What are the initial investigations and management for a patient presenting with left facial nerve palsy?

Left Facial Nerve Palsy: Initial Investigations and Management

For a patient presenting with left facial nerve palsy, immediately initiate oral corticosteroids (prednisolone 50 mg daily for 10 days or prednisone 60 mg daily for 5 days with 5-day taper) within 72 hours of symptom onset if Bell's palsy is suspected, while simultaneously implementing aggressive eye protection measures and conducting a focused history and physical examination to exclude secondary causes that would require imaging. 1, 2

Initial Clinical Assessment

History and Physical Examination:

• Document precise onset timing (<72 hours suggests Bell's palsy; gradual progression suggests tumor or infection) 1
• Assess forehead involvement (forehead weakness indicates peripheral lesion; forehead sparing suggests central/stroke) 1, 2
• Examine for bilateral involvement (bilateral palsy is NOT Bell's palsy and requires alternative diagnosis) 2
• Check for other cranial nerve deficits (involvement of CN V, VI, VIII, IX, X, XI, or XII excludes Bell's palsy) 1
• Inquire about recent trauma, ear pain, vesicular rash (Ramsay-Hunt), tick exposure (Lyme), or history of malignancy 1, 3
• Perform otoscopic examination to identify middle ear disease, cholesteatoma, or vesicles 1
• Grade severity using House-Brackmann scale (1=normal to 6=complete paralysis) 2

Diagnostic Testing Algorithm

Routine Testing NOT Recommended:

• Laboratory tests and imaging are NOT indicated for typical Bell's palsy presentation 1, 2
• Do not delay treatment waiting for test results in classic presentations 1

When to Order Investigations:

MRI with and without contrast is indicated for: 1, 2

• Atypical features (gradual onset, recurrent ipsilateral palsy, isolated branch paralysis)
• Other cranial nerve involvement
• No recovery after 2-4 months
• Progressive worsening after initial presentation
• Bilateral facial weakness
• New or worsening neurologic findings

High-resolution temporal bone CT (thin-section) is indicated for: 1

• Suspected temporal bone fracture or trauma
• Middle ear disease or cholesteatoma
• Presurgical planning
• Patients unable to undergo MRI
• Complementary to MRI when bony detail needed

CSF analysis should be considered for: 3

• Suspected Ramsay-Hunt syndrome (85% sensitivity)
• Suspected Lyme neuroborreliosis (100% sensitivity)
• Suspected viral/bacterial CNS infection (100% sensitivity)
• This is particularly important as these subgroups represent ~15% of facial palsy cases and require specific treatment 3

Electrodiagnostic testing (ENoG/EMG): 1, 2

• Offer to patients with complete facial paralysis
• NOT recommended for incomplete paralysis
• Optimal timing: 3-14 days post-onset (unreliable before 7 days or after 21 days)

• 10% nerve response amplitude predicts excellent prognosis

• <10% function indicates up to 50% risk of incomplete recovery

Immediate Management Protocol

Corticosteroid Therapy (MUST initiate within 72 hours): 1, 2

• Prednisolone 50 mg orally daily for 10 days OR
• Prednisone 60 mg orally daily for 5 days, then 5-day taper
• Evidence: 83% recovery at 3 months vs 63.6% placebo; 94.4% recovery at 9 months vs 81.6% placebo 2
• Do NOT prescribe beyond 72-hour window (no evidence of benefit) 2

Antiviral Therapy:

• Never prescribe as monotherapy (completely ineffective) 1, 2
• May offer valacyclovir 1000 mg TID for 7 days OR acyclovir 400 mg five times daily for 10 days in combination with steroids as an option (minimal added benefit) 2

Eye Protection (CRITICAL - implement immediately): 1, 2

• Lubricating drops every 1-2 hours while awake
• Ophthalmic ointment at bedtime
• Sunglasses outdoors
• Eye taping/patching at night with proper instruction (improper technique causes corneal abrasion)
• Consider moisture chambers for severe cases
• Urgent ophthalmology referral if: complete inability to close eye, signs of corneal exposure/damage, or severe lagophthalmos 2

Special Populations

Children: 2

• Better prognosis with higher spontaneous recovery rates than adults
• Steroid benefit unproven in pediatrics (no high-quality pediatric trials)
• Consider prednisolone 1 mg/kg/day (max 50-60 mg) for severe/complete paralysis with caregiver shared decision-making
• Inform families most children recover completely without treatment

Pregnancy: 2

• Treat with oral corticosteroids within 72 hours using individualized risk-benefit assessment
• Eye protection measures are essential and safe

Mandatory Reassessment and Referral Triggers

Refer to facial nerve specialist or ophthalmology for: 1, 2

• Incomplete facial recovery at 3 months
• New or worsening neurologic findings at any point
• Development of ocular symptoms at any point
• Atypical presentations requiring imaging

Critical Pitfalls to Avoid

• Delaying corticosteroids beyond 72 hours (treatment window closes) 2
• Prescribing antiviral monotherapy (completely ineffective) 1, 2
• Failing to test forehead function (misses central vs peripheral distinction) 2
• Inadequate eye protection (leads to permanent corneal damage) 2
• Ordering routine imaging for typical Bell's palsy (unnecessary cost, delays treatment) 1, 2
• Missing bilateral involvement (never Bell's palsy, requires alternative workup) 2
• Failing to refer at 3 months if incomplete recovery (delays reconstructive options) 2

Expected Outcomes

• 70% complete recovery in complete paralysis; 94% in incomplete paralysis 2, 4
• Most patients show recovery signs within 2-3 weeks 2
• Complete recovery typically occurs within 3-4 months 2
• 30% may experience permanent weakness with contractures 2