Facial Nerve Palsy

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Introduction

  • Facial (nerve) palsy is a neurological condition in which the function of the facial nerve(cranial nerve VII) is partially or completely lost.
  • It is often idiopathic but in some cases, specific causes such as infections or trauma can be identified.

Types of Facial nerve Palsy

  • Central or Upper
Lesions occur between cortex and nuclei in the brainstem.
  • Peripheral or Lower
occurs between nuclei in the brainstem and peripheral organs.

Etiology

  • The most common cause of Facial nerve palsy is Bell’s Palsy.
  • Idiopathic disease is the second most common cause
  • Other causes of sudden one sided facial nerve paralysis include a traumatic head injury, stroke, viral infection such as herpes simplex or herpes zoster
  • Rare cause includes Lyme disease and Sarcoidosis

Pathophysiology

  • The facial muscles are innervated peripherally (infra nuclear innervation) by the ipsilateral 7th cranial nerve and centrally (supra nuclear innervation) by the contralateral cerebral cortex.
  • Central innervation tends to be bilateral for the upper face (e.g, forehead muscles) and unilateral for the lower face.
  • Peripheral lesions (facial nerve palsy) tend to affect the upper face more than central lesions (e.g, stroke) do.
  • Central and peripheral lesions tend to paralyze the lower face.
 

Figure 1: Showing distribution of facial muscles paralysis following upper motor and lower motor facial nerve palsy

 
notion image
 

Table 1: Differences between the lesions of the Facial Nerve

Differences between the lesions of the Facial Nerve
Upper motor neurone lesion
Lower motor neurone lesion
Paralysis of the muscles of lower and upper halves of the face of the same side of the lesion
Lesion to the facial motor nucleus
Associated with hemiplegia on the opposite side of paralysis
Inability to raise eyebrow with absence of wrinkles on the affected side
Inability to close eye widened palpebral fissure

Sign and symptoms

  • pain behind the ear
  • paresis
  • affected side becomes flat and expressionless
  • ability to wrinkle the forehead, blink and grimace is limited or absent
  • in severe cases, peripheral fissure widens and the eye does not close
  • conjunctiva irritation
  • corneal drying

Clinical Examination

  • Sensory examination is normal.
  • External auditory canal and a small patch behind the ear (over the mastoid) may be painful to the touch.
  • If the nerve lesion is proximal to the geniculate ganglion, salivation, taste, and lacrimation may be impaired, and hyperacusis may be present.

Diagnosis

Clinical Evaluation
  • Chest x-ray or CT .
  • Serum angiotensin-converting enzyme (ACE) levels to check for sarcoidosis.
  • Serum glucose is measured to check for diabetes
  • MRI if onset was gradual or other neurologic deficits are present.
  • Diagnosis is mainly clinical.

Prognosis

  • In idiopathic facial nerve palsy, the extent of nerve damage determines outcome.
  • If some function remains, full recovery typically occurs within several months.
  • Nerve conduction studies and electromyography are done to help predict outcome.
  • The likelihood of complete recovery after total paralysis is 90% if nerve branches in the face retain normal excitability to supramaximal electrical stimulation and is only about 20% if electrical excitability is absent.
  • Chronic disuse of the facial muscles may lead to contractures and may result in permanent cosmetic damage in 10%.

Treatment

  • Corneal drying must be prevented by frequent use of
    • Natural tears
    • isotonic saline or methylcellulose drops intermittent use of tape or a patch to help close the eye. Tarsorrhaphy is occasionally required.
  • In idiopathic facial nerve palsy (Bells Palsy),
    • Corticosteroids, if begun within 48 hours after onset, result in faster and more complete recovery.
      • Prednisone 60 to 80 mg orally once a day is given for 1 week, then decreased gradually over the 2nd week.
    • Antiviral drugs effective against herpes simplex virus
      • (eg, valacyclovir 1 g orally 3 times a day for 7 to 10 days, famciclovir 500 mg orally 3 times a day for 5 to 10 days, acyclovir 400 mg orally 5 times a day for 10 days).
  • F/U recommendations
    • If does not show improvement in 57 days follow up with PCP right away
  • Recent data suggest that antiviral drugs provide no benefit.
 
🔗
Refer to SOAP note on Bells Palsy
 

Continuity of Care

  • Inpatient and Outpatient Neurology Follow up
  • Outpatient PCP Follow up
  • Eye patch for sleep
  • Artifical tears as needed
  • Order therapies as indicated (Physical, occupational &/or Speech)

Bibliography

 
 
 
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