What is the management and treatment of Bell's palsy, a condition affecting the seventh cranial nerve (CN VII), in adults?

Bell's Palsy: Cranial Nerve VII Management

What is Bell's Palsy?

Bell's palsy is an acute unilateral facial nerve (CN VII) paralysis or paresis with onset in less than 72 hours without an identifiable cause, affecting the facial muscles including the forehead. 1, 2

• The condition results from facial nerve inflammation and edema, with a suspected viral etiology, though the exact mechanism remains unknown 2
• Annual incidence is 20-30 per 100,000 population, affecting all ages but most common in those 15-45 years old 2, 3
• Higher risk in patients with diabetes, upper respiratory infections, pregnancy, obesity, and compromised immune systems 2

Clinical Presentation and Physical Examination

The hallmark finding is unilateral facial weakness involving the forehead, distinguishing it from central causes of facial weakness which spare forehead function. 1, 4

Key examination findings include:

• Inability to raise eyebrow on affected side 1
• Incomplete eye closure (lagophthalmos) with risk of corneal exposure 1
• Flattening of nasolabial fold and drooping corner of mouth 5
• Inability to smile, puff cheeks, or wrinkle forehead on affected side 1

Associated symptoms:

• Ipsilateral ear or facial pain 1
• Hyperacusis (increased sound sensitivity) 1
• Taste disturbance on anterior two-thirds of tongue 1
• Dry eye and mouth from autonomic dysfunction 1

Use the House-Brackmann grading system (grades 1-6) to assess severity, with grade 1 being normal function and grade 6 being complete paralysis. 1

Diagnosis

Bell's palsy is a diagnosis of exclusion requiring careful elimination of other causes through thorough history and physical examination. 1, 2

When Imaging is NOT Needed

Routine laboratory testing and diagnostic imaging are NOT recommended for typical Bell's palsy presentation. 1

Red Flags Requiring Imaging (MRI with and without contrast)

• Symptoms atypical, recurrent, or persisting >2-4 months without improvement 6, 1
• Second paralysis on same side 1
• Isolated branch paralysis (not affecting entire hemiface) 1
• Other cranial nerve involvement 1
• Progressive weakness beyond 3 weeks 1
• Bilateral facial weakness 1

First-Line Treatment: Oral Corticosteroids

Prescribe oral corticosteroids within 72 hours of symptom onset for patients 16 years and older—this is the only proven effective treatment. 1, 2

Recommended Regimens

• Prednisolone 50 mg daily for 10 days 1
• OR Prednisone 60 mg daily for 5 days followed by 5-day taper 1

Evidence Supporting Steroids

• 83% recovery at 3 months with prednisolone vs 63.6% with placebo 1
• 94.4% recovery at 9 months with prednisolone vs 81.6% with placebo 1

Treatment beyond 72 hours has no proven benefit—do not delay. 1

Antiviral Therapy

Antiviral monotherapy should NEVER be prescribed for Bell's palsy—it is ineffective alone. 1, 4

Optional Combination Therapy

May offer oral antiviral therapy IN ADDITION to oral corticosteroids within 72 hours of symptom onset, though the added benefit is small. 1, 4

Antiviral options:

• Valacyclovir 1 g three times daily for 7 days 4
• OR Acyclovir 400 mg five times daily for 10 days 1, 4

Evidence shows combination therapy may reduce synkinesis rates (96.5% complete recovery vs 89.7% with steroids alone), but benefit is minimal 1, 4

Eye Protection: Critical for Preventing Corneal Damage

Implement eye protection immediately for all patients with impaired eye closure—this is mandatory to prevent permanent corneal damage. 1

Daytime Protection

• Lubricating ophthalmic drops every 1-2 hours while awake 1
• Sunglasses outdoors to protect against wind and foreign particles 1

Nighttime Protection

• Ophthalmic ointment at bedtime for sustained moisture retention 1
• Eye taping or patching with careful instruction on proper technique to avoid corneal abrasion 1
• Moisture chambers using polyethylene covers for severe cases 1

Urgent Ophthalmology Referral Needed For:

• Severe impairment with complete inability to close eye 1
• Eye pain, vision changes, redness, discharge, or foreign body sensation 1
• Signs of corneal exposure or damage 1

Electrodiagnostic Testing

Offer electrodiagnostic testing (ENoG and EMG) to patients with complete facial paralysis, but NOT to those with incomplete paralysis. 1

• Testing most reliable when performed 3-14 days post-onset 1
• Greater than 10% nerve response amplitude compared to unaffected side indicates excellent prognosis 1
• Less than 10% function carries up to 50% risk of incomplete recovery 1

Testing before 7 days or after 14-21 days provides unreliable prognostic information due to ongoing Wallerian degeneration. 1

Prognosis and Recovery Timeline

Most patients begin showing recovery within 2-3 weeks, with complete recovery typically occurring within 3-4 months. 2, 4

Recovery Rates Without Treatment

• 70% of patients with complete paralysis recover completely within 6 months 1, 2
• Up to 94% of patients with incomplete paralysis recover completely 1, 2
• 30% may experience permanent facial weakness with muscle contractures 1

Prognostic Factors

• Incomplete paralysis at presentation predicts faster and more complete recovery 1
• Complete paralysis with electrodiagnostic testing showing <10% function carries worse prognosis 1

Follow-Up and Reassessment

Mandatory reassessment or specialist referral is required at 3 months for incomplete facial recovery. 1, 2

Urgent Reassessment Triggers (At Any Time)

• New or worsening neurologic findings 1
• Development of ocular symptoms 1
• Progressive weakness beyond 3 weeks 1

Specialist Referral Indications

• Incomplete recovery at 3 months: refer to facial nerve specialist or facial plastic surgeon 1
• Persistent eye closure problems: refer to ophthalmology 1
• Reconstructive options include eyelid weights, brow lifts, static facial slings, nerve transfers 1

Special Populations

Children

Children have better prognosis than adults with higher spontaneous recovery rates (up to 90%), but evidence for corticosteroid benefit in children is inconclusive. 1, 4

• Consider oral corticosteroids (prednisolone 1 mg/kg/day, maximum 50-60 mg) for severe or complete paralysis with substantial caregiver participation in decision-making 1
• Most children recover completely without treatment 1

Pregnant Women

Treat pregnant women with oral corticosteroids within 72 hours using individualized assessment of benefits and risks. 1

• Eye protection measures are essential and safe in pregnancy 1
• Combination therapy with antivirals may be considered on individualized basis 1

Therapies NOT Recommended

Physical therapy has no proven benefit over spontaneous recovery in Bell's palsy. 6, 1

Acupuncture cannot be recommended due to poor-quality trials and indeterminate benefit-harm ratio. 6, 1

Surgical decompression is rarely indicated except in specialized centers for specific cases, and should not be routinely offered. 6, 1

Common Pitfalls to Avoid

• Delaying corticosteroid treatment beyond 72 hours eliminates proven benefit 1
• Prescribing antiviral monotherapy is ineffective and delays appropriate treatment 1
• Failing to implement eye protection can lead to permanent corneal damage 1
• Missing forehead involvement leads to misdiagnosis of central causes (stroke) 1
• Failing to refer at 3 months delays access to reconstructive options 1
• Using standard methylprednisolone dose pack provides only 105 mg prednisone equivalent vs required 540 mg over 14 days—this is significant underdosing 1