BELL PALSY

Irina Pechenko, MD

 BASICS

DESCRIPTION

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

EPIDEMIOLOGY

•  Affects 0.02% of the population annually

•  Predominant sex: male = female

•  Median age of onset is 40 years but affects all ages.

•  Accounts for 60–75% of all cases of unilateral facial paralysis

•  Occurs with equal frequency on the left and right sides of the face

•  Most patients recover, but as many as 30% are left with facial disfigurement and pain.

Incidence

•  20 to 30 cases per 100,000 people in the United States per year

•  Lowest in children ≤10 years of age; highest in adults ≥70 years of age

•  Higher among pregnant women

Prevalence

Affects 40,000 Americans every year

ETIOLOGY AND PATHOPHYSIOLOGY

•  Results from damage to the facial cranial nerve (VII)

•  Inflammation of cranial nerve VII causes swelling and subsequent compression of both the nerve and the associated vasa nervorum.

•  May arise secondary to reactivation of latent herpesvirus (herpes simplex virus [HSV] type 1 and herpes zoster virus) in cranial nerve ganglia or due to ischemia from arteriosclerosis associated with diabetes mellitus

Genetics

May be associated with a genetic predisposition, but it remains unclear which factors are inherited

RISK FACTORS

•  Pregnancy, specially associated with severe preeclampsia

•  Diabetes mellitus

•  Age >30 years

•  Exposure to cold temperatures

•  Upper respiratory infection (e.g., coryza, influenza)

•  Chronic HTN

•  Obesity

•  Migraine headache

•  Narrow diameter of facial canal (1)

COMMONLY ASSOCIATED CONDITIONS

•  HSV

•  Lyme disease

•  Diabetes mellitus

•  Hypertension

•  Herpes zoster virus

•  Ramsay-Hunt syndrome

•  Sjögren syndrome

•  Sarcoidosis

•  Eclampsia

•  Amyloidosis

 DIAGNOSIS

HISTORY

•  Time course of the illness (rapid onset)

•  Predisposing factors: recent viral infection, tick bite, 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, which may precede the palsy in 25% of cases

•  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 caused by 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

  Impaired ability to smile, grin, or purse the lips

  Bell phenomenon: upward diversion of the eye with attempted closure of the lid

–  Patients may complain of numbness, but no deficit is present on sensory testing.

–  Examine for involvement of other cranial nerves.

•  Head, ears, eyes, nose, and throat

–  Carefully examine to exclude a space-occupying lesion.

–  Perform pneumatic otoscopic exam.

•  Skin: Examine for erythema migrans (Lyme disease) and vesicular rash (herpes zoster virus).

DIFFERENTIAL DIAGNOSIS

Etiologies include the following:

•  Infectious

–  Acute or chronic otitis media

–  Malignant otitis externa

–  Osteomyelitis of the skull base

–  Lyme disease (common)

•  Cerebrovascular

–  Brainstem stroke involving anteroinferior cerebellar artery

–  Aneurysm involving carotid, vertebral, or basilar arteries

•  Neoplastic (Onset of palsy is usually slow and progressive and accompanied by additional cranial nerve deficits and/or headache.)

–  Tumors of the parotid gland

–  Cholesteatoma

–  Skull base tumor

–  Carcinomatous meningitis

–  Leukemic meningitis

•  Traumatic

–  Temporal bone fracture

–  Mandibular bone fracture

•  Other

–  Multiple sclerosis

–  Myasthenia gravis (should be considered in cases of recurrent or bilateral facial palsy)

–  Guillain-Barré syndrome (may also present with bilateral facial palsy)

–  Sjögren syndrome

–  Sarcoidosis

–  Amyloidosis

–  Melkersson-Rosenthal syndrome

–  Mononeuritis or polyneuritis

DIAGNOSTIC TESTS & INTERPRETATION

Initial Tests (lab, imaging)

•  Blood glucose level (if diabetes a consideration)

•  Lyme titer, ELISA, and Western blot for immunoglobulin (Ig) M, IgG for Borrelia burgdorferi

•  Consider CBC, ESR.

•  Consider rapid plasma reagin test.

•  Consider HIV test.

•  In appropriate clinical circumstances, consider titers for varicella-zoster virus, cytomegalovirus, rubella, hepatitis A, hepatitis B, and hepatitis C.

•  Procalcitonin level may predict severity and prognosis of Bell palsy.

Follow-Up Tests & Special Considerations

•  CSF analysis

–  CSF protein is elevated in 1/3 of cases.

–  CSF cells show mild elevation in 10% of cases with a mononuclear cell predominance.

–  Not routinely indicated

•  Salivary polymerase chain reaction for HSV1 or herpes zoster virus (largely reserved for research purposes)

•  Facial radiographs

–  In the setting of trauma, evaluate for fracture.

•  IV contrast–enhanced head CT

–  Evaluate for fracture.

–  Evaluate for stroke, if stroke is in the differential.

•  IV contrast–enhanced brain MRI

–  Evaluate for central pontine, temporal bone, and parotid neoplasms.

–  Not routinely indicated

Diagnostic Procedures/Other

•  Electromyograph: Nerve conduction on affected and nonaffected sides can be compared to determine the extent of nerve injury, especially if there is dense palsy or no recovery after several weeks.

•  Electroneurography: Evoked potentials of affected and nonaffected sides can be compared.

•  MRI-CT combined or 3D modeling: may be used in the future for evaluation of facial canal diameter (1)[B].

Test Interpretation

Invasive diagnostic procedures are not indicated because biopsy could further damage cranial nerve XII.

 TREATMENT

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.

MEDICATION

•  Corticosteroids decrease inflammation and limit nerve damage, thereby reducing the number of patients with residual facial weakness.

•  Routine use of antiviral medication is not recommended. Antiviral agents targeting herpes simplex, when administered concurrently with corticosteroids, may further reduce the risk of unfavorable outcomes in patients with a dense Bell palsy:

–  Antivirals alone are less likely to produce full recovery than corticosteroids.

–  A combination of valacyclovir and steroids provides only minimal added benefit over steroid use alone (2)[B].

•  Corticosteroids

–  Prednisolone: total of 500 mg over 10 days, 25 mg PO BID

  Treatment with prednisolone within 48 hours of palsy onset has shown higher complete recovery rates and less synkinesis compared with no prednisolone.

  Antivirals in combination with corticosteroids

  Valacyclovir: 1,000 mg TID for 7 days plus prednisolone 60 mg/day for 5 days; then tapered by 10 mg/day for total treatment length of 10 days (2)[B]

  Steroids are recommended for all cases of Bell palsy.

  Controversial whether antiviral treatment is necessary with steroids

  American Academy of Otolaryngology–Head and Neck Surgery recommends antiviral treatment in all cases of Bell palsy cases (3)[A].

  There is a strong recommendation to use corticosteroids for all patients with Bell palsy and strong recommendation against use of antiviral treatment alone (3)[A].

•  Contraindications

–  Documented hypersensitivity

–  Preexisting infections, including tuberculosis (TB) and systemic mycosis

•  Precautions: Use with discretion in pregnant patients and those with 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 during pregnancy; consult with an obstetrician.

ISSUES FOR REFERRAL

Patients may need to be referred to an ear, nose, and throat specialist or a neurologist.

ADDITIONAL THERAPIES

•  Physical therapy: strong evidence that physical therapy combined with drug treatment has positive effect on grade and time of recovery compared with drug treatment only (4,5)[A].

•  Electrostimulation and mirror biofeedback rehabilitation have limited evidence of effect.

•  Acupuncture with strong stimulation has shown some therapeutic promise.

•  Routine use of eye-protective measures for patients with incomplete eye closure is recommended (3)[A].

SURGERY/OTHER PROCEDURES

•  Surgical treatment of Bell palsy remains controversial and is reserved for intractable cases.

•  There is insufficient evidence to decide whether surgical intervention is beneficial or harmful in the management of Bell palsy.

•  In those cases where surgical intervention is performed, cranial nerve XII is surgically decompressed at the entrance to the meatal foramen where the labyrinthine segment and geniculate ganglion reside.

•  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 to 3 weeks.

•  A routine surgical decompression is not recommended (2)[B].

 ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Patient Monitoring

•  Patients should start steroid 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.

PATIENT EDUCATION

American Academy of Family Physicians: http://www.aafp.org/afp/2007/1001/p1004.html

PROGNOSIS

•  Most patients achieve complete spontaneous recovery within 2 weeks. >80% recover within 3 months.

•  85% of untreated patients will experience the first signs of recovery within 3 weeks of onset.

•  16% are left with a partial palsy, motor synkinesis, and autonomic synkinesis.

•  5% experience severe sequelae, and a small number of patients experience permanent facial weakness and dysfunction.

•  Poor prognostic factors include the following:

–  Age >60 years

–  Complete facial weakness

–  Hypertension

–  Ramsay-Hunt syndrome

•  The Sunnybrook and House-Brackmann facial grading systems are clinical prognostic models that identify Bell palsy patients at risk for nonrecovery at 12 months.

•  Treatment with prednisolone or no prednisolone and the Sunnybrook score are significant factors for predicting nonrecovery at 1 month.

•  Patients with no improvement or progression of symptoms should be referred to ENT (3)[A] and may require neuroimaging to rule out neoplasms (3)[A].

COMPLICATIONS

•  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).

REFERENCES

1.  Kilicaslan S, Uluyol S, Gur MH, et al. Diagnostic and prognostic value of procalcitonin levels in patients with Bell’s palsy. Eur Arch Otorhinolaryngol. 2016;273(6):1615–1618.

2.  Worster A, Keim SM, Sahsi R, 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(4):518–523.

3.  de Almeida JR, Guyatt GH, Sud S, et al. Management of Bell palsy: clinical practice guideline. CMAJ. 2014;186(12):917–922.

4.  Teixeira LJ, Valbuza JS, Prado GF. Physical therapy for Bell’s palsy (idiopathic facial paralysis). Cochrane Database Syst Rev. 2011;(12):CD006283.

5.  Ferreira M, Marques EE, Duarte JA, et al. Physical therapy with drug treatment in Bell palsy: a focused review. Am J Phys Med Rehabil. 2015;94(4):331–340.

 SEE ALSO

Amyloidosis; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Herpes Simplex; Herpes Zoster (Shingles); Lyme Disease; Sarcoidosis; Sjögren Syndrome

 CODES

ICD10

G51.0 Bell’s palsy

CLINICAL PEARLS

•  Initiate steroids immediately following the 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 (because of bilateral innervation).

•  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.