A patient develops a sudden unilateral facial droop; how should I evaluate for stroke versus Bell's palsy and what is the acute management?

Acute Unilateral Facial Droop: Stroke vs. Bell's Palsy Evaluation and Management

In a patient with sudden unilateral facial droop, immediately assess forehead function and perform a complete neurological examination—if the forehead is spared or any other neurological deficits are present (limb weakness, speech changes, altered mental status, gaze deviation), treat as stroke with urgent non-contrast CT and consider thrombolysis; if complete hemifacial weakness including forehead is present with isolated facial involvement and onset <72 hours, diagnose Bell's palsy and start oral corticosteroids immediately without imaging. 1

Immediate Triage: The Critical First Assessment

Forehead Function Test

• Test forehead wrinkling bilaterally—ask the patient to raise eyebrows and wrinkle the forehead. In Bell's palsy (peripheral lesion), the entire ipsilateral face including forehead is paralyzed because CN VII innervates all facial muscles after exiting the brainstem. 1 In stroke (central lesion), forehead muscles are typically spared due to bilateral cortical innervation, though this sparing is not absolute. 1

• Lower face predominance with forehead sparing = stroke until proven otherwise. 1 Immediately activate stroke protocol. 2

Systematic Neurological Red Flags

Perform rapid assessment for these stroke indicators:

• Limb weakness (unilateral arm or leg weakness) 2
• Speech disturbance (aphasia, dysarthria) 2
• Altered mental status or confusion 1
• Gaze deviation 1
• Dizziness, dysphagia, or diplopia 2, 1
• Any other cranial nerve involvement (CN V, VI, VIII, IX, X, XI, XII)—this excludes Bell's palsy and mandates stroke workup 2, 1

If ANY of these features are present, this is stroke until proven otherwise—proceed directly to stroke protocol. 1

Stroke Protocol Pathway

Immediate Actions (Within Minutes)

• Calculate NIHSS score to quantify deficits and facilitate team communication 2
• Obtain non-contrast CT head immediately to exclude hemorrhage 2, 1
• Check glucose, electrolytes, CBC, PT/INR, aPTT 2
• Obtain 12-lead ECG 2

Advanced Imaging for Stroke

• Perform CTA or MRA from aortic arch to vertex to identify large vessel occlusion if endovascular therapy is being considered 2, 1
• Consider diffusion-weighted MRI if CT is negative but clinical suspicion remains high, as MRI is more sensitive for acute cortical or small-vessel ischemia 1

Thrombolysis Consideration

• Administer IV alteplase (0.9 mg/kg, 10% bolus over 1 minute, remainder over 59 minutes) if patient presents within 4.5 hours of last known well and has no contraindications 2

Critical Caveat

• Pontine strokes can produce peripheral-pattern facial palsy (complete hemifacial weakness including forehead) but usually have additional brainstem signs. 1, 3 Maintain low threshold for imaging when subtle brainstem findings are present or when vascular risk factors are prominent. 1, 3

Bell's Palsy Diagnostic Pathway

Diagnostic Criteria (All Must Be Present)

• Rapid onset within 72 hours 2, 1, 4
• Complete unilateral facial weakness including forehead—inability to wrinkle forehead, close eye, or smile on affected side 2, 1, 5
• Isolated facial involvement with NO other neurological deficits 2, 1
• No identifiable cause after appropriate history and examination 2, 1

Essential History Elements

• Timing of onset—gradual progression beyond 72 hours suggests tumor, infection, or other pathology, not Bell's palsy 2, 1, 4
• Associated symptoms: ipsilateral ear or facial pain (common in Bell's palsy), taste disturbance from anterior tongue, hyperacusis, dry eye 2, 1
• Geographic/travel history—Lyme disease accounts for up to 25% of facial paralysis in endemic areas 2, 1, 4
• Vesicular rash in ear canal—indicates Ramsay Hunt syndrome (herpes zoster), which requires antiviral therapy and has worse prognosis 1, 4
• Recent trauma or surgery 2, 4
• Diabetes, pregnancy, hypertension, immunocompromised state—risk factors for Bell's palsy 1, 5

Physical Examination Priorities

• Document function of ALL cranial nerves—involvement of any other cranial nerve excludes Bell's palsy 2, 1, 6
• Examine ear canal for vesicular rash (Ramsay Hunt syndrome) 1, 4
• Assess facial swelling or erythema—atypical for Bell's palsy and suggests Lyme disease or other infectious cause 4
• Test taste on anterior two-thirds of tongue bilaterally 1
• Check for hyperacusis (increased sound sensitivity) 2, 1

When to Order Testing in Suspected Bell's Palsy

Do NOT order routine imaging or laboratory tests for typical Bell's palsy presentation. 2, 1

Order testing only if:

• Bilateral facial palsy—immediately test for Lyme disease, Guillain-Barré syndrome, or sarcoidosis 2, 1, 6, 4
• Recurrent paralysis on same side—obtain MRI to exclude tumor 1, 4
• Symptoms persist >2 months—obtain MRI orbit/face/neck with contrast plus brain MRI 1
• Gradual onset or atypical features—obtain MRI to exclude structural lesions 1, 4
• Geographic risk or facial swelling/erythema—obtain Lyme serology 1, 4
• Any other cranial nerve involvement—obtain urgent MRI 1, 6

Acute Management of Bell's Palsy

Immediate Pharmacologic Therapy

Start oral corticosteroids immediately (within 72 hours of onset for maximum benefit):

• Prednisolone 50 mg daily for 10 days OR
• Prednisone 60 mg daily for 5 days, then 5-day taper 1, 4

Evidence: 83% recovery at 3 months with prednisolone vs. 63.6% with placebo. 1

Antiviral Therapy

• Consider adding oral antivirals to corticosteroids—combination therapy shows 96.5% complete recovery vs. 89.7% with steroids alone, though benefit is modest 1
• Mandatory for Ramsay Hunt syndrome (herpes zoster with vesicular rash) 1, 4

Eye Protection (Mandatory)

Implement immediately to prevent permanent corneal damage:

• Lubricating ophthalmic drops during day 1, 6
• Ophthalmic ointment at night 1, 6
• Eye taping or patching if unable to close eye 1, 6

Therapies NOT Recommended

• Do NOT use physical therapy—no proven benefit over spontaneous recovery 1
• Do NOT use acupuncture—poor quality evidence with indeterminate benefit-harm ratio 1

Follow-Up Requirements

Mandatory reassessment or specialist referral if:

• New or worsening neurological findings 1
• Development of ocular symptoms 1
• Incomplete facial recovery at 3 months 1

Special Clinical Scenarios

Facial Palsy with Facial Swelling/Redness

• This is atypical for Bell's palsy—immediately consider Lyme disease (especially in endemic areas), Ramsay Hunt syndrome, or other infectious causes 4
• Obtain Lyme serology if geographically appropriate 4
• Examine for vesicular rash in ear canal 4
• If infection identified, start appropriate antimicrobials FIRST (e.g., IV ceftriaxone for Lyme disease), then add corticosteroids as adjunctive therapy 4

Bilateral Facial Palsy

• Never accept as idiopathic—immediately investigate for Guillain-Barré syndrome (ascending paralysis), Lyme disease, or sarcoidosis 2, 1, 6, 4

Older Adults with Vascular Risk Factors

• Maintain high suspicion for stroke—even isolated facial palsy can rarely be the sole manifestation of pontine infarct 1, 3
• Perform comprehensive neurological exam including all cranial nerves, limb strength, speech, and mental status 1
• Lower threshold for imaging when subtle brainstem signs present 1, 3

Common Pitfalls to Avoid

• Assuming all acute facial weakness is Bell's palsy—30% have identifiable causes requiring different management 2, 1, 4
• Missing stroke by not testing forehead function—forehead sparing indicates central lesion 1
• Failing to examine other cranial nerves—any additional cranial nerve involvement excludes Bell's palsy 2, 1, 6
• Ordering unnecessary imaging for typical Bell's palsy—delays treatment beyond critical 72-hour window without benefit 2, 1
• Missing Lyme disease in endemic areas—accounts for 25% of facial paralysis in these regions 2, 1, 4
• Giving corticosteroids alone when infection present—treat underlying infection with antimicrobials first 4
• Neglecting eye protection—can result in permanent corneal damage 1, 6
• Accepting bilateral facial palsy as Bell's palsy—this is never idiopathic 2, 1, 6, 4