Bell's palsy

Background
Bilateral course of facial nerve. Note that the forehead muscles receive innervation from both hemispheres of the brain, which is why there is forehead sparing for stroke but not Bell's palsy (or other peripheral facial nerve injury).
  • Dysfunction of peripheral cranial nerve VII of unknown cause due to Inflammation at geniculate ganglion [1]
  • Maximal clinical weakness around 3 weeks; at least partial recovery by 6 months
  • Always test CN VI function (should be normal) to rule-out CVA

Clinical Features
Right-sided peripheral facial nerve palsy with inability to wrinkle the forehead and nose, unequal lid fissures, and inability to lift the corner of the mouth.
A person attempting to show his teeth and raise his eyebrows with Bell's palsy on his right side; notice how the forehead is NOT spared).
  • Acute onset (over hours) of unilateral facial paralysis
    • No forehead sparing
  • Inability to raise eyebrow on affected side
  • Drooping of angle of the mouth
  • Incomplete closure of the eyelids on the affected side
    • Can lead to corneal exposure keratitis

Associated Symptoms
  • Alterations in taste
  • Hyperacusis
  • Inability to produce tears
  • Subjective feeling of facial numbness without objective findings
  • Retroauricular pain

Differential Diagnosis

Facial paralysis
  • Bell's Palsy
  • CVA
  • Trigeminal neuralgia
  • Tick paralysis
    • Lyme Disease
  • Herpes zoster oticus (Ramsay Hunt syndrome)
  • CNS tumor
    • Acoustic neuroma or other cerebellopontine angle lesions
    • Meningioma
    • Cerebellar pontine angle
    • Facial nerve schwannoma
    • Parotid
    • Sarcoma
  • Anesthesia nerve blocks
  • Cerebral Aneurysms (vertebral, basilar, or carotid)

Others

Evaluation
  • Clinical diagnosis
  • Clinicians should NOT obtain routine laboratory testing or diagnostic imaging in patients with new-onset Bell's palsy (Level C)[2]

Management

Eye Protection
  • Cornea eye protection (Level X)[2]
    • Artificial tears qhr while patient is awake
    • Ophthalmic ointment at night
    • Eye should be taped shut at night
    • Protective glasses or goggles

Steroids

Should be started within 72hrs of symptom onset[3]

Antivirals

Most likely no added benefit when combined with steroids.[6] However also little harm associated with antivirals especially in patients with normal renal function[5]

Antibiotics
  • Consider empiric doxycycline if high index of suspicion for Lyme based on clinical presentation or lab data

Disposition
  • Discharge with ophtho follow up for monitoring of the affected cornea
  • Refer to a facial nerve specialist for:[2]
    • New or worsening neurologic findings at any point
    • Ocular symptoms developing at any point
    • Incomplete facial recovery 3 months after initial symptom onset

Prognosis
  • Most patients recover completely, although some have permament disfiguring facial weakness[7]
    • 71% of untreated patients recover completely
    • An additional 13% of untreated patients achieve near-normal function (a total of 84% achieve normal or near-normal function even without treatment)

Poor Prognostic Indicators

Any one of the following[8]

  • Older age
  • Hypertension
  • Impairment of taste
  • Pain other than in the ear
  • Complete facial weakness

See Also

References
  1. Greco A. et al. Bell's palsy and autoimmunity. Autoimmun Rev. 2012;12 622-627
  2. Baugh RF, et al. Clinical practice guideline: Bell's palsy. Otolaryngol Head Neck Surg. 2013 Nov;149(3 Suppl):S1-S27.
  3. Vargish L. For Bell’s palsy, start steroids early; no need for an antiviral. J Fam Pract. Jan 2008; 57(1): 22–25http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3183838/pdf/JFP-57-22.pdf
  4. UpToDate. Bell's Palsy Prognosis and Treatment. March, 2014
  5. Gronseth GS, Paduga R. Evidence-based guideline update: Steroids and antivirals for Bell palsy: Report of the Guideline Development Subcommittee of the American Academy of Neurology. Neurology. 2012Full Text
  6. Lockhart et al. Cochrane Database Syst Rev. 2009 Oct 7;(4):CD001869.
  7. Peitersen E. The natrual history of Bell's palsy. Am J Otol 1982;4:107-111.
  8. Gilden. Bell's Palsy. N Engl J Med 2004; 351:1323-1331
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