Overview

This is weakness or paralysis of the facial muscles due to pathology of the facial nerve.

Course of the facial nerve

Branches of the facial nerve

For easy understanding you can revisit the distribution of these branches to understand the clinical presentation.

Functions of the facial nerve

Causes of facial nerve palsy by anatomic region

• Patient History
  • How long has the paralysis been present?
  • Was the onset sudden or slowly progressive?
  • Does it affect all nerve distribution or only part of the face?
  • Associated symptoms: ear pain, fever, preceding viral illness, vascular symptoms (stroke or TIA), trauma, parotid mass
• Physical examination
  • Full head and neck examination (including ears)
  • Palpation of the parotid gland and face for masses
  • Cranial nerve examination (emphasis on facial nerve and facial muscle function): wrinkling of the forehead, keep eyes closed against resistance to opening, smile to show teeth, and frown
• Clinical tests
  • Blink test – tapping on the patient’s labella should stimulate blinking. Palsy will prevent that
  • Schirmer test – testing for lacrimation using blotting paper
  • Stapedial test – sensitivity to loud sounds. Done using tympanometry
  • Salivary test – salivation rate is assessed from a submandibular duct following stimulation with a 6% citric acid solution.
  • Taste test – using salt sweet, sour, and bitter tastes along the lateral aspects of the anterior two-thirds of the tongue.
• Investigations
  • Nerve conduction studies
  • Complete Blood Count
  • C-reactive protein
  • U/E/Cs
  • VZV antibody titres
  • Immunoglobulin titres (elevated in Lyme disease)
  • Imaging studies: Ultrasound, CT or MRI
  • Audiogram if there is hearing loss
  • Imaging studies (CT-scan, MRI): for trauma or malignancy
• Conservative treatment
  • Eye care: use of artificial tears, taping the eye closed as night
  • Facial muscle therapy and massage
• Medical treatment
  • Bell’s palsy: 50mg Prednisolone for 10 days, analgesia
  • Ramsay Hunt syndrome: steroids, analgesia, antivirals (acyclovir)
  • Treat ear infections appropriately
• Surgical treatment
  • Facial nerve decompression
  • Facial nerve repair and grafting
• Poor prognostic factors
  • Age >50 years
  • Complete palsy
  • Loss of acoustic reflex
  • Ramsay Hunt Syndrome
  • Poor electrophysiological test results
  • No signs of recovery after three weeks of treatment
  • Associated comorbidites such as hypertension, diabetes, pregnancy
• Complications
  • Exposure keratitis
  • Disfigurement
  • Hemifacial spasm
  • Synkinesis – voluntary movement followed by involuntary movement
• Bell’s palsy
  • Idiopathic cause of facial palsy. Presents as a unilateral lower motor neuron lesion.
  • Risk factors include: Viral infection (HSV, CMV, EBV), diabetes mellitus, pregnancy
  • Seen in 70% of cases. Should be a diagnosis of exclusion.
• Trauma
  • Can be accidental or secondary to iatrogenic injury during surgery of surrounding structures.
  • Fractures of the petrous part of the temporal bone should alert one to the possibility of a palsy. Associated symptoms include: battles sign, nystagmus, hemotympanum.
  • Facial wounds transecting the nerve.
  • Seen in 10-23% of cases
• Infection
  • Viral (4.5%- 7%)
    • Herpes zoster infection of the geniculate ganglion (Ramsay Hunt syndrome) causing facial paralysis as well as vesicular eruptions in the ear and soft palate due to CN IX involvement.
    • Vertigo may be present due to CN VIII
  • Bacterial
    • Acute otitis media
    • Meningitis
    • Cholesteatoma
    • Necrotising otitis externa
    • Lyme disease
• Neoplasia (2.2%-5%)
  • An insidious onset of paralysis should alert you to malignant causes:
    • Acoustic neuroma
    • Parotid malignancies
    • Meningioma
    • Arachnoid cysts
    • Pontile tumors
    • Facial neuroma
    • Metastatic lesions
• Special considerations Facial nerve palsy in children Can be acquired (similar causes as mentioned above) or congenital:
  • Traumatic birth – forced delivery (causing facial injury), CS, high BWT, prematurity
  • Syndromic causes – craniofacial abnormalities such as Arnold Chiari malformations
  • Genetic causes – hereditary myopathies such as myasthenia gravis
  Bilateral facial palsy Seen in systemic disease:
  • Lyme disease
  • Guillan Barre syndrome
  • Diabetes
  • Sarcoidosis

Another way of classifying :

• Upper motor neuron lesion (forehead sparing) – stroke, subdural hematoma, multiple sclerosis, neoplasms
• Lower motor neuron lesion (forehead paralysis) – infective causes, trauma, idiopathic, neoplasms

Clinical presentation

Generally:

• Facial muscle weakness and paralysis
  • Unable to close eyes, raise eyebrows, smile, show teeth, puff cheeks
• Hyperacusis
• Metallic taste on tongue
• Reduced lacrimation

Additional symptoms:

• Prodromal viral symptoms
• Vesicular eruptions in ear and soft palate
• Otalgia, hearing loss, otorrhea, tinnitus
• Masses – malignancy

House Brackman grading system – Normal Function to complete paralysis