What is the initial approach to managing a patient with lower motor neuron (LMN) facial palsy, considering potential underlying causes and treatment options?

Management of Lower Motor Neuron Facial Palsy

Immediate Diagnostic Assessment

Clinicians must perform a thorough history and physical examination to exclude identifiable causes of facial paralysis before diagnosing Bell's palsy, as this is a diagnosis of exclusion requiring systematic evaluation of trauma, infection, tumor, stroke, and other cranial nerve involvement. 1, 2

Critical History Elements to Obtain:

• Onset timing: Symptoms developing over <72 hours suggest Bell's palsy; progressive weakness beyond 3 weeks indicates alternative diagnosis requiring immediate imaging 2, 3
• Trauma history: Temporal bone fracture or surgical injury 2
• Associated symptoms: Hyperacusis, taste disturbance on anterior two-thirds of tongue, dry eye/mouth, periauricular pain 2
• Red flags: Bilateral weakness (rare in Bell's palsy), isolated branch paralysis, other cranial nerve deficits, recurrent paralysis on same side 2, 3

Physical Examination Specifics:

• Forehead function testing is mandatory: Forehead involvement distinguishes LMN (Bell's palsy) from UMN (central) causes 2
• House-Brackmann grading: Grade 1 (normal) to 6 (complete paralysis) 2
• Eye closure assessment: Critical for determining corneal exposure risk 2
• Other cranial nerves: Any additional deficits mandate imaging even with LMN pattern 4, 3
• Cerebellar signs: Ataxia, nystagmus, or gaze palsy with LMN facial palsy indicates brainstem pathology requiring urgent MRI 4

Diagnostic Testing Algorithm

Routine laboratory testing and diagnostic imaging are NOT recommended for typical Bell's palsy presentations. 1, 2

When to Order MRI with and without contrast:

• Recurrent paralysis on same side 2
• Isolated branch paralysis 2
• Other cranial nerve involvement 2
• Progressive weakness beyond 3 weeks 2
• No recovery after 3 months 2
• Any additional neurological findings (even with LMN pattern) 4

Electrodiagnostic Testing:

• Do NOT perform in incomplete facial paralysis 1
• May offer to patients with complete paralysis, performed 3-14 days post-onset for reliable prognostic information 2

• 10% nerve response amplitude indicates excellent prognosis; <10% carries 50% risk of incomplete recovery 2

First-Line Treatment Protocol

Prescribe oral corticosteroids within 72 hours of symptom onset for patients ≥16 years old—this is the only proven effective treatment with 83% recovery at 3 months versus 63.6% with placebo. 1, 2

Steroid Regimen:

• Prednisolone 50 mg daily for 10 days OR 2
• Prednisone 60 mg daily for 5 days, then 5-day taper 2
• Weight-based dosing: 1 mg/kg/day (maximum 60 mg) for patients significantly above/below average weight 2

Antiviral Therapy:

• Never prescribe antivirals alone—this is ineffective and strongly contraindicated 1, 2
• May offer valacyclovir 1000 mg three times daily for 7 days OR acyclovir 400 mg five times daily for 10 days in addition to steroids within 72 hours 1, 2
• Benefit is minimal (96.5% vs 89.7% complete recovery), but risks are low 2

Eye Protection Protocol (Mandatory for All Patients)

Implement comprehensive eye protection immediately for all patients with impaired eye closure to prevent corneal damage—this is a strong recommendation with preponderance of benefit. 1, 2

Daytime Protection:

• Lubricating ophthalmic drops every 1-2 hours while awake 2
• Sunglasses outdoors for wind and particle protection 2

Nighttime Protection:

• Ophthalmic ointment at bedtime for sustained moisture 2
• Eye taping or patching with careful instruction on proper technique to avoid corneal abrasion 2
• Moisture chambers using polyethylene covers for severe cases 2

Urgent Ophthalmology Referral Indications:

• Complete inability to close eye 2
• Eye pain, vision changes, redness, discharge 2
• Signs of corneal exposure or damage 2

Pediatric Considerations

Children have better prognosis with higher spontaneous recovery rates than adults, but steroid benefit remains unproven in pediatrics—treatment decisions require substantial caregiver participation in shared decision-making. 2

• May consider prednisolone 1 mg/kg/day (maximum 50-60 mg) for 5 days with 5-day taper for severe/complete paralysis if caregivers prefer intervention 2
• No high-quality pediatric-specific trials exist 2
• Eye protection remains mandatory and safe 2

Mandatory Follow-Up and Referral Triggers

Reassess or refer to facial nerve specialist for: (1) incomplete recovery at 3 months, (2) new/worsening neurologic findings at any point, or (3) ocular symptoms at any point. 1, 2

Follow-Up Timeline:

• Initial visit within 72 hours for treatment initiation 2
• Early follow-up at 1-2 weeks to assess recovery trajectory and reinforce eye protection 2
• Mandatory reassessment at 3 months for incomplete recovery 1, 2

Specialist Referral for Long-Term Management:

• Facial nerve specialist or facial plastic surgeon for reconstructive options (static/dynamic procedures, nerve transfers) 2
• Ophthalmology for persistent lagophthalmos (tarsorrhaphy, eyelid weight implantation) 2
• Psychology/psychiatry for depression screening in persistent paralysis 2

Common Pitfalls to Avoid

• Anchoring bias: Using "Bell's palsy" for all facial palsies regardless of presentation leads to missed diagnoses 3
• Missing central causes: LMN pattern with ANY other neurological sign requires imaging—brainstem strokes can present with LMN facial palsy 4
• Delaying treatment: Steroids lose effectiveness beyond 72 hours 2
• Antiviral monotherapy: Never prescribe antivirals alone—this is ineffective 1, 2
• Inadequate eye protection: Failing to implement comprehensive measures leads to permanent corneal damage 2
• Missing 3-month follow-up: Delays access to reconstructive options and psychological support 2

Therapies NOT Recommended

• Surgical decompression: No recommendation can be made; rarely indicated except specialized cases 1, 2
• Acupuncture: No recommendation due to poor-quality trials 1, 2
• Physical therapy: No proven benefit over spontaneous recovery 1, 2