What are the neurologic findings and management of Bell's (Bell's) palsy?

Neurologic Findings in Bell's Palsy

Bell's palsy presents with acute unilateral facial weakness or paralysis that characteristically involves the forehead, distinguishing it from central causes of facial weakness, with onset occurring over less than 72 hours. 1

Cardinal Neurologic Examination Findings

Facial Nerve Dysfunction (CN VII)

• Complete unilateral facial weakness affecting both upper and lower face, including inability to raise the eyebrow, close the eyelid, wrinkle the forehead, smile, or puff out the cheek on the affected side 1, 2
• Forehead involvement is the critical distinguishing feature from central (stroke) causes, where forehead function is typically preserved 1, 3
• Facial droop with sagging of the eyelid and corner of the mouth on the affected side 2
• Oral incompetence causing difficulty with eating, drinking, and speaking 1

Associated Neurologic Features

• Taste disturbance affecting the anterior two-thirds of the tongue (chorda tympani involvement) 1, 2
• Hyperacusis (increased sensitivity to sound) due to stapedius muscle dysfunction 1, 2
• Ipsilateral pain around the ear or face 1
• Dry eye and dry mouth from autonomic fiber involvement 1

Severity Grading

• The House-Brackmann facial nerve grading system (grades 1-6) should be used to assess severity, ranging from grade 1 (normal facial function) to grade 6 (total paralysis) 1
• Systematic assessment of all facial movements is required: raising eyebrows, closing eyes tightly, smiling, and puffing out cheeks 1

Critical Examination Approach

What Must Be Present

• Rapid onset over 24-72 hours 1
• Unilateral facial weakness involving forehead 1, 2
• No other cranial nerve abnormalities 3
• No other neurologic deficits 3

Red Flags Requiring Alternative Diagnosis

• Bilateral facial weakness (rare in Bell's palsy and suggests alternative diagnosis) 1
• Isolated branch paralysis rather than complete facial nerve distribution 1
• Other cranial nerve involvement 1
• Progressive worsening beyond 72 hours 2
• New or worsening neurologic findings at any point 1

Management Based on Findings

Immediate Treatment (Within 72 Hours)

• Prescribe oral corticosteroids immediately 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
• Evidence shows 83% recovery at 3 months with prednisolone versus 63.6% with placebo 1
• Do NOT prescribe antiviral monotherapy (ineffective) 1, 4
• May offer combination therapy (oral antiviral plus corticosteroid) within 72 hours, which shows 96.5% complete recovery versus 89.7% with steroids alone 1

Eye Protection (Critical for Lagophthalmos)

• Implement immediate eye protection for all patients with impaired eye closure to prevent corneal damage 1
• Frequent lubricating ophthalmic drops during the day 1
• Ophthalmic ointments at night for moisture retention 1
• Eye patching or taping at night with careful instruction on proper technique 1
• Sunglasses for outdoor protection 1
• Immediate ophthalmology referral for severe impairment 1

Diagnostic Testing

• Routine laboratory testing and imaging are NOT recommended for typical Bell's palsy presentation 1, 3
• Electrodiagnostic testing may be offered only for complete facial paralysis, NOT for incomplete paralysis 1
• MRI with and without contrast is indicated only for atypical presentations: second paralysis on same side, isolated branch paralysis, other cranial nerve involvement, or no recovery after 3 months 1

Follow-Up and Referral Triggers

• Mandatory reassessment or specialist referral at 3 months if incomplete facial recovery 1
• Immediate referral for new or worsening neurologic findings at any point 1
• Immediate referral for developing ocular symptoms 1
• Most patients begin recovery within 2-3 weeks, with complete recovery typically within 3-4 months 1, 2

Common Pitfalls to Avoid

• Failing to test forehead function leads to misdiagnosis of central versus peripheral facial weakness 1
• Delaying corticosteroid treatment beyond 72 hours significantly reduces effectiveness 1
• Using antiviral therapy alone is completely ineffective 1, 4
• Inadequate eye protection can cause permanent corneal damage 1
• Missing bilateral weakness or other cranial nerve signs suggests alternative diagnosis requiring imaging 1
• Failing to refer at 3 months delays access to reconstructive options for the 30% who develop permanent facial weakness 1