What is the diagnostic and treatment approach for a patient with Bell's palsy, including the use of the forehead test?

Bell's Palsy Forehead Test

What the Forehead Test Means

The forehead test is the critical distinguishing feature of Bell's palsy: patients with Bell's palsy CANNOT wrinkle their forehead or raise their eyebrow on the affected side, which differentiates it from central (stroke) causes of facial weakness where forehead function is preserved due to bilateral cortical innervation. 1

Diagnostic Approach

Clinical Diagnosis

• Bell's palsy is diagnosed clinically by acute unilateral facial nerve paresis or paralysis with onset in less than 72 hours, characterized by rapid onset of unilateral facial weakness involving the forehead, without an identifiable cause 1
• The diagnosis requires careful elimination of other causes through thorough history and physical examination 1
• Forehead involvement is the hallmark: patients cannot raise their eyebrow, wrinkle their forehead, or close their eye completely on the affected side 1, 2

Physical Examination Findings

• Systematically assess all facial movements: raising eyebrows, closing eyes tightly, smiling, and puffing out cheeks 1
• Use the House-Brackmann facial nerve grading system (grades 1-6) to assess severity 1, 3
• Look for associated symptoms: ipsilateral ear or facial pain, hyperacusis, taste disturbance on anterior two-thirds of tongue, and dry eye 1
• Evaluate eye closure carefully to assess risk of corneal exposure 1

Red Flags Requiring Further Investigation

• Bilateral facial weakness (rare in Bell's palsy, suggests alternative diagnosis) 1
• Isolated branch paralysis 3
• Other cranial nerve involvement 1, 3
• Recurrent paralysis on same side 3
• Gradual onset beyond 72 hours 1

Diagnostic Testing

• Routine laboratory testing and diagnostic imaging are NOT recommended for typical Bell's palsy diagnosis 1, 3
• MRI with and without contrast is the imaging test of choice ONLY for atypical presentations, no recovery after 3 months, or worsening symptoms 1, 3
• Electrodiagnostic testing may be offered to patients with complete facial paralysis (but NOT for incomplete paralysis) at 7-14 days after symptom onset 1, 4

Treatment Algorithm

First-Line Treatment (Within 72 Hours)

Prescribe oral corticosteroids within 72 hours of symptom onset for patients 16 years and older 1, 3:

• Prednisolone 50 mg daily for 10 days, OR
• Prednisone 60 mg daily for 5 days followed by a 5-day taper 1, 2
• Evidence shows 83% recovery at 3 months with prednisolone vs 63.6% with placebo, and 94.4% recovery at 9 months vs 81.6% with placebo 1

Combination Therapy Option

• May offer oral antiviral therapy (valacyclovir 1 g three times daily for 7 days OR acyclovir 400 mg five times daily for 10 days) in addition to oral steroids within 72 hours 1, 2
• Some evidence shows higher complete recovery rates with combination therapy (96.5%) compared to steroids alone (89.7%), though benefit is small 1
• Never prescribe antiviral monotherapy—it is ineffective 1, 2

Eye Protection (Critical for All Patients with Impaired Eye Closure)

Implement aggressive eye protection immediately to prevent corneal damage 1:

• Lubricating ophthalmic drops frequently throughout the day 1
• Ophthalmic ointments at night for moisture retention 1
• Eye patching or taping at night (with careful instruction on proper technique to avoid corneal abrasion) 1
• Sunglasses for outdoor protection 1
• Moisture chambers using polyethylene covers for nighttime 1

Urgent Ophthalmology Referral Indications

• Eye pain, vision changes, redness, discharge, foreign body sensation, or increasing irritation despite protection measures 1
• Severe impairment with complete inability to close eye 1

Follow-Up and Reassessment

Mandatory Reassessment or Specialist Referral

• Incomplete facial recovery at 3 months after symptom onset 1
• New or worsening neurologic findings at any point 1
• Ocular symptoms developing at any point 1

Expected Recovery Timeline

• Most patients begin showing signs of recovery within 2-3 weeks 1
• Complete recovery typically occurs within 3-4 months 1
• Approximately 70% of patients with complete paralysis recover completely within 6 months 1
• Patients with incomplete paralysis have higher recovery rates up to 94% 1
• 30% may experience permanent facial weakness with muscle contractures 1

Special Populations

Children

• Children have better prognosis with higher rates of spontaneous recovery (up to 90%) 1, 2
• Evidence for corticosteroid benefit in children is inconclusive 1
• Treatment decisions should involve substantial caregiver participation in shared decision-making 1

Pregnant Women

• Treat with oral corticosteroids within 72 hours on an individualized basis with careful assessment of benefits and risks 1
• Eye protection is essential 1

Common Pitfalls to Avoid

• Failing to test forehead function leads to misdiagnosis of stroke as Bell's palsy 1
• Delaying treatment beyond 72 hours reduces effectiveness 1
• Using antiviral therapy alone is ineffective 1, 2
• Improper eye taping technique can cause corneal abrasion 1
• Relying solely on drops without nighttime protection can lead to exposure keratitis 1
• Failing to refer at 3 months delays access to reconstructive options 1