Makindo Medical Notes

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

Bell's Palsy is an idiopathic, acute, unilateral lower motor neuron (LMN) facial nerve palsy. It develops quickly, usually within 72 hours, and does not progress further after that time. Gradually progressive facial palsy is not Bell's. Ear and facial pain are common in Bell's palsy and do not necessarily indicate middle ear disease.

About

• Bell's Palsy can mimic a stroke but typically affects the lower motor neuron of the facial nerve, generally unilaterally.
• Named after Sir Charles Bell (1774-1842).
• Incidence: 15-30 per 100,000 people, affecting men and women equally.

Anatomy of the VII Nerve

Aetiology

• Most cases are idiopathic, though suspected to be viral (possibly HSV or VZV).
• The nerve may become inflamed and compressed in its bony canal.
• If caused by Varicella zoster, it is called Ramsay Hunt syndrome.

Clinical Features

• Rapid onset of facial weakness, typically within hours or days.
• Facial pain around the affected ear is common.
• Affects the entire side of the face, including the forehead, eye, and mouth.
• May have altered sensation, loss of taste on the anterior two-thirds of the tongue, hyperacusis, and reduced tear production.
• Impaired corneal reflex (motor side affected).
• Bell's Sign: Eye moves up and out when attempting to close the eyelid.
• Check for vesicles (indicating Ramsay Hunt) and associated VI nerve palsy to localize the lesion to the pons if present.

Key Exclusions in Bell's Palsy

• No other neurological deficits, normal otoscopy (no vesicles), no masses in neck/parotid, and no skin/pinna/throat lesions.
• Rule out skull base fractures, Lyme disease, or middle ear infection as causes.

Clinical Examination Notes

• Although VII is primarily motor, altered sensation may occur, often reported as numbness but with preserved touch perception.
• Tests to clarify affected side:
  • Ask patient to smile/show teeth — weakened side will be slower and lower.
  • Ask patient to close eyes — the affected side will close incompletely, possibly showing Bell's sign.
  • Look for reduced forehead wrinkles on the affected side and compare volume perception over the ear (affected side may sound louder).

Differential Diagnosis

• Parotid tumor (often malignant); look for masses.
• Lyme disease (bilateral LMN VII); ask about tick bites, rash, or joint pain.
• Sarcoidosis (Heerfordt's syndrome); LMN VII, bilateral hilar lymphadenopathy.
• Guillain-Barré syndrome (bilateral LMN VII); associated with tingling in extremities.
• Stroke: Cortical stroke spares the forehead and eye; look for other neurological signs.
• Pontine stroke (brainstem): may have associated VI nerve palsy and contralateral weakness.

Investigations

• Primarily a clinical diagnosis; FBC, U&E, Glucose, ESR, and TFTs may be considered if needed.
• Imaging: CT generally unhelpful; MRI may show pontine pathology or geniculate ganglion enhancement.
• Nerve conduction/EMG: Rarely needed; may help assess nerve injury extent in later stages.

House-Brackmann Classification of Facial Nerve Function

• Grade I: Normal.
• Grade II: Mild dysfunction with minimal asymmetry, complete eye closure.
• Grade III: Moderate dysfunction; complete eye closure with effort, some mouth asymmetry.
• Grade IV: Severe dysfunction with obvious weakness, incomplete eye closure.
• Grade V: Minimal facial motion, incomplete eye closure.
• Grade VI: No facial movement.

Potential Complications

• Permanent facial paralysis, hearing loss, and synkinesis (involuntary movements).

Management

• Steroids: If symptoms started within 72 hours, give Prednisolone 1 mg/kg (or 60 mg) for 6 days with a taper over 10 days.
• Antivirals: Consider Valacyclovir or Aciclovir if viral cause is suspected.
• Eye Care: For difficulty closing the eye, use artificial tears, Lacrilube ointment at night, and consider an eye patch.
• Ramsay Hunt Syndrome: If vesicles present, treat with aciclovir 800 mg five times daily for 7 days or valaciclovir 1000 mg TDS.
• Recovery usually occurs within 3 weeks to 2-6 months.

Referral Criteria

• Uncertainty in diagnosis, recurrent or bilateral Bell's palsy.
• If the cornea is exposed, urgent ophthalmology referral is needed.
• If no improvement by one month or a serious diagnosis is suspected, refer to ENT.
• Residual paralysis after 6-9 months may need plastic surgery referral.

Prognostic Factors for Poor Recovery

• Complete palsy without recovery by three weeks, age >60, severe pain, Ramsay Hunt syndrome, hypertension, diabetes, pregnancy, and severe nerve degeneration on electrophysiology.

References

• BMJ Review on Bell's Palsy

Images and Additional Resources

• Available images and further resources