Last Updated June 28, 2025
Definition
Bell’s palsy is an idiopathic, acute-onset peripheral facial nerve (CN VII) palsy, most commonly attributed to reactivation of HSV-1 at the geniculate ganglion, leading to inflammation and nerve compression. It characteristically affects both the upper and lower face, resulting in complete hemifacial weakness—including the inability to wrinkle the forehead.
CN VII also handles:
- Motor: facial expression
- Taste: anterior 2/3 tongue
- Parasympathetics: lacrimation, salivation
- Sensory: external ear
Pathophysiology
- Inflammation at the geniculate ganglion compresses the facial nerve.
- HSV-1 reactivation is most likely, but other triggers include:
- VZV (Ramsay Hunt)
- CMV, EBV
- Rarely: Influenza vaccine (Swiss intranasal), COVID-19, mumps
- Autoimmunity, ischemia, and microvascular neuropathy also theorized (esp. in diabetics).
Goldfrank’s reminds us that some environmental or drug triggers have been proposed, but causality is unclear.
Differential Diagnosis
Key Neuroanatomy
- Peripheral facial palsy: Affects forehead and lower face (due to lesion distal to nucleus).
- Central (UMN) lesion: Spares forehead (due to dual cortical innervation).
"The upper face has dual cortical innervation. Only a peripheral lesion knocks it all out.”
Bell vs. Stroke
Task | Bell’s Palsy | Central (Stroke) |
Raise eyebrows | Weak | Normal |
Smile | Weak | Weak |
Close eyes tightly | Incomplete | Normal |
Forehead involvement | Present | Spared |
Other neuro signs | Absent | Common (dysarthria, limb weakness, ataxia) |
Mislabeling a pontine stroke as Bell’s is one of the most common ED neuro misses. Don't shortcut the CN exam.
Red Flags and other diagnoses
The presence of any additional symptoms especially neurologic should prompt reconsideration of Bell’s palsy and a broader differential.
Feature | Think... |
Forehead spared | Stroke (esp. cortical) |
Vesicles in ear/mouth | Ramsay Hunt (Varicella Zoster Virus) |
Bilateral | GBS, Lyme, sarcoid, HIV |
Hearing loss or tinnitus | Cerebellopontine angle tumor |
Facial numbness | Trigeminal involvement = NOT Bell’s |
Recurrent episodes | Tumor, sarcoidosis, MS |
Progressive weakness | Tumor or MS |
Other neuro deficits (e.g. ataxia, vertigo) | Brainstem stroke or MS |
Faical Numbness | Trigeminimal Involvement |
Recent tick bite | Lyme disease |
Recurrent otitis media | Temporal bone or ear pathology |
Consider a bedside glucose test in patients with diabetes or risk factors—Bell’s is more common in this group, and hypoglycemia can mimic focal neuro deficits.
ED Management
History and Physical
- Ask about time course: rapid vs progressive
- Full cranial nerve and neuro exam—don’t skip strength, sensory or cerebellar testing
- Otoscopy: Ramsay Hunt, otitis, or cholesteatoma?
- Parotid exam: masses → facial nerve schwannoma or cancer
Testing (if indicated)
- None if classic Bell’s Palsy
- Consider further workup if no improvement by 3 weeks, recurrent/progressive or other red flags previously mentioned
- Outpatient electromyography (delayed 9–20 days) for prognostication, not acute ED use
Treatment within 72 hours
Medication | Dose | Duration | NNT |
Prednisone | 60–80 mg PO daily | 7 days | ~10 |
Prednisolone | 1 mg/kg/day PO | 7–10 days | ~10 |
Valacyclovir | 1 g PO TID | 7 days | ~19 (with steroids) |
Acyclovir | 400 mg PO 5x/day | 7 days | ~19 (with steroids) |
Corticosteroids are the cornerstone of Bell’s palsy treatment, with the strongest benefit seen when started within 72 hours of symptom onset. The NNT is 10 to prevent one case of incomplete recovery, based on high-quality meta-analyses. Early treatment improves facial nerve recovery and reduces long-term complications like synkinesis.
Recommended regimens include:
- Prednisolone 60 mg daily × 5 days, then taper
- Prednisolone 25 mg BID × 10 days
- Oral steroids are equally effective as IV, even in severe cases.
Start steroids early. Consider adding antivirals in moderate to severe cases—benefit is small but likely safe.
Adding antivirals (e.g., valacyclovir) offers a modest, borderline-significant benefit, with an NNT of 19. Antivirals alone do not improve outcomes and are not recommended as monotherapy. Combination therapy may be more beneficial in severe cases (House-Brackmann grade V–VI), but evidence is limited.
In patients with renal impairment or age >65, consider baseline creatinine, carefully renally dosing and advise hydration with valacyclovir .
Eye care is an underutilized but essential part of Bells Palsy management and post-visit care. Facial nerve dysfunction in Bell’s palsy leads to incomplete eyelid closure (lagophthalmos) and impaired blink reflex, which reduces tear distribution and increases exposure of the cornea. This sets the stage for corneal desiccation, exposure keratitis, abrasions, and ulcers—which can develop quickly and may lead to permanent vision loss if untreated. The risk of corneal injury is not related to how severe the facial paralysis looks, but rather how much eyelid closure is lost—even mild weakness can result in inadequate protection.
Recommended Intervention | Rationale |
Artificial tears (frequent use) | Maintain daytime corneal hydration and tear film stability |
Lubricating ointment at bedtime | Prevents overnight drying when blink reflex and lid closure are absent |
Eye patch or moisture shield at night | Provides mechanical protection and reduces evaporative loss |
Taping the eyelids closed | Alternative if patch not tolerated; should be taught properly to avoid corneal abrasions |
If the patient develops eye pain, irritation, redness, or blurred vision, refer urgently to ophthalmology—they may need advanced interventions.
Expectations for Recovery at 3-6 months
Most patients begin to show initial signs of recovery within 2–3 weeks, with continued improvement over 3 to 6 months.
Presentation | Recovery w/o Steroids | Recovery w/ Steroids |
All Bells Palsy | 71% | |
Incomplete paralysis | 94% | 97% |
Complete paralysis | 61% | 83% |
Poor Prognostic Indicators
These patients may recover more slowly or incompletely:
- Age > 60
- Complete facial paralysis at onset
- Loss of taste
- Pain beyond the ear
Counseling Points for the ED
- Set realistic expectations—even with treatment, recovery takes time.
- Emphasize eye protection
- Arrange outpatient follow-up (neurology or ENT)
Disposition
Scenario | Disposition | Action Steps |
Classic Bell’s palsy (sudden, unilateral, complete facial weakness with forehead involvement, no other neuro findings) | Discharge | - Start steroids (± antivirals)- Eye protection (tears + ointment + patch)
- Arrange outpatient follow-up (PCP, neurology, or ENT in 1 week) |
Incomplete eyelid closure (lagophthalmos) | Discharge | - Emphasize aggressive eye protection
- Ophthalmology follow-up if pain, redness, or vision changes |
No improvement after 3 weeks (on follow-up) | Outpatient neuro/ENT referral | - MRI with IAC if not already done
- Consider EMG |
Atypical features (bilateral, progressive, recurrent, or partial facial sparing) | Discharge with workup OR consider admission (case-dependent) | - MRI brain with IAC
- Labs
- Neuro/ENT follow-up |
Signs of corneal involvement (pain, redness, blurred vision) | Urgent ophthalmology referral or consult | - Immediate intervention to prevent ulceration
- Consider ED ophthalmology consult if available |
Systemic illness or unclear diagnosis (e.g., stroke not ruled out, meningitis, CPA tumor) | Admit | - Full neuro workup- MRI/MRA- Consult neurology |
Resources
- Bell’s Palsy – Core EM. Brennan Chang, https://coreem.net/core/bells-palsy/
- Bell’s Palsy in the ED – County EM. Warshaw D. EM Principles Blog. https://blog.clinicalmonster.com/2020/07/16/bells-palsy-in-the-ed/
- Baugh RF, Basura GJ, Ishii LE, et al. Clinical practice guideline: Bell’s palsy. Otolaryngol Head Neck Surg. 2013;149(3 Suppl):S1-S27. doi:10.1177/0194599813505967.
- Chou’s Electrocardiography in Clinical Practice. 6th ed. Philadelphia, PA: Elsevier; 2008.
- CorePendium – Bell Palsy. Khoujah D, et al. EM:RAP; 2024. https://www.emrap.org/corependium/chapter/recvMlu7VuFBIv6x4
- Decision Making in Emergency Medicine: Biases, Errors and Solutions. Raz M, Pouryahya P, eds. Academic Press; 2021.
- de Almeida JR, Al Khabori M, Guyatt GH, et al. Combined corticosteroid and antiviral treatment for Bell palsy: a systematic review and meta-analysis. JAMA. 2009;302(9):985-993. doi:10.1001/jama.2009.1243.
- Gagyor I, Madhok VB, Daly F, Sullivan F. Antiviral treatment for Bell’s palsy (idiopathic facial paralysis). Cochrane Database Syst Rev. 2019;9:CD001869. doi:10.1002/14651858.CD001869.pub9.
- Gronseth GS, Paduga R. Evidence-based guideline update: Steroids and antivirals for Bell palsy: Report of the Guideline Development Subcommittee of the American Academy of Neurology. Neurology. 2012;79(22):2209-2213. doi:10.1212/WNL.0b013e318275978c.
- Heckmann JG, Urban PP, Pitz S, Guntinas-Lichius O, Gágyor I. The diagnosis and treatment of idiopathic facial paresis (Bell’s palsy). Dtsch Arztebl Int. 2019;116(41):692-702. doi:10.3238/arztebl.2019.0692.
- Lockhart P, Daly F, Pitkethly M, et al. Antiviral treatment for Bell’s palsy (idiopathic facial paralysis). Cochrane Database Syst Rev. 2009;(4):CD001869.
- Madhok VB, Gagyor I, Daly F, et al. Corticosteroids for Bell’s palsy (idiopathic facial paralysis). Cochrane Database Syst Rev. 2016;7:CD001942. doi:10.1002/14651858.CD001942.pub5.
- Minor Emergencies. Buttaravoli P, Stair TO. 4th ed. Philadelphia, PA: Elsevier; 2017.
- Rosen’s Emergency Medicine: Concepts and Clinical Practice. Marx JA, Hockberger RS, Walls RM, eds. 8th ed. Philadelphia, PA: Elsevier; 2014.
- Sullivan F, Daly F, Gagyor I. Antiviral agents added to corticosteroids for early treatment of adults with acute idiopathic facial nerve paralysis (Bell palsy). JAMA. 2016;316(8):874-875. doi:10.1001/jama.2016.10160.
- Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. Tintinalli JE, Ma OJ, Yealy DM, et al, eds. 9th ed. New York, NY: McGraw-Hill; 2020.
- Yoo MC, Soh Y, Chon J, et al. Evaluation of factors associated with favorable outcomes in adults with Bell palsy. JAMA Otolaryngol Head Neck Surg. 2020;146(3):256-263. doi:10.1001/jamaoto.2019.4312.