Bell Palsy (Idiopathic Facial Paralysis) Case File

Bell Palsy (Idiopathic Facial Paralysis) Case File

Eugene C. Toy, MD, Barry C. Simon, MD, Terrence H. Liu, MD, MHP, Katrin Y. Takenaka, MD, Adam J. Rosh, MD, MS

Case 25

A 27-year-old woman notice that since 1 day ago, she has noticed that her mouth has been drooping in the right corner, and it is difficult for her to drink water without drooling. She cannot close her right eye completely, and her right eye is red and irritated. She denies having headaches, visual disturbances, nausea, or vomiting. She does not have any history of trauma. Her past medical history is unremarkable. She is not taking any medications. Her mother had a stroke when she was 60 years old. The patient states that she is from Michigan and has not been traveling recently. On physical examination, the right corner of her mouth droops, and the right nasolabial fold is absent. The right lower eyelid is sagging, and the patient cannot completely close her right eye. On attempts to close the right eye, the eye rolls upward. The patient also cannot wrinkle her forehead. The other cranial nerves seem to be normal, and the neurologic examination reveals no deficits other than as stated.

⯈ What is your diagnosis?

⯈ How will you manage this condition?

ANSWER TO CASE 25:

Bell Palsy (Idiopathic Facial Paralysis)

Summary: A 27-year-old woman has acute onset of right facial weakness and right eye irritation. She denies trauma and has no other cranial nerve or neurological problems.

• Most Likely Diagnosis: Facial nerve palsy most likely idiopathic (Bell palsy)
• Management of condition: Protection of the eye and a course of prednisone

ANALYSIS

Objectives

1. Differentiate an upper motor neuron process from a lower motor neuron process and review the differential diagnoses for each.
2. Understand the clinical presentation of Bell palsy.
3. Learn the management of Bell palsy.

Considerations

This 27-year-old woman is affected by the abrupt onset of right facial weakness. Notably, her upper facial muscles are affected, which is consistent with a peripheral neuropathy. She has none of the findings suggestive of a more complicated process (Table 25–1). Her symptoms are likely caused by paralysis of the seventh cranial nerve, which is mainly a motor nerve supplying all the ipsilateral muscles of facial expression. The drooping of the right corner of the mouth represents paralysis of the orbicularis oris muscle. Tearing of the right eye (epiphora) occurs because paralysis of the orbicularis oculi muscle prevents closure of the eyelids and causes the lacrimal duct opening to sag away from the conjunctiva. The inability to wrinkle the forehead is a result of paralysis of the frontalis muscle. Affected individuals will often have the Bell phenomenon upon attempted closure of the eyelids, the eye on the paralyzed side rolls upward.

Approach To:

Facial Paralysis

Approach to Bell Palsy The seventh cranial nerve exits the cranium through the stylomastoid foramen and supplies all the muscles concerned with facial expression. It also has a small

sensory component which conveys taste sensation from the anterior two-thirds of the tongue and cutaneous impulses from the anterior wall of the external auditory meatus. A complete interruption of the facial nerve at the stylomastoid foramen paralyzes all the muscles of the face on the affected side. Taste sensation is intact because the lesion is beyond the site where the chorda tympani has separated from the main trunk of the facial nerve. If the nerve to the stapedius muscle is involved, there is often hyperacusis. If the geniculate ganglion or the motor root proximal to it is involved, lacrimation and salivation may be reduced.

Although the most common cause of facial paralysis is Bell palsy, this is a diagnosis of exclusion. In other words, the emergency department (ED) physician should be careful of presuming a facial palsy is Bell palsy without considering other possible etiologies. Other causes of nuclear or peripheral facial nerve palsy include Lyme disease, tumors of the temporal bone (carotid body, cholesteatoma, dermoid), Ramsey Hunt syndrome (herpes zoster of the geniculate ganglion), and acoustic neuromas. Malignant otitis externa, stroke, Guillain-Barré disease, polio, sarcoid, and human immunodeficiency virus (HIV) infection are other processes that must be considered.

All forms of peripheral facial nerve palsy must be distinguished from the supranuclear type. In the latter, the frontalis and orbicularis oculi muscles are spared because the innervation of the upper facial muscles is bilateral and that of the lower facial muscles is mainly contralateral. In other words, if the patient has drooping of the mouth but is able to wrinkle his or her forehead normally, an intracranial process should be suspected. With supranuclear lesions, there may also be a dissociation of emotional and voluntary facial movements. Because Bell palsy is a diagnosis of exclusion, a very careful history and physical examination are critical to detect any other neurological abnormalities.

The onset of Bell palsy is abrupt, and symptoms can progress from weakness to complete paralysis over a week. Over half of the patients with Bell palsy will recall a preceding viral prodrome. Associated symptoms may include pain behind the ear, ipsilateral loss of taste sensation, decreased or overflow tearing, and hyperacusis. The patient may complain of heaviness and numbness on the affected side of the face; however, no sensory loss is demonstrable. Eighty percent of patients recover within weeks to a few months. The presence of incomplete paralysis in the first week is the most favorable prognostic sign. If the presentation is atypical or there is no improvement at 6 months, laboratory studies, imaging studies (eg, computed tomography, magnetic resonance imaging), or motor-nerve conduction studies should be considered.

Treatment

The patient should use an eye patch while sleeping to protect the eye and prevent corneal drying and abrasions. While awake, he or she should apply artificial tears to the affected eye every hour. Massaging of the weakened muscles may improve muscle tone and aid in recovery.

Medical therapy should be started as soon as possible but can be considered for up to 1 week after the onset of symptoms. Although treatment regimens are controversial, most experts recommend the use of corticosteroids. Corticosteroids are hypothesized to decrease facial nerve edema. Thus prednisone 1 mg/kg/d can be given orally for 7 to 10 days (with or without a taper). Because some studies implicated herpes simplex virus as a causative agent of Bell palsy, antivirals were routinely incorporated into the treatment regimen. However, further studies have shown conflicting results regarding the efficacy of antiviral therapy. If physicians choose to prescribe antiviral agents, valacyclovir and famciclovir are favored due to their less frequent dosing and greater bioavailability. These agents do cost substantially more than acyclovir, which requires more frequent dosing. If medical therapy is unsuccessful, patients may benefit from surgical decompression of the facial nerve.

COMPREHENSION QUESTIONS

25.1 A 32-year-old woman complains of facial weakness for several weeks that has gradually worsened. The upper face and lower face are both affected. She does not have weakness of the arms or legs. Which of the following would suggest a diagnosis other than Bell palsy?

A. Absence of symptoms in arms

B. Absence of symptoms in legs

C. Gradual onset over several weeks

D. Upper facial weakness

25.2 A 55-year-old woman complains of weakness of her right facial muscles along with numbness of her right cheek region. Which of the following is the next step?

A. Obtain magnetic resonance imaging of the brain.

B. Obtain a rapid plasma reagin (RPR) serology.

C. Perform a lumbar puncture.

D. Recommend eye protection and observation.

Match the following mechanisms (A to E) to the clinical scenarios presented in Questions 25.3 to 25.5:

A. Pressure on the cerebellopontine nucleus

B. Edema of the nerve at the stylomastoid foramen

C. Immunoglobulins against the acetylcholine receptor

D. Multifocal myelin destruction in the central nervous system

E. Autoimmune attack on myelinated motor nerves particularly of the lower extremities

25.3 A 22-year-old woman is on the ventilator because of inability to breathe. This condition began 3 weeks ago when she had weakness of both legs following a bout of gastroenteritis. Her deep tendon reflexes are absent.

25.4 A 32-year-old woman has a 5-year history of progressive weakness during the day. She cannot look upward for long periods of time because of fatigue.

25.5 A 35-year-old man had eye weakness 2 years ago with full resolution. Now he has difficulty with his right handgrip. His deep tendon reflexes are normal to increased.

ANSWERS

25.1 C. The onset of Bell palsy is abrupt with maximum weakness occurring within 1 week. Facial nerve palsy due to tumors of the temporal bone is insidious, and the symptoms gradually progress.

25.2 A. The numbness over the cheek is concerning and inconsistent with Bell palsy. The facial nerve supplies all the muscles of the face. Injury to this nerve produces paralysis of the facial muscles. Drooping of the corner of the mouth is one of the findings. The tongue is supplied by the hypoglossal nerve. Middle ear lesions producing facial palsy will cause loss of taste over the anterior two-thirds of the tongue, but alteration of taste sensation does not occur. The sensory component of the facial nerve is limited to the anterior wall of the external auditory meatus. Further evaluation with magnetic resonance imaging (MRI) may be warranted.

25.3 E. This presentation of ascending paralysis is classic for Guillain-Barré syndrome, and typically the deep tendon reflexes are absent.

25.4 C. Myasthenia gravis is characterized by progressive weakness throughout the day, particularly involving the eye muscles. These symptoms are due to immunoglobulin G antibodies against the acetylcholine receptors.

25.5 D. Multiple sclerosis typically affects young individuals with waxing and waning weakness and full recovery between exacerbations. The mechanism is multifocal destruction of the myelin in the central nervous system.

CLINICAL PEARLS

⯈ Bell palsy is an idiopathic seventh cranial nerve peripheral neuropathy, leading to both upper and lower facial weakness.

⯈ The diagnosis of Bell palsy is one of exclusion.

⯈ The most important assessment in a patient who presents with possible Bell palsy is to rule out serious disorders such as intracranial tumors and strokes.

⯈ Protection of the eye to prevent corneal drying and abrasions is accomplished with an eye patch during sleep and lubricants to the affected eye.

⯈ The prognosis of Bell palsy is usually favorable, but persistent weakness, the appearance of other neurologic deficits, or blisters that appear on the ear are indications for referral.

References

Axelsson S, Lindberg S, Stjernquist-Desatnik A. Outcome of treatment with valacyclovir and prednisone in patients with Bell’s palsy. Ann Otol Rhinol Laryngol. 2003;112:197. 

Baringer JR. Herpes simplex virus and Bell’s palsy. Ann Intern Med. 1996;124:63. 

Benatar M, Edlow J. The spectrum of cranial neuropathy in patients with Bell’s palsy. Arch Intern Med. 2004;164:23-83. 

Brodal A. The cranial nerves. In: Neurological Anatomy in Relation to Clinical Medicine. 3rd ed. New York, NY: Oxford;1980:448-577. 

Engstrom M, Berg T, Stjernquist-Desatnik A, et al. Prednisolone and valaciclovir in Bell’s palsy: a randomised, double-blind, placebo-controlled, multicentre trial. Lancet Neurol. 2008;7:993-1000. 

Gilden DH, Tyler KL. Bell’s palsy—is glucocorticoid treatment enough? N Engl J Med. 2007;357:1653. 

Hato N, Yamada H, Kohno H, et al. Valacyclovir and prednisolone treatment for Bell’s palsy: a multicenter, randomized, placebo-controlled study. Otol Neurotol. 2007;28:408. 

Hauser WA, Karnes WE, Annis J, Kurland LT. Incidence and prognosis of Bell’s palsy in the population of Rochester, Minnesota. Mayo Clin Proc. 1971;46:258. 

Karnes WE. Diseases of the seventh cranial nerve. In: Dyck PJ, Thomas PK, Lambert EH, et al, eds. Peripheral Neuropathy. 2nd ed. Philadelphia, PA: WB Saunders; 1984:1266-1299. 

Marx, John A, Robert S. Hockberger, Ron M. Walls, James Adams, and Peter Rosen. Rosen’s Emergency Medicine: Concepts and Clinical Practice. Philadelphia, PA: Mosby/Elsevier; 2010. 

Sullivan FM, Swan IR, Donnan PT, et al Early treatment with prednisolone or acyclovir in Bell’s palsy. N Engl J Med. 2007;357(16):1598-1607. 

Worster A, Keim SM, Sahsi R, Pancioli AM; Best Evidence in Emergency Medicine (BEEM) Group: 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. Epub 2009 Oct 21 (Review).

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