Bells palsy

• Lower motor neuron weakness of the facial nerve in the absence of an identifiable cause

• Viral etiology suspected – ?inflammation from reactivation HSV or VZV  
• Facial nerve innervates lacrimal glands, salivary glands, stapedius muscle, taste fibres from anterior tongue, sensory fibres posterior ear canal and tympanic membrane

• Risk factors
  • Pregnancy, pre-eclampsia, obesity, hypertension, diabetes, URTI

• Symptoms
  • the eyebrow droops
    • forehead wrinkles of the brow are smoothed out
    • frowning and raising the eyebrows are impossible
    • if there is an UMN lesion affecting the facial nerve then the ability to wrinkle the brow is preserved; in Bell’s palsy this ability is lost
  • Unilateral facial weakness
  • Eye
    • corneal reflex
      • intact sensory component – trigeminal nerve
      • motor component is lost – facial innervation of orbicularis oculi.
    • Dryness of eye
      • Eye irritation often occurs due to lack of lubrication and constant exposure.
    • Loss of eye lid control
      • tear excessively 🡪 tears to spill freely from the eye
  • Hyperacusis
    • if the lesion of the facial nerve extends to above the point at which the branch to the stapedius muscle is given off
  • Mouth
    • mouth sags
    • Taste disturbance
    • lips cannot be pursed and whistling is impossible
    • Saliva drooling
  • unable to blow out the cheeks
• Onset/timing – Sudden but not stroke like – evolves minutes to hours

• Red flags
  • Gradual progression – suggests infectious or neoplastic
  • Underlying medical problems – previous stroke, brain tumour, cutaenous cancers face and neck, parotid tumour, head or facial trauma, recent infection
  • Diplopia, dysphagia, numbness of the face, dizziness

• Differential diagnosis
  • Bell’s palsy must be distinguished from other causes of facial palsy 
  • PERIPHERAL – nuclear – causes
    • lyme disease
      • this is more likely if the facial weakness is bilateral
      • history of tick exposure, and arthralgias
      • look for a rash 
    • otitis media
      • suppurative otitis is excluded by examining the ear
      • there is gradual onset ear pain, fever, and conductive hearing loss
    • Ramsay Hunt syndrome
      • herpes zoster may produce an acute facial weakness but is accompanied by a rash within the auricle – geniculate herpes – or on the palate, pharynx, face, neck or trunk
    • there may be a pronounced prodrome of pain
    • sarcoidosis
      • sarcoidosis affecting the parotid gland is suggested by recurrent facial palsy
      • facial weekness is often bilateral 
    • Guillain-Barré syndrome
      • facial weekness is often bilateral
    • HIV infection
      • more likely if the facial weakness is bilateral
      • look for lymphadenopathy 
    • tumours
      • cholesteatoma, parotid gland tumours 
  • CENTRAL – supranuclear causes
    • multiple sclerosis
      • multiple sclerosis should be considered if the palsy is
        • unilateral, in a young adult
        • painless
        • resolves in 2-3 weeks
      • stroke
      • tumours
        • metastases or primary brain tumours
        • history of cancer
        • look for mental status changes
      • Horner’s syndrome and IIIrd nerve palsies
        • produce a ptosis

• Examination
  • differentiate between an upper and lower motor neurone lesion
  • check that other cranial nerves are not involved
  • exclude masses in the head and neck
    • a deep lobe parotid tumour may only be identified clinically by careful examination of the oropharynx and ipsilateral tonsil to rule out asymmetry
    • erythema migrans on the limbs or trunk with a history of tick bite suggests possible Lyme disease, which may cause facial palsy 
  • Insepct ear and TM for herpes zoter infection – suggests Ramsay hunt syndrome
  • Head and neck – cancer/masses
  • Assess all cranial nerves
  • Sparing of forehead suggests central pathology – but could also be seen in a peripheral lesion of one nerve branch
  • Usually resolve spontaneously, 70% notice improvement within 3 weeks, complete recovery 3 months

• Treatment
  • Corticosteroids
    • Initiate within 72 hours of symptom onset
    • eTG – prednisone 1mg/kg up to 75mg orally for 5 days, could continue 10 days and taper down
  • Antiviral therapy
    • may have a small benefit but not clear in studies
    • Definitely needed if Ramsay hunt – consider IV antibirals
      • valacyclovir (1000 mg three times daily).S/E: nausea, vomiting and diarrhoea
  • Incomplete eye closure
    • Risk
      • foreign body
      • exposure keratitis
      • corneal ulceration
      • loss of vision
    • Wear sunglasses, lubricating eye drops/ointment
    • Tape eyelid at night
    • Immediately report any eye symptoms
  • Psychological help
    • patients with facial dysfunction suffer from depression and a reduced quality of life as a result of their appearance
    • support and counselling to cope

• Refer
  • worsening neurological findings
  • facial diplegia
  • ocular symptoms or complications
  • incomplete facial nerve recovery three months after initial symptom onset
  • Consider investigations for neoplasms for brainstem, cerebellopontine angle, parotid gland – MRI
  • Refer to opthal if incomplete eye closure, other complications If persistent could consider cosmetic