eMedicine Specialties > Emergency Medicine > Neurology

Bell Palsy: Differential Diagnoses & Workup

Author: Bruce Lo, MD, Medical Director, Sentara Norfolk General Hospital; Assistant Professor, Assistant Program Director, Core Academic Faculty, Department of Emergency Medicine, Eastern Virginia Medical School
Contributor Information and Disclosures

Updated: Oct 27, 2009

Differential Diagnoses

Diabetes Mellitus, Type 1 - A Review
Diabetes Mellitus, Type 2 - A Review
Fractures, Mandible
Herpes Zoster
Multiple Sclerosis
Tick-Borne Diseases, Lyme

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
Guillain-Barre

Workup

Laboratory Studies

  • No specific laboratory tests exist to confirm the diagnosis of Bell's palsy. Clinical setting determines tests that may be of value. Results of the following laboratory tests may confirm or suggest other potential causes in the differential diagnosis:
    • 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) antibodies
    • Cerebral spinal fluid analysis
    • Immunoglobulin M (IgM), immunoglobulin G (IgG), and immunoglobulin A (IgA) titers for CMV; rubella; HSV; hepatitis A virus; hepatitis B virus; hepatitis C virus; VZV; M pneumoniae; and Borrelia burgdorferi

Imaging Studies

  • Bell's 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: Perform when the differential diagnosis includes stroke or CNS involvement from acquired immunodeficiency syndrome (AIDS).
    • MRI: Perform in patients with a suspected neoplasm of the temporal bone, brain, parotid gland, or other structure, or to evaluate for multiple sclerosis. MRI can visualize the course of the facial nerve through the intratemporal and extratemporal regions from the brain to the facial muscles and glands. 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.10
    • 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.
    • The nerve excitability test determines the threshold of the electrical stimulus needed to produce visible muscle twitching.
    • Electroneurography (ENoG) compares evoked potentials on the paretic side versus the healthy side.

More on Bell Palsy

Overview: Bell Palsy
Differential Diagnoses & Workup: Bell Palsy
Treatment & Medication: Bell Palsy
Follow-up: Bell Palsy
Multimedia: Bell Palsy
References
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References

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Further Reading

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Contributor Information and Disclosures

Author

Bruce Lo, MD, Medical Director, Sentara Norfolk General Hospital; Assistant Professor, Assistant Program Director, Core Academic Faculty, Department of Emergency Medicine, Eastern Virginia Medical School
Bruce Lo, MD is a member of the following medical societies: American College of Emergency Physicians, Emergency Medicine Residents Association, Medical Society of Virginia, Norfolk Academy of Medicine, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Medical Editor

Edward Bessman, MD, Chairman, Department of Emergency Medicine, John Hopkins Bayview Medical Center; Assistant Professor, Department of Emergency Medicine, Johns Hopkins University
Edward Bessman, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

J Stephen Huff, MD, Associate Professor, Emergency Medicine and Neurology, Department of Emergency Medicine, University of Virginia Health Sciences Center
J Stephen Huff, MD is a member of the following medical societies: American Academy of Emergency Medicine, American Academy of Neurology, American College of Emergency Physicians, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Rick Kulkarni, MD, Assistant Professor of Surgery, Section of Emergency Medicine, Yale-New Haven Hospital
Rick Kulkarni, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: WebMD Salary Employment

 
 
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