What is the recommended approach for a patient presenting with symptoms of facial nerve dysfunction, regardless of age or medical history?

Facial Nerve Examination in Suspected Facial Nerve Dysfunction

Clinicians must perform a systematic history and physical examination to exclude identifiable causes of facial paresis or paralysis before diagnosing Bell's palsy, as approximately 30% of cases have identifiable etiologies requiring different management. 1, 2

Critical History Elements

Onset timing is the single most important historical feature. Bell's palsy develops rapidly over less than 72 hours, while neoplastic or infectious causes progress gradually over days to weeks, and stroke presents with sudden onset often accompanied by other neurologic deficits. 2, 3

Key Questions to Ask:

• Temporal progression: Onset within 72 hours suggests Bell's palsy; gradual progression beyond 3 weeks is a red flag requiring immediate reassessment for tumor or other pathology 2, 3
• Geographic and exposure history: Travel to or residence in Lyme-endemic areas (accounts for up to 25% of facial paralysis in these regions) 2
• Associated symptoms: Vesicular rash in ear canal (Ramsay Hunt syndrome), facial swelling/redness (atypical for Bell's palsy, suggests infection), otalgia, hyperacusis, taste disturbance 2, 3
• Trauma history: Temporal bone fracture or recent surgery 3
• Medical comorbidities: Diabetes, hypertension, pregnancy, obesity, recent upper respiratory infection 4
• Previous episodes: Recurrent paralysis on the same side warrants imaging for tumor 3

Systematic Physical Examination

The examination must assess all branches of the facial nerve systematically, with forehead function being critical to distinguish peripheral (lower motor neuron) from central (upper motor neuron) lesions. 2, 3

Motor Function Assessment:

• Forehead/frontalis: Ask patient to raise eyebrows and wrinkle forehead—involvement indicates peripheral lesion; sparing suggests central cause 2, 3
• Eye closure/orbicularis oculi: Assess ability to close eyes tightly—incomplete closure (lagophthalmos) requires immediate eye protection measures 1, 3
• Midface/smile: Evaluate smile symmetry and nasolabial fold depth 3
• Lower face: Test ability to puff out cheeks, show teeth, purse lips 3

Grading Severity:

Use the House-Brackmann scale (Grade 1 = normal to Grade 6 = total paralysis) to document baseline severity and track recovery. 3, 5

Additional Examination Components:

• Ear examination: Look for vesicular rash (Ramsay Hunt syndrome), signs of otitis media or mastoiditis 2, 3
• Skin examination: Assess for facial swelling, erythema, or erythema migrans rash (Lyme disease) 2
• Taste testing: Test anterior two-thirds of tongue if equipment available 3
• Other cranial nerves: Involvement of additional cranial nerves suggests alternative diagnosis (not Bell's palsy) 1, 3
• Complete neurologic examination: Assess for stroke, brainstem lesions, or other central pathology 2

Red Flags Requiring Immediate Further Investigation

The following features are atypical for Bell's palsy and mandate additional workup:

• Bilateral facial weakness: Never accept as idiopathic—investigate for Lyme disease, sarcoidosis, or Guillain-Barré syndrome 2, 3
• Isolated branch paralysis: Suggests focal pathology rather than Bell's palsy 3
• Progressive weakness beyond 3 weeks: Requires immediate imaging for tumor 3
• Facial swelling and redness: Atypical for Bell's palsy; investigate for Lyme disease or other infection 2
• Other cranial nerve involvement: Indicates broader pathology 1, 3
• Recurrent paralysis on same side: Warrants imaging for tumor 3

Diagnostic Testing Strategy

Routine laboratory testing and diagnostic imaging are NOT recommended for typical Bell's palsy presentations. 1, 3, 6

When to Order Tests:

• Lyme serology: In endemic areas, with travel history, or if facial swelling/erythema present 2
• MRI with and without contrast: For atypical features (bilateral weakness, isolated branch paralysis, other cranial nerve involvement, no recovery after 3 months, progressive weakness, recurrent paralysis) 3
• Electrodiagnostic testing: May be offered to patients with complete facial paralysis (not recommended for incomplete paralysis); most reliable when performed 3-14 days post-onset 1, 3, 7

Common Pitfalls to Avoid

• Failing to test forehead function: This is the critical distinguishing feature between peripheral and central lesions 2, 3
• Assuming all acute facial weakness is Bell's palsy: 30% have identifiable causes requiring different management 2
• Missing subtle weakness: Inadequate assessment can lead to delayed diagnosis 3
• Inadequate eye assessment: Failure to recognize lagophthalmos risks permanent corneal damage 3
• Accepting bilateral weakness as Bell's palsy: This is never idiopathic and requires investigation 2, 3

Immediate Management Considerations

Once Bell's palsy is diagnosed by exclusion, oral corticosteroids must be prescribed within 72 hours of symptom onset for patients 16 years and older (prednisolone 50 mg daily for 10 days OR prednisone 60 mg daily for 5 days followed by 5-day taper). 1, 3, 6

Eye protection is mandatory for all patients with impaired eye closure: lubricating drops every 1-2 hours while awake, ophthalmic ointment at bedtime, eye taping/patching with proper instruction, and sunglasses outdoors. 1, 3