Bell's Palsy

See Also

Definitions

Bell's Palsy (Facial Nerve Palsy)
1. Idiopathic, acute Facial Nerve Paralysis

Background
History

Named for Sir Charles Bell (1774-1842) who first described the syndrome

Epidemiology

Incidence: 15-30 per 100,000 per year (45,000 per year in U.S.)
No gender predominance
Incidence peaks at age 40-49 years

Pathophysiology

Facial Nerve inflammation typically at Geniculate Ganglion (risk of ischemia, demyelination)
Associated with Herpesvirus infection in 30% of cases

Risk Factors

Diabetes Mellitus (comorbid in 10% of cases)
Pregnancy (associated with 3 fold increased risk)
Herpesvirus infection (comorbid in 30% of cases)

History
Red Flags suggestive of other Facial Nerve Paralysis Cause

Gradual onset over >2 weeks
1. Suggests mass lesion
Forehead not involved
1. Suggests Central Nervous System cause (supranuclear lesion)
2. Facial Nerve motor nucleus is divided
  1. Dorsal aspect (forehead innervation) and ventral aspect (lower facial innervation)
  2. Both sides of the brain provide input to the dorsal aspect (forehead)
    1. Hence lack of forehead involvement implies an Upper Motor Neuron Lesion
  3. Only one side of the brain provides input to the ventral aspect (lower face)
Bilateral involvement
1. Suggests autoimmune Polyneuropathy
2. Lyme Disease
Recent new medications (e.g. Influenza Vaccine)
Lyme Disease Risk Factors (Tick Bite, endemic Lyme Disease region during peak season)
1. Lyme Disease
Fever
1. Consider infectious cause such as Otitis Media
Rash
1. Vesicular rash (Herpes Zoster, Ramsay Hunt Syndrome)
2. Erythema Migrans (Lyme Disease)
Hearing Loss and Vestibular Symptoms or Ataxia
1. Acoustic Neuroma

Exam

Head and neck
1. External Ear and ear canal (e.g. Otitis Externa, Herpes Zoster, Ramsay Hunt Syndrome)
2. Tympanic Membrane (e.g. Otitis Media)
3. Mouth and pharynx (e.g. Herpes Simplex Virus)
4. Parotid Gland
Neurologic Exam
1. Perform complete Neurologic Exam including gait
2. Cranial Nerve Exam
  1. Test Cranial Nerve 7 bilaterally on lower face and forehead
3. Extremity Motor Exam and Sensory Exam
Skin
1. Vesicular rash (Herpes Zoster, Ramsay Hunt Syndrome)
2. Erythema Migrans (Lyme Disease)

Symptoms

Idiopathic Facial Nerve Paralysis
1. Hypoesthesia or dysesthesia (80%)
  1. Glossopharyngeal Nerve dysfunction
  2. Trigeminal Nerve dysfunction
2. Facial or retroauricular pain (60%)
3. Dysgeusia (57%)
4. Hyperacusis (30%)
5. Vagal nerve motor weakness (20%)
6. Decreased Lacrimation (17%)
7. Trigeminal Nerve motor weakness (3%)
8. Synkinesis (e.g. mouth twitching while blinking, or winking while smiling)
References
1. Adour (1982) N Engl J Med 307: 348-51 [PubMed]

Signs
General

Preserved facial Sensation
Mouth and nasolabial changes
1. Loss of facial creases and nasolabial fold
2. Corner of mouth droops
Eye changes
1. No closure or decreased closure of upper Eyelid
2. Lower Eyelid sag
3. Decreased tear production
No furrow over forehead (forehead appears flattened)
1. Critical to recognize when the forehead and Eyelid are not involved
2. Lack of forehead and Eyelid involvement suggests an Upper Motor Neuron Lesion such as a CVA

Signs
Facial Nerve Grading (House-Brackman)

Grade 1: Normal Facial Nerve Function
Grade 2: Mild Facial Nerve Dysfunction
1. Gross
  1. Slight weakness on close examination
  2. Synkinesis slight
2. Rest: Normal symmetry and tone
3. Motor Exam
  1. Forehead: Moderate to good function
  2. Eyes: Complete closure with minimum effort
  3. Mouth: Slight asymmetry
Grade 3: Moderate Facial Nerve Dysfunction
1. Gross:
  1. Obvious difference between sides (not disfiguring)
  2. Synkinesis noticeable
2. Rest: Normal symmetry and tone
3. Motor Exam
  1. Forehead: slight to Moderate movement
  2. Eyes: Complete closure with effort
  3. Mouth: Slightly weak with maximal effort
Grade 4: Moderately Severe Facial Nerve Dysfunction
1. Gross
  1. Obvious weakness
  2. Disfiguring asymmetry
2. Rest: Normal symmetry and tone
3. Motor Exam
  1. Forehead: No motor function
  2. Eyes: Incomplete closure
  3. Mouth: Asymmetric with maximal effort
Grade 5: Severe Facial Nerve Dysfunction
1. Gross: Barely perceptible motion
2. Rest: Asymmetry
3. Motor Exam
  1. Forehead: No motor function
  2. Eyes: Incomplete closure
  3. Mouth: Slight movement
Grade 6: Total Facial Nerve Paralysis
References
1. House (1985) Otolaryngol Head Neck Surg 93:146-7 [PubMed]

Differential Diagnosis

See Facial Nerve Paralysis Causes

Labs

Labs are not indicated in isolated peripheral Facial Nerve Paralysis
Serum Glucose is not routinely recommended
1. Diabetes Mellitus does not cause Bell's Palsy, and is simply a predisposing factor
Lyme Antibody titer is not routinely recommended
1. Lyme peripheral facial palsy is almost always associated with other findings (e.g. Arthritis, facial swelling, rash)
2. Isolated Facial Nerve Palsy is not typically due to Lyme Disease
3. However, consider lymes test with risk factors
  1. Bilateral Facial Nerve involvement (high risk, treat as Lyme Disease while testing)
  2. Known recent deer Tick Bite
  3. Erythema Migrans (diagnostic without Lyme Titer)
  4. Peak season in endemic Lyme Disease region
4. References
  1. Kuiper (1992) Arch Neurol 49(9): 940-3 [PubMed]

Imaging
MRI Head

Benefits
1. MRI Identifies central causes (Schwannoma, Hemangioma, meningioma and Cholesteatoma)
2. MRI offers prognostic information based on nerve contrast enhancement
Indications
1. Suspected central cause (see Red Flags above)
2. Persistent or progressive peripheral Facial Nerve Palsy lasting >2 months
3. Facial twitching or spasm

Management
Loss of Blink Reflex

Rewetting the eye
1. Frequent use of preservative-free artificial tears (every 15 to 30 minutes)
2. Refresh PM ointment six times daily
Protective glasses with side pieces
1. Use in outdoors, drafty, dusty areas
2. Alternatively can use eye shield or cup
Avoid grinding, sanding, or sawing
At night:
1. Apply bland ointment (Refresh PM, Lacri-Lube)
2. Tape eye shut
Ophthalmology Consultation indicated for incomplete Eyelid closure persisting for weeks
1. Risk of permanent ocular injury from drying

Management
Corticosteroids and Antivirals

Approach
1. Start Corticosteroid within 72 hours of onset
2. Antiviral may be considered in moderate to severe cases (House-Brackman Grade 4 and above)
3. Consider Lyme Disease management if suggested by history or exam
  1. Doxycycline (preferred) 100 mg bid or Amoxicillin 500 mg tid for 14-21 days
High dose Corticosteroids: Prednisone or Prednisolone (primary intervention)
1. Adult: 60-80 mg orally daily for 7 days
2. Child: 2 mg/kg/day (up to adult dosing) for 7 days
3. Salinas (2010) Cochrane Database Syst Rev (3):CD001942 +PMID:20238317 [PubMed]
Antiviral agents (optional)
1. Mechanism
  1. Based on reactivated HSV hypothesis
2. Indications
  1. Findings consistent with Herpes Zoster, herpes simplex or Ramsay Hunt Syndrome (e.g. vesicular rash)
  2. Antiviral may be considered in moderate to severe cases (House-Brackman Grade 4 and above)
3. Efficacy of empiric antiviral use (excluding cases of herpetic, vesicular rashes which should be treated)
  1. Original studies showed synergistic benefit with antivirals in combination with Corticosteroids
    1. More recent studies show primary improvement with Corticosteroids
    2. Only marginal added benefit with antivirals
  2. Reasonable to offer antivirals in moderate to severe cases
    1. However patients should be counseled on low efficacy of antivirals
4. Agents
  1. Acyclovir
    1. Adult: 400 mg five times per day for 7 days
    2. Child (>2 years): 80 mg/kg daily (max: 3200 mg/day) divided every 6 hours for 5 days
  2. Valacyclovir
    1. Age >12 years: 1 gram orally three times daily for 7 days
5. References

Management
Associated Conditions

Otitis Media or Mastoiditis Complications
1. IV antibiotics
2. Otolaryngology Consultation for possible wide incision of Tympanic Membrane
Herpes Zoster Oticus (Ramsay Hunt Syndrome)
1. See Herpes Zoster for antiviral agents
2. May be associated with Tinnitus and Hearing Loss
3. High dose Corticosteroids (1 mg/kg/day)
  1. Avoid in Diabetes Mellitus, peptic ulcer, Glaucoma

Management
Referral Indications

Otitis Media complications
Mastoiditis complications
Signs of secondary cause
1. Intracranial lesion or nerve impingement
Incomplete Eyelid closure persisting for weeks
1. Risk of permanent ocular injury from drying
2. Referral to ophthalmology for management beyond artificial tears
Other procedure referrals not routinely recommended
1. Facial Nerve decompression surgery (may rarely be indicated)
2. Physical Therapy (no evidence of benefit in Bell's Palsy)

Prognosis
Factors associated with poor prognosis

Worse Prognosis with time needed for recovery
1. No recovery by 3 weeks suggests worse prognosis (15% of cases)
2. Further recovery occurs over 3-5 months
Hyperacusis
Diabetes Mellitus
Hypertension
Pregnancy
Facial Nerve with severe degeneration by EMG
Decreased tearing
Age over 60 years
Ramsay Hunt Syndrome (Herpes Zoster Virus)
Severe pain
1. Aural pain
2. Anterior facial pain
3. Radicular pain

Complications

Corneal Ulceration
Permanent Eyelid weakness
Permanent facial asymmetry

Prognosis

Early recovery (85%) within 3 weeks
Prolonged recovery (15%) over 3-5 months
1. Slight residual deficit: 12%
2. Mild residual deficit: 13%
3. Severe residual deficit: 4%
  1. Facial weakness
  2. Contracture or spasm
Recurrence: 8% of cases
1. Higher risk of recurrence in Diabetes Mellitus

Course

Maximal weakness at 3-7 days after onset
Most cases (85%) improve within 3 weeks even without treatment
1. Additional improvement may require up to 5 months
2. Prolonged recovery duration required for nerve regeneration

References

Herbert et al in Herbert (2015) EM:Rap 15(11): 3-4
Zalvan (1999) Consultant 39(1):39-48
Zvonar and Welsh (2021) Crit Dec Emerg Med 35(2): 25
Albers (2014) Am Fam Physician 89(3): 209-12 [PubMed]
Gilden (2004) N Engl J Med 351:1323-31 [PubMed]
Holland (2004) BMJ 329:553-7 [PubMed]
Tiemstra (2007) Am Fam Physician 76:997-1002 [PubMed]