What is Bell's palsy?

Bell's Palsy: Definition, Diagnosis, and Management

Bell's palsy is an acute unilateral facial nerve paresis or paralysis with onset in less than 72 hours without an identifiable cause, characterized by rapid onset of unilateral facial weakness or paralysis involving the forehead. 1

Clinical Presentation

• Bell's palsy presents as a rapid unilateral facial nerve weakness or complete paralysis, developing within 72 hours, affecting the ability to voluntarily move facial muscles on one side of the face 2
• Common symptoms include inability to close the eyelid, oral incompetence, dryness of the eye or mouth, taste disturbance, hyperacusis, and sagging of the eyelid or corner of the mouth 3
• The condition can cause significant temporary oral incompetence and inability to close the eyelid, potentially leading to eye injury 2

Etiology and Epidemiology

• Currently, no definitive cause for Bell's palsy has been identified, though viral etiology (particularly herpes simplex virus type 1) is suspected, with facial nerve inflammation and edema as the likely mechanism 3, 4
• Bell's palsy affects men, women, and children but is more common in those 15 to 45 years old 2
• Higher incidence is noted in patients with diabetes, upper respiratory ailments, compromised immune systems, and during pregnancy 3
• Incidence ranges from 11.5-53.3 per 100,000 individuals per year across different populations 4

Diagnosis

• Bell's palsy is diagnosed by exclusion after careful elimination of other causes of facial weakness 1
• Other conditions that may cause facial paralysis include stroke, brain tumors, tumors of the parotid gland or infratemporal fossa, cancer involving the facial nerve, and systemic and infectious diseases such as Herpes zoster, sarcoidosis, and Lyme disease 2, 3
• Red flags requiring further investigation include advanced age, bilateral facial weakness, and new or worsening neurologic findings 3
• Routine laboratory testing and diagnostic imaging are NOT recommended for initial Bell's palsy diagnosis 1
• MRI with and without contrast is the imaging test of choice when indicated, such as for atypical presentations or no sign of recovery after 3 months 1

Treatment

• Oral corticosteroids should be prescribed within 72 hours of symptom onset for Bell's palsy patients 16 years and older to significantly improve facial nerve recovery. 1
• The recommended regimen is prednisolone 50 mg daily for 10 days or prednisone 60 mg daily for 5 days followed by a 5-day taper 1
• Strong evidence supports corticosteroid use, with 83% recovery at 3 months with prednisolone vs 63.6% with placebo, and 94.4% recovery at 9 months with prednisolone vs 81.6% with placebo 1
• Antiviral therapy alone should not be prescribed for Bell's palsy, but may be offered in combination with oral steroids within 72 hours of symptom onset as an option 1
• Pregnant women with Bell's palsy should be treated with oral corticosteroids within 72 hours of symptom onset, with careful assessment of benefits and risks 1

Eye Protection

• Eye protection is strongly recommended for Bell's palsy patients with impaired eye closure to prevent corneal damage 1
• Implement the following eye protection measures:
  • Lubricating ophthalmic drops should be used frequently throughout the day 1
  • Ophthalmic ointments are recommended for more effective moisture retention, particularly at night 1
  • Moisture chambers using polyethylene covers can be particularly effective for nighttime protection 1
  • Eye patching or taping should be used with caution, particularly at night 1
  • Sunglasses are recommended for outdoor protection against foreign particles and irritants 1

Prognosis and Recovery

• Bell's palsy is typically self-limited, with most patients beginning to show recovery within 2-3 weeks 3
• Complete recovery typically occurs within 3-4 months for most patients 3
• Without treatment, facial function is completely restored in approximately 70% of patients with complete paralysis within 6 months, and up to 94% of patients with incomplete paralysis 3
• Patients with incomplete paralysis have higher recovery rates (up to 94%) compared to those with complete paralysis (approximately 70%) 1
• Approximately 30% of patients may experience permanent facial weakness with muscle contractures 1

Follow-up and Referral

• Patients should be reassessed or referred to a facial nerve specialist if they have:
  • New or worsening neurologic findings at any point 1
  • Ocular symptoms developing at any point 1
  • Incomplete facial recovery 3 months after initial symptom onset 1
• Patients with severe eye impairment should receive immediate ophthalmology referral for evaluation 1
• Patients with persistent lagophthalmos beyond 3 months should be referred to a facial nerve specialist or ophthalmologist 1

Special Considerations

• Children with Bell's palsy have a better prognosis than adults, with higher rates of spontaneous recovery 1
• The benefit of corticosteroid treatment in children is inconclusive 1
• Electrodiagnostic testing may be offered to patients with complete facial paralysis, but is NOT recommended for patients with incomplete facial paralysis 1
• Bell's phenomenon (upward and outward eye movement during attempted eyelid closure) helps protect the cornea in patients with lagophthalmos 1