AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Acknowledgments
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Acknowledgments
• Multimedia
• References

Background

Bell palsy is one of the most common neurologic disorders affecting the cranial nerves. It is an abrupt, unilateral, peripheral facial paresis or paralysis without a detectable cause. This syndrome of idiopathic facial paralysis was first described more than a century ago by Sir Charles Bell, yet much controversy still surrounds its etiology and management. Bell palsy is certainly the most common cause of facial paralysis worldwide.

Keeping in mind that Bell palsy is a diagnosis of exclusion is imperative. Other disease states or conditions that present with facial palsies are often misdiagnosed as idiopathic.

Patients with Bell palsy frequently present to the ED before seeing any other health care professional. The appearance of a distorted face and the abrupt functional impairment are the driving forces that prompt emergency evaluation. Patients often fear they have had a stroke or have a tumor and that their distorted facial appearance will be permanent.

The role of the ED consists of the following:

• Exclude other causes of facial paralysis.
• Initiate appropriate treatment.
• Protect the eye.
• Arrange appropriate medical follow-up care.

For related CME/CE activities, see CME/CE - Evidence-Based Management of Bell's Palsy: A Best Evidence Review and CME - Prednisolone Significantly Improves Recovery in Bell's Palsy.

Pathophysiology

Actual pathophysiology is unknown; this is an area of interminable debate. A popular theory champions inflammation of the facial nerve. During this process, the nerve increases in diameter and becomes compressed as it courses through the temporal bone.

The facial nerve courses through a portion of the temporal bone commonly referred to as the facial canal. The first portion of the facial canal (the labyrinthine segment) is narrowest. The tiny opening (about 0.66 mm in diameter) in this segment is known as the meatal foramen.

The facial nerve is subjected to tight confines on its journey through the facial canal. It seems logical that various inflammatory, demyelinating, ischemic, or compressive processes may impair neural conduction at this unique anatomic site.

Anatomy

The facial nerve (seventh cranial nerve) has 2 components. The larger portion comprises efferent fibers that stimulate the muscles of facial expression. The smaller portion contains taste fibers to the anterior two thirds of the tongue, secretomotor fibers to the lacrimal and salivary glands, and some pain fibers.

Pathway

The path of the facial nerve is very complex; this may be the reason the nerve is vulnerable to injury. Two portions of the facial nerve leave the brain at the cerebellopontine angle, traverse the posterior cranial fossa, dive into the internal acoustic meatus, pass through the facial canal in the temporal bone, then angle sharply backwards, where they pass behind the middle ear and exit the cranium at the stylomastoid foramen. From here, the facial nerve bisects the parotid gland, and then terminal branches burst out from the parotid plexus to supply the muscles of facial expression.

Frequency

United States

The incidence of Bell palsy in the United States is approximately 23 cases per 100,000 persons. The condition affects approximately 1 person in 65 in a lifetime.

International

The incidence is the same as in the United States.

Mortality/Morbidity

Bell palsy can cause aesthetic, functional, and psychological disturbances in patients who have residual nerve dysfunction during their recovery phase or in patients with incomplete healing.

• Partial paralysis
• Motor synkinesis (involuntary movement accompanying a voluntary movement)
• Autonomic synkinesis (involuntary lacrimation after a voluntary muscle movement)

Race

Incidence of Bell palsy appears to be slightly higher in persons of Japanese descent.

Sex

No difference exists in sex distribution in patients with Bell palsy.

Age

Age affects the probability of contracting Bell palsy. The incidence is highest in persons aged 15-45 years. Bell palsy is less common in those younger than 15 years and in those older than 60 years.

CLINICAL

Section 3 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Acknowledgments
• Multimedia
• References

History

Most patients presenting to the ED suspect they have suffered a stroke or have an intracranial tumor. The most common complaint is of weakness on one side of their face.

• Postauricular pains: Almost 50% of patients experience pain in the mastoid region. The pain frequently occurs simultaneously with the paresis, but precedes the paresis by 2-3 days in about 25% of patients.
• Tear flow: Two thirds of patients complain about tear flow. This is due to the reduced function of the orbicularis oculi in transporting the tears. Fewer tears arrive at the lacrimal sac and overflow occurs. The production of tears is not accelerated.
• Altered taste: While only one third of patients complain about taste disorders, four fifths of patients show a reduced sense of taste. This may be explained by only half the tongue being involved.
• Dry eyes
• Hyperacusis: Impaired tolerance to typical levels of noise due to an increased irritability to the sensory neural mechanism.

Physical

Findings of facial paralysis are easily recognizable on physical examination. A careful, complete examination excludes other possible causes of facial paralysis. Strongly consider other etiologies if all branches of the facial nerve are not affected.

• The classic definition of Bell palsy describes mononeuric involvement of the facial nerve, yet other cranial nerves are probably affected. The facial nerve is the only cranial nerve eliciting obvious findings on physical examination because of its unique anatomical course from the brain to the lateral face.
• Remember that weakness and/or paralysis from involvement of the facial nerve manifests as weakness of the entire face (upper and lower) on the affected side. Focus attention on the voluntary movement of the upper part of the face on the affected side.
• In supranuclear lesions such as a cortical stroke (upper motor neuron; above the facial nucleus in the pons), the upper third of the face is spared while the lower two thirds are paralyzed. The orbicularis, frontalis, and corrugator muscles are innervated bilaterally, which explains the pattern of facial paralysis.
• Test other cranial nerves; their examination results should be normal.
• Tympanic membranes should not be inflamed; presence of infection raises possibility of complicated otitis media.

Causes

"All that glitters is not gold" (William Shakespeare)

The etiology of Bell palsy remains unclear, although vascular, infectious, genetic, and immunologic causes have all been proposed. Patients with other diseases or conditions sometimes develop a peripheral facial nerve palsy, but these are not classified as Bell palsy (see Differentials).

• Viral infections: Clinical and epidemiologic data lend credence to an infectious origin, which triggers an immunologic response, resulting in damage to the facial nerve. Pathogens leading the list include herpes simplex virus type 1 (HSV-1); herpes simplex virus type 2 (HSV-2); human herpesvirus (HHV); varicella-zoster virus (VZV); Mycoplasma pneumoniae; Borrelia burgdorferi; influenza B; adenovirus; coxsackievirus; Ebstein-Barr virus; hepatitis A, B, and C; cytomegalovirus (CMV); and rubella virus.
• Pregnancy: Bell palsy is uncommon in pregnancy; however, the prognosis is significantly worse in pregnant women with Bell palsy than among nonpregnant women with palsy.
• Genetics: Recurrence rates (4.5-15%) and familial incidence (4.1%) have been addressed in various studies. Genetics may have a role in Bell palsy, but which factors are inherited is unclear.

DIFFERENTIALS

Section 4 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Acknowledgments
• Multimedia
• References

Other Problems to be Considered

Herpes zoster
Ramsey-Hunt syndrome
Zoster sine herpete
Pregnancy (especially third trimester)
Polyneuritis
Acute otitis
Chronic otitis
Temporal bone fracture
Infectious mononucleosis
Parotid tumors
Sarcoidosis
Cholesteatoma of the middle ear
Aneurysm of vertebral, basilar artery, or carotid arteries
Carcinomatous meningitis
Facial trauma (blunt, penetrating, iatrogenic)
Leukemic meningitis
Leprosy
Melkersson-Rosenthal syndrome
Middle ear surgery
Osteomyelitis of the skull base
Skull base tumor

WORKUP

Section 5 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Acknowledgments
• Multimedia
• References

Lab Studies

• No specific laboratory tests exist to confirm the diagnosis of Bell palsy. Clinical setting determines tests that may be of value. Other potential causes in the differential diagnosis may be confirmed or suspected based on the following diagnostic laboratory tests:
• • Complete blood count
  • Erythrocyte sedimentation rate
  • Thyroid function studies
  • Lyme titer
  • Serum glucose level
  • Rapid plasma reagin (RPR) or Venereal Disease Research Laboratory (VDRL) test
  • Human immunodeficiency virus (HIV)
  • Cerebral spinal fluid analysis
  • Immunoglobulin M (IgM), immunoglobulin G (IgG), and immunoglobulin A (IgA) titers for CMV, rubella, HSV, hepatitis A, hepatitis B, hepatitis C, VZV, M pneumoniae, and B burgdorferi.

Imaging Studies

• Bell palsy remains a clinical diagnosis. Imaging studies are not indicated in the ED. Excluding other causes of facial palsy may require one of the following imaging studies depending on clinical setting.
• • Facial CT scan or plain radiographs: Perform to rule out fractures or bony metastasis.
  • CT scan is indicated when stroke, or acquired immunodeficiency syndrome (AIDS)-CNS involvement is considered in differential diagnosis
  • MRI: For a suspected neoplasm of the temporal bone, brain, parotid gland, or other structure, or to evaluate for multiple sclerosis, MRI is the superior method of imaging. The course of the facial nerve through the intratemporal and extratemporal regions from the brain to the facial muscles and glands can be followed on MRI. MRI also may be considered in lieu of CT scan.

Other Tests

• Electrodiagnosis of the facial nerve: These studies assess the function of the facial nerve. These tests are rarely performed on an emergent basis.
• • Electromyography (EMG) and nerve conduction velocities produce a graphic readout of the electrical currents displayed by stimulating the facial nerve and recording the excitability of the facial muscles it supplies. Comparison to the contralateral side helps determine the extent of nerve injury and has prognostic implications. This is not part of the acute workup.
  • In the nerve excitability test, the threshold of the electrical stimulus producing visible muscle twitching is determined.
  • Electroneurography (ENoG) compares evoked potentials on the paretic side versus the healthy side.

TREATMENT

Section 6 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Acknowledgments
• Multimedia
• References

Emergency Department Care

The primary treatment of patients with Bell palsy in the ED is pharmacologic management. The remainder of care focuses on reassurance, eye care instructions, and appropriate follow-up care.

• Steroids
• • Treatment of Bell palsy with steroids remains controversial. Numerous small studies have shown conflicting results using steroids in treating Bell palsy. However, a recent randomized controlled trial showed significant improvement in outcomes with the use of steroids.
  • Experts suggest using steroids as a means to optimize outcomes. Once the decision to use steroids is made, the consensus is to start immediately.
• Antiviral agents: Although there is insufficient research evaluating the efficacy of antiviral medicines in Bell palsy, most experts believe in a viral etiology. Therefore, antiviral agents seem a logical choice for pharmacologic management and are commonly recommended.
• Eye care: The eyes are frequently unprotected in patients with Bell palsy. This leaves the eyes at risk for corneal drying and foreign body exposure. Manage with tear substitutes, lubricants, and eye protection.
• • Artificial tears: Use these during waking hours to replace diminished or absent lacrimation.
  • Lubricants are used during sleep. They may be used during waking hours if artificial tears cannot provide adequate protection. One disadvantage is blurred vision during waking hours.
  • Eyeglasses or shields protect the eye from injury and reduce drying by decreasing the air currents that come directly in contact with the exposed cornea.

Consultations

The patient's primary care provider or consultant should provide close follow-up care. Documentation should chart the progress of the patient's recovery.

Opinions widely vary on referral to a specialist. Some specific referral indications are listed below:

• Neurologist: When other neurologic signs are identified on physical examination and for an atypical presentation of Bell palsy, referral is indicated.
• Ophthalmologist: For any unexplained ocular pain or abnormal findings on physical examination of the eyes, the patient should be referred for further workup.
• Otolaryngologist: In patients with persistent paralysis, prolonged weakness of the facial muscles, or recurrent weakness, referral is warranted.
• Surgeon: Surgery to decompress the facial nerve is recommended occasionally for patients with Bell palsy. Patients with a poor prognosis identified by facial nerve testing or persistent paralysis appear to benefit the most from surgical intervention.

MEDICATION

Section 7 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Acknowledgments
• Multimedia
• References

Management may not require medication because most patients recover without medicine. This watchful waiting plan is an option; however, some individuals with Bell palsy never completely recover. Both medications listed below have clinical trials that support and dispute their efficacy.

Drug Category: Corticosteroids

Have anti-inflammatory properties and cause profound and varied metabolic effects. Modify the body's immune response to diverse stimuli.

Drug Category: Antivirals

Herpes simplex infections may be a common cause of Bell palsy. Acyclovir is the most-used treatment, but other antiviral agents may be appropriate.
Valacyclovir is a prodrug of acyclovir and produces 3-5 times the blood levels of acyclovir than oral Zovirax.

FOLLOW-UP

Section 8 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Acknowledgments
• Multimedia
• References

In/Out Patient Meds

• Consider prednisone at an initial dose of 1 mg/kg/d up to 60 mg.
• • Prednisone is a potent drug with a potential for side effects. Older studies are mixed in showing efficacy. A recent double-blinded, randomized controlled trial showed benefit if administered within 72 hours.¹
  • If a decision is made to administer steroids in patients without contraindications, the best choice is a short burst of prednisone up to 10 days. (Steroid taper may also be used.)
• Consider using antivirals within 72 hours.
• • Administer acyclovir (Zovirax) 800 mg PO 5 times/d for 10 d; 20 mg/kg in patients younger than 2 years. Recent evidence supports HSV as a major cause of Bell palsy. However, evidence showing efficacy with acyclovir has been mixed.
  • Valacyclovir (Valtrex) 500 mg PO twice a day for 5 days may be used instead. Although more expensive, this may lead to better compliance than acyclovir. If VZV is the cause, higher doses may be needed (1000 mg PO tid). However, because of increased cost and increased risk of side effects, this cannot be routinely recommended at this time.

Complications

• Most patients with Bell palsy recover without any cosmetically obvious deformities; however, approximately 5% are left with an unacceptably high degree of sequelae.
• Incomplete motor regeneration
• • The largest portion of the facial nerve comprises efferent fibers that stimulate muscles of facial expression. If the motor portion achieves suboptimal regeneration, paresis of all or some of these facial muscles results.
  • This manifests as (1) oral incompetence, (2) epiphora (excessive tearing), and (3) nasal obstruction.
• Incomplete sensory regeneration
• • Dysgeusia (impairment of taste) may result.
  • Ageusia (loss of taste) may result.
  • Dysesthesia (impairment of sensation or disagreeable sensation to normal stimuli) may result.
• Aberrant reinnervation of the facial nerve
• • After the impaired neural conduction of the facial nerve begins the regeneration and repair process, some nerve fibers take an unusual course and connect to neighboring fibers. This aberrant reconnection produces unusual neurologic pathways.
  • When voluntary movements are initiated, they are accompanied by involuntary movements (eg, the movement of a closed eye following that of the uncovered one). These involuntary movements accompanying voluntary movement are termed synkinesis.

Prognosis

• The natural course of Bell palsy varies from early complete recovery to substantial nerve injury with permanent sequelae. Prognostically, patients fall into 3 groups with roughly equal numbers in each group.
• • Group 1 regains complete recovery of facial motor function without sequelae.
  • Group 2 experiences incomplete recovery of facial motor function, but no cosmetic defects are apparent to the untrained eye.
  • Group 3 experiences permanent neurologic sequelae that are cosmetically and clinically apparent.
• Most patients develop an incomplete facial paralysis during the acute phase. This group has an excellent prognosis for full recovery. Patients demonstrating complete paralysis are at higher risk for severe sequelae.
• Of patients with Bell palsy, 85% achieve complete recovery. Ten percent are bothered by some asymmetry of facial muscles, while 5% experience severe sequelae.

Patient Education

• Eye care
• • Protect the eye from foreign objects and sunlight.
  • Keep the eye well lubricated.
  • Educate the patient to report new ocular findings such as pain, discharge, or visual changes.
• For excellent patient education resources, visit eMedicine's Brain and Nervous System Center. Also, see eMedicine's patient education article Bell Palsy.

ACKNOWLEDGMENTS

Section 9 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Acknowledgments
• Multimedia
• References

The authors and editors of eMedicine gratefully acknowledge the contributions of previous author, Michael Lambert, MD, to the development and writing of this article.

MULTIMEDIA

Section 10 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Acknowledgments
• Multimedia
• References

Media file 1:  The facial nerve.
	View Full Size Image
Media type:  Image

REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Acknowledgments
• Multimedia
• References

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Article Last Updated: Apr 9, 2008