Bell Palsy – Causes, Symptoms, Diagnosis, Treatment and Ongoing care



A peripheral lower motor neuron facial palsy, usually unilateral, which arises secondary to inflammation and subsequent swelling and compression of the 7th (facial) cranial nerve and the associated vasa nervorum.


  • Affects 0.02% of the population annually (1)[B]:
    • Most patients recover, but as many as 30% are left with facial disfigurement and pain (2)[B]
  • Accounts for 60–75% of all cases of unilateral facial paralysis (3)[A]
  • Predominant age:
    • Median age of onset is 40 years, but affects all ages (4)[A]
  • Predominant sex: Male = Female (4)[A]


  • US: 20–30 cases per 100,000 people per year (4)[A]
  • Lowest in children ≤10 years of age; highest in people ≥70 (4)[A]
  • Higher among pregnant women (3)[A]
  • Occurs with equal frequency on the left and right sides of the face (4)[A]


Affects 40,000 Americans every year (5)[A]

Risk Factors

  • Pregnancy
  • Diabetes mellitus
  • Age >30
  • Exposure to cold temperatures
  • Upper respiratory infection (e.g., coryza, influenza)


A genetic predisposition may be associated with Bell palsy, but it is unclear which factors are inherited.


  • Results from damage to the 7th (facial) cranial nerve
  • Inflammation of the 7th nerve causes swelling and subsequent compression of both the nerve and the associated vasa nervorum
  • May arise secondary to reactivation of latent herpes virus (HSV type 1 and herpes zoster virus) in cranial nerve ganglia (3)[A]
  • May arise secondary to ischemia from arteriosclerosis associated with diabetes mellitus (4)[A]

Commonly Associated Conditions

  • Herpes simplex virus
  • Lyme disease
  • Diabetes mellitus
  • Hypertension
  • Herpes zoster virus
  • Ramsay-Hunt syndrome
  • Sjögren syndrome
  • Sarcoidosis
  • Eclampsia
  • Amyloidosis

Herpes zoster, Bell's palsy, Lyme disease, Immunoglobulin G, Immunoglobulin M, Ramsay-Hunt, Chickenpox, Varicella zoster virus, herpes simplex virus,



  • Time course of the illness (rapid onset)
  • Any predisposing factors (e.g., recent viral infection, trauma, new medications, hypertension, diabetes mellitus)
  • Presence of hyperacusis or history of recurrent Bell palsy (both associated with poor prognosis)
  • Any associated rash (suggestive of herpes zoster, Lyme disease, or sarcoid)
  • Weakness on affected side of face, often sudden in onset
  • Pain in or behind the ear in 50% of cases (may precede the palsy in 25% of cases) (4)[A]
  • Subjective numbness on the ipsilateral side of the face
  • Alteration of taste on the ipsilateral anterior 2/3 of the tongue (chorda tympani branch of the facial nerve)
  • Hyperacusis (nerve to the stapedius muscle)
  • Decreased tear production

Physical Exam

  • Neurologic:
    • Determine if the weakness is due to a problem in either the central or peripheral nervous systems
    • Flaccid paralysis of muscles on the affected side, including the forehead:
      • Impaired ability to raise the ipsilateral eyebrow
      • Impaired closure of the ipsilateral eye
      • Bell phenomenon: Upward diversion of the eye with attempted closure of the lid
      • Impaired ability to smile, grin, or purse the lips
    • Patients may complain of numbness, but on sensory testing, no deficit is present
    • Examine for involvement of other cranial nerves
  • HEENT:
    • Carefully examine head, neck, and oropharynx to exclude masses
    • Perform pneumatic otoscopic exam
  • Skin:
    • Examine for erythema migrans (Lyme disease) and vesicular rash (herpes zoster virus)

Diagnostic Tests & Interpretation


Initial lab tests

  • Lyme titer and IgM, IgG, and IgA for B. burgdorferi
  • Salivary PCR for HSV1 or herpes zoster virus (these tests are largely reserved for research purposes) (3)[A]
  • IgM, IgG, and IgA titers for varicella zoster virus, cytomegalovirus, rubella, hepatitis A, hepatitis B, and hepatitis C
  • ESR
  • Blood glucose level
  • CBC
  • RPR test
  • HIV test

Follow-Up & Special Considerations

CSF analysis:

  • Not routinely indicated
  • CSF protein is elevated in 1/3 of cases
  • CSF cells show mild elevation in 10% of cases with a mononuclear cell predominance.


Initial approach

  • Facial radiographs:
    • Rule out fractures.
  • CT:
    • Rule out fractures.
    • Rule out stroke.
  • Brain MRI:
    • Not routinely indicated
    • Rule out central pontine, temporal bone, and parotid neoplasms (4)[A].

Diagnostic Procedures/Surgery

  • EMG:
    • Nerve conduction on affected and nonaffected sides can be compared to determine extent of nerve injury.
  • Electroneurography:
    • Evoked potentials of affected and nonaffected sides can be compared.

Pathological Findings

Invasive diagnostic procedures are not indicated because biopsy could further damage the 7th cranial nerve.

Differential Diagnosis

  • Infectious:
    • Lyme disease
    • Herpes zoster (Ramsay-Hunt syndrome)
    • Acute or chronic otitis media
    • Malignant otitis externa
    • Osteomyelitis of the skull base
    • Infectious mononucleosis
    • Leprosy
  • Trauma:
    • Temporal bone fracture
    • Mandibular bone fracture
  • Neoplastic (onset of palsy is usually slow and progressive, and accompanied by additional cranial nerve deficits and/or headache) (3)[A]:
    • Tumors of the parotid gland
    • Cholesteatoma
    • Skull-base tumor
    • Carcinomatous meningitis
    • Leukemic meningitis
  • Cerebrovascular:
    • Brainstem stroke involving anteroinferior cerebellar artery
    • Aneurysm involving carotid, vertebral, or basilar arteries
  • Other:
    • Multiple sclerosis
    • Myasthenia gravis (should be considered in cases of recurrent or bilateral facial palsy) (4)[A]
    • Guillain-Barré syndrome (may also present with bilateral facial palsy) (4)[A]
    • Sjögren syndrome
    • Sarcoidosis
    • Amyloidosis
    • Melkersson-Rosenthal syndrome
    • Polyneuritis



  • Debate had existed over whether pharmacologic intervention with anti-inflammatory and/or antiviral agents is any more beneficial than watchful waiting for the treatment and prevention of long-term effects.
  • Recent randomized control trials demonstrate definitively that corticosteroids decrease inflammation and limit nerve damage, thereby reducing the number of patients with residual facial weakness (6)[A].
  • Evidence now shows that antivirals targeting herpes simplex are no more effective than placebo at producing full recovery (7)[A].
    • Antivirals are also less likely to produce full recovery than corticosteroids (1)[B].
    • A combination of valacyclovir and steroids provides minimal added benefit over steroid use alone (1)[B].
  • Corticosteroids:
    • Prednisone (8)[B]: Total from 410 mg over 10 days to 760 mg PO over 16 days, tapering dose (adults only)
      • Treatment should begin immediately after onset, and should not be instituted if symptoms have been present for >7 days.
      • May reduce edema around the 7th cranial nerve.
    • Prednisolone (9)[B]: Total of 500 mg over 10 days, 25 mg PO b.i.d.:
      • Prednisolone alone may be an effective treatment.
      • Should be instituted within 72 hours of symptom onset
  • Antivirals in combination with corticosteroids:
    • Valacyclovir (1)[B]: 1000 mg × 5 days plus prednisone 60 mg/day × 5 days then 30 mg/day × 3 days then 10 mg/day × 2 days
  • Contraindications:
    • Documented hypersensitivity
    • Preexisting infections, including TB and systemic mycosis
  • Precautions: Use with discretion in pregnancy, peptic ulcer disease, and diabetes
  • Significant possible interactions: Measles-mumps rubella, oral polio virus vaccine, and other live vaccines

Pregnancy Considerations

Steroids should be used cautiously in pregnancy; consult with an obstetrician.

Additional Treatment

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General Measures

  • Artificial tears should be used to lubricate the cornea.
  • The ipsilateral eye should be patched and taped shut at night to avoid drying and infection.

Issues for Referral

Patients may need to be referred to an ENT specialist or a neurologist.

Additional Therapies

  • Physical therapy: No evidence of significant benefit or harm, but there is a possibility that facial exercises may reduce time to recover and/or sequelae (10)[A].
  • Electrostimulation has limited evidence of effect; more studies needed (11)[B].

Surgery/Other Procedures

  • Surgical treatment of Bell palsy remains controversial and is reserved for intractable cases (3)[A].
  • The 7th cranial nerve is surgically decompressed at the entrance to the meatal foramen where the labyrinthine segment and geniculate ganglion reside (4)[A].
  • Decompression surgery should not be performed >14 days after the onset of paralysis because severe degeneration of the facial nerve is likely irreversible after 2–3 weeks (4)[A].

Ongoing Care

Follow-Up Recommendations

Patient Monitoring

  • Patients should start treatment immediately and be followed for 12 months.
  • Patients who do not recover complete facial nerve function should be referred to an ophthalmologist for tarsorrhaphy.


No restrictions


  • Most achieve complete spontaneous recovery within 2 weeks (5)[A]
  • 85% of untreated patients will experience the 1st signs of recovery within 3 weeks of onset (8)[C].
  • Over 80% recover within 3 months (5)[A].
  • 16% are left with a partial palsy, motor synkinesis, and autonomic synkinesis (3)[A].
  • 5% experience severe sequelae, and a small number of patients experience permanent facial weakness and dysfunction (3)[A].
  • Poor prognostic factors include:
    • Age >60 years
    • Complete facial weakness
    • HTN
    • Ramsay-Hunt syndrome
  • Absence of recovery at 3 weeks


  • Corneal abrasion or ulceration
  • Steroid-induced psychological disturbances; avascular necrosis of the hips, knees, and/or shoulders
  • Steroid use can unmask subclinical infection (e.g., TB)


1. Worster A, Keim SM, Sahsi R, Pancioli AM, Best Evidence in Emergency Medicine (BEEM) Group et al. Do either corticosteroids or antiviral agents reduce the risk of long-term facial paresis in patients with new-onset Bell’s palsy? J Emerg Med. 2010;38:518–23.

2. De Diego-Sastre JI, Prim-Espada MP, Fernández García F. [The epidemiology of Bell's palsy] Rev Neurol. 2005;41:287–90.

3. Holland NJ, et al. Recent developments in Bell’s palsy. Br Med J. 2004;329:553–7.

4. Gilden DH. Clinical practice. Bell’s Palsy. N Engl J Med. 2004;351:1323–31.

5. Holten KB. How should we manage Bell’s palsy? J Fam Pract. 2004;53:797–8.

6. Salinas RA, Alvarez G, Daly F, Ferreira J et al. Corticosteroids for Bell’s palsy (idiopathic facial paralysis). Cochrane Database Syst Rev. 2010;3:CD001942.

7. Lockhart P, Daly F, Pitkethly M, Comerford N, Sullivan F et al. Antiviral treatment for Bell’s palsy (idiopathic facial paralysis). Cochrane Database Syst Rev. 2009;CD001869.

8. Peitersen E. The natural history of Bell’s palsy. Am J Otol. 1982;4(2):107–11.

9. Madhok V, Falk G, Fahey T, et al. Prescribe prednisolone alone for Bell’s palsy diagnosed within 72 hours of symptom onset. BMJ. 2009;338:b255.

10. Teixeira LJ, et al. Physical therapy for Bell’s palsy (idiopathic facial paralysis). Cochrane Database Syst Rev. 2008;16(3):CD006283.

11. Alakram P, Puckree T et al. Effects of electrical stimulation on House-Brackmann scores in early Bell’s palsy. Physiother Theory Pract. 2010;26:160–6.

Additional Reading

See Also (Topic, Algorithm, Electronic Media Element)

Amyloidosis; Herpes Simplex; Herpes Zoster; Sarcoidosis; Amyloidosis; Lyme Disease; Diabetes Mellitus Type 1; Diabetes Mellitus Type 2; Ramsay-Hunt Syndrome; Sjögren Syndrome; Melkersson-Rosenthal Syndrome



351.0 Bell’s palsy


193093009 Bell’s palsy (disorder)

Clinical Pearls

  • Steroids must be initiated immediately after onset of symptoms.
  • Look closely at the voluntary movement on the upper part of the face on the affected side; in Bell palsy, all of the muscles are involved (weak or paralyzed), whereas in a stroke, the upper muscles are spared (due to bilateral innervation).
  • Remember to protect the affected eye with lubrication and taping.
  • In areas with endemic Lyme disease, Bell palsy should be considered to be Lyme disease until proven otherwise.

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