignant otitis externa), refer urgently to ENT.
• If there is residual paralysis after 6-9 months, consider referral to a plastic surgeon with a special interest in facial reconstructive surgery.

Poorer prognosis

• Complete facial palsy with no recovery by three weeks
• Age over 60 years, Severe pain
• Ramsay Hunt syndrome (herpes zoster virus)
• Hypertension, diabetes, pregnancy
• Severe degeneration of the facial nerve shown by electrophysiological testing

References

• BMJ review on the subject

Images online

• Images available online