Bell's palsy is an acute, idiopathic, unilateral peripheral facial nerve (CN VII) paralysis characterized by sudden-onset facial weakness involving the forehead, with no identifiable cause. It is the most common cause of acute facial paralysis, accounting for 60–75% of all unilateral facial palsies, with an annual incidence of 20–37 per 100,000. [1-2] Prognosis is generally favorable — more than two-thirds of patients recover completely spontaneously, and up to 90% of children and pregnant women achieve full recovery. [1]
1. History
- Onset and timing: Acute onset (over 1–3 days), peaking within the first week. Confirm sudden onset — gradual progression (>72 hours) suggests non-idiopathic causes. [1][3-4]
- Laterality: Unilateral. Bilateral involvement is rare and should prompt alternative diagnoses (Guillain-Barré, Lyme, sarcoidosis). [1]
- Associated symptoms: Postauricular or periauricular pain (often precedes weakness), dysgeusia (altered taste on anterior 2/3 of tongue), hyperacusis, decreased lacrimation, drooling. [2][5]
- Viral prodrome: Recent URI, influenza-like illness, or cold sore. [1][6]
- Important negatives to elicit: No vesicular rash (Ramsay Hunt), no tick exposure or erythema migrans (Lyme), no limb weakness, no dysphagia/diplopia/dizziness, no hearing loss or tinnitus, no history of head/neck cancer or skin cancer. [1][3]
2. Alarm Features
- Forehead sparing → suggests upper motor neuron (central) lesion; evaluate for stroke. [1][7]
- Bilateral facial weakness → Guillain-Barré, Lyme, sarcoidosis, HIV. [1][8]
- Vesicular eruption on ear/palate → Ramsay Hunt syndrome (VZV); requires antiviral treatment. [8-9]
- Additional cranial nerve deficits (diplopia, dysphagia, hearing loss, vertigo) → brainstem lesion, cerebellopontine angle tumor, or skull base pathology. [1][3]
- Gradual onset (>72 hours) or progressive course → neoplasm, perineural spread of malignancy. [4][10]
- No improvement by 3 months → reconsider diagnosis; refer to facial nerve specialist. [3]
- Recurrent ipsilateral palsy → underlying tumor must be excluded. [1][3]
- Facial pain, numbness, or epiphora in the setting of known skin or salivary gland cancer → malignant facial paralysis. [4]
3. Medications
First-line treatment (initiate within 72 hours of onset)
- Prednisone 50–60 mg/day × 5 days, then taper over 5 days (NNT = 10 for complete recovery). Cumulative dose ≥450 mg associated with better outcomes. [1][11]
- Combination antiviral therapy (optional, may reduce synkinesis; NNT = 12):
- Valacyclovir 1 g TID × 7 days, OR
- Acyclovir 400 mg 5× daily × 10 days. [1][11]
- Do NOT prescribe antivirals alone — no benefit as monotherapy (Level A evidence against). [3][11]
Cautions
- Corticosteroids in children: No demonstrated benefit in a randomized trial. [1]
- Pregnant patients: Consensus supports corticosteroid use early in course despite limited evidence. [1]
- Monitor glucose in diabetic patients on corticosteroids.
4. Diet
- No specific dietary triggers or restrictions for Bell's palsy.
- Patients with severe oral incompetence may have difficulty with liquids — advise using a straw or eating on the unaffected side.
- Adequate hydration is important, particularly if on corticosteroids.
5. Review of Systems
- Neurologic: Limb weakness, numbness, vision changes, diplopia, dysphagia, dysarthria (rule out stroke/MS/GBS).
- ENT: Hearing loss, tinnitus, vertigo, ear pain, vesicular rash on ear or palate (Ramsay Hunt). [1][8]
- Ophthalmologic: Eye dryness, irritation, tearing, pain, blurred vision (exposure keratitis risk). [1][3]
- Dermatologic: Rash (erythema migrans for Lyme, vesicles for VZV). [9]
- Constitutional: Fever, weight loss, night sweats (infection, malignancy, sarcoidosis).
6. Collateral History and Family History
- Collateral: Confirm acute onset (witnessed by family), prior episodes, recent travel to Lyme-endemic areas, tick exposure, recent immunizations, sick contacts.
- Family history: Bell's palsy has a reported familial predisposition in some studies. Family history of autoimmune disease, diabetes, or hypertension may be relevant. [5]
- Social context: Occupation (outdoor work → tick exposure), immunosuppression (HIV risk factors).
7. Risk Factors
- Diabetes mellitus [1][7]
- Hypertension [1][7]
- Pregnancy (especially third trimester and first postpartum week) [1][6]
- Immunosuppression (HIV, transplant recipients) [1]
- Upper respiratory infections / influenza [1][6]
- Age: Peak incidence 15–45 years, with a second peak in those >70 [1-2]
- Prior Bell's palsy (recurrence rate ~12%) [5]
8. Differential Diagnosis
Approximately 25–30% of acute facial palsies have an identifiable cause and are NOT Bell's palsy. [3][9]
- Stroke (central facial palsy): Forehead sparing, other neurologic deficits (hemiparesis, speech changes). Cannot-miss diagnosis. [1][7]
- Ramsay Hunt syndrome (VZV): Vesicular eruption on ear/palate, severe otalgia, hearing loss. Worse prognosis than Bell's palsy. Requires antivirals. [8-9]
- Lyme disease: Tick exposure, erythema migrans, bilateral palsy possible. Check Lyme serology in endemic areas. [8-9]
- Otitis media / mastoiditis / cholesteatoma: Ear pain, otorrhea, conductive hearing loss. [9][12]
- Parotid tumor / cerebellopontine angle tumor: Gradual onset, progressive course, palpable mass. [3-4]
- Guillain-Barré syndrome (Miller Fisher variant): Bilateral facial weakness, areflexia, ascending weakness. [8]
- Sarcoidosis (Heerfordt syndrome): Bilateral palsy, parotid swelling, uveitis, fever. [8]
- Multiple sclerosis: Young patient, other neurologic symptoms, relapsing-remitting course. [1]
- Perineural spread of cutaneous malignancy: History of skin cancer on head/face, facial numbness, pain. [4]
9. Past Medical History
- Prior episodes of facial palsy (recurrence suggests tumor or systemic cause) [1][3]
- Diabetes, hypertension (risk factors and affect prognosis) [1][7]
- History of head/neck cancer, skin cancer, parotid tumors [3-4]
- HIV/immunosuppression [7]
- Recent facial/head trauma
- Autoimmune conditions (sarcoidosis, Sjögren's, MS) [7]
- Pregnancy status [1]
10. Physical Exam
Key exam findings
- Unilateral facial weakness involving the forehead — ask patient to raise eyebrows, close eyes tightly, frown, show teeth, puff cheeks, pucker lips. [1]
- Mouth droop, flattened nasolabial fold, inability to close eye, smoothed brow on affected side. [1]
- If forehead is spared → central lesion (stroke) until proven otherwise. [1]
Focused exam maneuvers
- Complete cranial nerve exam — document all 12 cranial nerves. Any additional CN deficit argues against Bell's palsy. [3]
- Otoscopy: Vesicles on tympanic membrane or ear canal (Ramsay Hunt); middle ear effusion/cholesteatoma. [3]
- Parotid palpation: Mass suggests tumor.
- Skin exam: Erythema migrans (Lyme), vesicles (VZV), skin cancers on head/face. [4]
- Eye exam: Assess degree of lagophthalmos (incomplete eye closure), Bell's phenomenon (upward eye rolling on attempted closure — protective), corneal sensation. [3]
Severity grading: Use the House-Brackmann scale (Grade I = normal → Grade VI = total paralysis): [1]
- Grade I: Normal
- Grade II: Slight weakness, complete eye closure with minimal effort
- Grade III: Obvious asymmetry, complete eye closure with effort
- Grade IV: Disfiguring asymmetry, incomplete eye closure
- Grade V: Barely perceptible movement
- Grade VI: No movement
11. Lab Studies
- Routine labs are NOT required for typical Bell's palsy (AAO-HNS strong recommendation against). [1][3]
- When to obtain labs:
- Lyme serology (IgM/IgG ELISA with Western blot confirmation) — in endemic areas or with suggestive history [1][9]
- CBC, ESR/CRP — if infection or inflammatory cause suspected
- Glucose/HbA1c — screen for diabetes (risk factor and prognostic factor) [7]
- HIV testing — if risk factors present [7]
- ACE level — if sarcoidosis suspected
- RPR/VDRL — if syphilis is a concern
12. Imaging
- Routine imaging is NOT recommended for new-onset Bell's palsy (AAO-HNS strong recommendation against). Despite this, imaging is performed in ~50% of ED visits. [3][13]
- When to image:
- Atypical features (gradual onset, additional CN deficits, forehead sparing)
- Suspicion for stroke → CT head (emergent) or MRI brain
- Recurrent ipsilateral palsy → MRI with contrast of brain, internal auditory canals, and parotid [1]
- No improvement at 3 months → MRI with gadolinium [1][3]
- History of head/neck malignancy → MRI to evaluate for perineural tumor spread [4][12]
- MRI with contrast is the gold standard for evaluating structural causes; it has 88% sensitivity for neoplasms and 83% for otogenous processes. [9]
- ACR Appropriateness Criteria support MRI for atypical presentations. [12]
13. Special Tests
- House-Brackmann Grading Scale: Standard severity classification (Grades I–VI). [1]
- Sunnybrook Facial Grading System: More granular assessment of facial movement, synkinesis, and symmetry at rest. [1][14]
- Electroneurography (ENoG):
- Not indicated for incomplete paralysis (AAO-HNS recommendation against). [3]
- May be offered for complete paralysis (HB Grade VI) to provide prognostic information. [3]
- Optimal timing: 7–14 days after onset (Wallerian degeneration must be complete for meaningful results). [3][15]
- >90% degeneration on ENoG within 14 days predicts poor outcome. [3][15]
- If response amplitude on affected side exceeds 10% of contralateral side, most patients recover normal or near-normal function. [3]
- Needle EMG: Can be performed ~2 weeks post-onset; fibrillation potentials and positive sharp waves indicate axonal degeneration and predict worse outcomes. [15]
14. ECG
- ECG is not routinely indicated for Bell's palsy.
- Obtain ECG if stroke is being considered in the differential (particularly if forehead is spared or other neurologic deficits are present) — to evaluate for atrial fibrillation as a cardioembolic source.
15. Assessment
- Bell's palsy is a clinical diagnosis of exclusion — acute-onset, unilateral, peripheral (lower motor neuron) facial weakness involving the forehead, without identifiable cause. [1][3][10]
- Severity stratification using House-Brackmann scale guides prognosis and treatment decisions: [1]
- Incomplete paralysis (HB II–IV): Very high likelihood of complete recovery [3]
- Complete paralysis (HB V–VI): Higher risk of incomplete recovery (~50%); consider ENoG for prognostication [3][16]
- Prognosis: 85% begin improving within 3 weeks; 70%+ achieve complete spontaneous recovery; up to 94% with steroid treatment. [1-2][7]
- Poor prognostic factors: Older age, hypertension, diabetes, complete paralysis, impaired taste, pain beyond the ear. [7]
- Complications: Synkinesis (aberrant nerve regeneration), contracture, crocodile tears (gustatory lacrimation), exposure keratopathy. [2][6][17]
16. Treatment Plan
The following figure from the AAFP summarizes the treatment approach:
Initial management (within 72 hours of onset)
- Oral corticosteroids (Level A recommendation):
- Consider adding antiviral (Level C; may reduce synkinesis):
Eye protection (mandatory for incomplete eye closure)
- Artificial tears (preservative-free) during the day [1][3]
- Lubricating ointment (e.g., lacri-lube) at night [3][18]
- Eyelid taping or moisture chamber at night [3]
- Educate on signs of keratitis (pain, redness, vision changes) → urgent ophthalmology referral [1][3]
Adjunctive
- Physical therapy may benefit patients with severe paralysis, though evidence is limited. [1][19]
- No recommendation for or against acupuncture. [3]
- Surgical decompression: Insufficient evidence; not routinely recommended. [1][3]
17. Disposition
- Discharge home — Bell's palsy is managed as an outpatient condition. The vast majority of ED visits result in discharge. [13][20]
- Admission is rarely needed and only if:
- Stroke cannot be excluded and further emergent workup is required
- Severe comorbidities requiring inpatient management
- Inability to tolerate oral medications
Specialist consultation triggers
- New or worsening neurologic findings at any point → Neurology [3]
- Ocular symptoms (pain, irritation, vision changes) → Ophthalmology [3]
- Incomplete recovery at 3 months → Facial nerve specialist / Otolaryngology [3]
- Suspected Ramsay Hunt, Lyme, or neoplastic cause → appropriate specialist [3]
- Recurrent ipsilateral palsy → imaging and specialist referral [1][3]
18. Follow Up / Return Precautions
Follow-up timing
- Primary care follow-up within 1–2 weeks to reassess facial function and eye status.
- If no improvement by 3 weeks, closer monitoring is warranted (85% should begin improving by this point). [2]
- If incomplete recovery at 3 months, refer to facial nerve specialist and obtain MRI. [3]
Return precautions — advise patients to return immediately for:
- Worsening facial weakness or new neurologic symptoms (limb weakness, speech changes, vision changes)
- Eye pain, redness, vision changes, or foreign body sensation (exposure keratitis)
- Vesicular rash on ear or face
- Fever, headache, neck stiffness
Patient counseling
- Reassure that prognosis is good — most patients recover fully within weeks to months. [1-2]
- Emphasize importance of eye protection — this is the most critical self-care measure.
- Complete the full steroid course as prescribed.
- Expected recovery: Most improvement within 3–6 months; residual synkinesis may develop in some patients. [2][6]
References
1. Bell Palsy: Rapid Evidence Review. — Dalrymple SN, Row JH, Gazewood J. American Family Physician. 2023.
2. Corticosteroids and Antiviral Treatment for Bell's Palsy (Idiopathic Facial Paralysis). — Kurotschka PK, Daly F, Gagyor I, et al. The Cochrane Database of Systematic Reviews. 2026.
3. Clinical Practice Guideline: Bell's Palsy. — Baugh RF, Basura GJ, Ishii LE, et al. Otolaryngology--Head and Neck Surgery : Official Journal of American Academy of Otolaryngology-Head and Neck Surgery. 2013.
4. A Multi-Institutional Review of Characteristics of Idiopathic Versus Non-Idiopathic Facial Paralysis. — Mandava S, Gossett K, Monaghan NP, et al. The Laryngoscope. 2025.
5. Bell Palsy: Facts and Current Research Perspectives. — Rajangam J, Lakshmanan AP, Rao KU, et al. CNS & Neurological Disorders Drug Targets. 2022.
6. Antiviral Treatment for Bell's Palsy (Idiopathic Facial Paralysis). — Gagyor I, Madhok VB, Daly F, Sullivan F. The Cochrane Database of Systematic Reviews. 2019.
7. Bell's Palsy. — Gilden DH. The New England Journal of Medicine. 2004.
8. Approach to Facial Weakness. — Wang Y, Cruz CD, Stern BJ. Seminars in Neurology. 2021.
9. Differential Diagnosis of Peripheral Facial Nerve Palsy: A Retrospective Clinical, MRI and CSF-based Study. — Zimmermann J, Jesse S, Kassubek J, Pinkhardt E, Ludolph AC. Journal of Neurology. 2019.
10. Facial Nerve Palsy: Clinical Practice and Cognitive Errors. — George E, Richie MB, Glastonbury CM. The American Journal of Medicine. 2020.
11. Evidence-Based Guideline Update: Steroids and Antivirals for Bell Palsy: Report of the Guideline Development Subcommittee of the American Academy of Neurology. — Gronseth GS, Paduga R. Neurology. 2012.
12. ACR Appropriateness Criteria® Cranial Neuropathy: 2022 Update. — Expert Panel on Neurological Imaging, Rath TJ, Policeni B, et al. Journal of the American College of Radiology : JACR. 2022.
13. National Characterization of Bell's Palsy Management in the Emergency Department 2006 to 2022. — Renne A, Leu GR, Nellis JC, Boahene KDO. Otolaryngology--Head and Neck Surgery : Official Journal of American Academy of Otolaryngology-Head and Neck Surgery. 2026.
14. Clinical and Electrophysiological Prognostic Factors in Predicting Poor Outcomes in Patients With Idiopathic Facial Nerve Paralysis. — Zheng L. Journal of Clinical Neuroscience : Official Journal of the Neurosurgical Society of Australasia. 2024.
15. Evaluation of Factors Associated With Favorable Outcomes in Adults With Bell Palsy. — Yoo MC, Soh Y, Chon J, et al. JAMA Otolaryngology-- Head & Neck Surgery. 2020.
16. Determining the Prognosis of Bell's Palsy Based on Severity at Presentation and Electroneuronography. — Escalante DA, Malka RE, Wilson AG, et al. Otolaryngology--Head and Neck Surgery : Official Journal of American Academy of Otolaryngology-Head and Neck Surgery. 2022.
17. Clinical Features, Evaluation, and Management of Ophthalmic Complications of Facial Paralysis: A Review. — Moncaliano MC, Ding P, Goshe JM, et al. Journal of Plastic, Reconstructive & Aesthetic Surgery : JPRAS. 2023.
18. The Diagnosis and Treatment of Idiopathic Facial Paresis (Bell's Palsy). — Heckmann JG, Urban PP, Pitz S, Guntinas-Lichius O, Gágyor I. Deutsches Arzteblatt International. 2019.
19. Physical Therapy for Bell's Palsy (Idiopathic Facial Paralysis). — Teixeira LJ, Valbuza JS, Prado GF. The Cochrane Database of Systematic Reviews. 2011.
20. Evaluation and Treatment of Acute Facial Palsy: Opportunities for Optimization at a Single Institution. — von Sneidern M, Saeedi A, Abend AM, et al. Facial Plastic Surgery & Aesthetic Medicine. 2025.