Wiler, Jennifer L. MD, MBA
A 43-year-old woman presents with a one-day history of left-sided facial weakness. She noticed that the left side of her face felt numb two days before, and that noises bothered her. She denied a history of headache, trauma, fever, recent camping, exposure to ticks, being pregnant, facial swelling, pain, or any previous medical problems. She is very concerned that she has had a stroke because her best friend had a devastating stroke the year before. This is what you see when you ask her to smile, show her teeth, and wrinkle her forehead.
What is the likely diagnosis and treatment of this condition?
Diagnosis: Bell's Palsy
Bell's palsy is used to describe cranial nerve VII weakness or paralysis, and has affected many famous faces including George Clooney, Pierce Brosnan, and Ralph Nader. Although the term was once reserved for only idiopathic or cryptogenic etiologies, numerous conditions predispose to the Bell's palsy, with a known etiology in 50 percent of cases. Bell's palsy was first described by the Scottish surgeon Charles Bell in the 1800s, and is the most common cause of acute mononeuropathy facial paralysis, affecting approximately 40,000 patients per year. Because of the sudden onset of symptoms (usually over hours), patients with the condition are often frightened that they have had a stroke or have a brain tumor.
The exact etiology is unknown, but infectious, vascular (hypertension), immunologic, metabolic (diabetes), emotional, environmental, and genetic factors (reported in about 4% of cases) may play a role. It is thought that Bell's palsy is the result of nerve inflammation, swelling, and subsequent impingement as the nerve traverses the narrow Fallopian canal within the temporal bone, resulting in local ischemia and demyelination of the facial nerve from compressive forces. Conditions known to cause a peripheral cranial neuropathy and facial paralysis include nerve damage from trauma, multiple sclerosis, otitis media, Ramsay Hunt syndrome (zoster), osteomyelitis of the skull base, tumor, and compressive aneurysm, but are not typically classified as Bell's palsy.
Although controversial, reactivation of a latent herpes simplex infection is thought to be the underlying etiology in most cases (APMIS 1997;105: 815), with varicella zoster virus reactivation being the second most common etiology. Other reported infectious etiologies of Bell's palsy include cytomegalovirus, rubella, coxsackie, adenovirus, Mycoplasma pneumoniae, and hepatitis A, B, and C.
Bell's palsy afflicts approximately one in 65 people over a lifetime, with an increased incidence of nearly 30 percent in diabetics. It is uncommon in children under 15 and adults over 70. There is no gender predilection, but increased risk exists for pregnant patients (especially in the third trimester or immediately postpartum), diabetics, or those with an upper respiratory infection.
Patients typically present with acute onset of unilateral facial weakness or paralysis with symptoms typically reaching a peak within 48 hours. Bilateral involvement is rare. Waxing and waning or slowly progressive symptoms suggest tumor. Patients with unilateral peripheral CN VII neuropathy are unable to close their eye, have dryness of the eye (60%) and mouth, sagging eyebrow, forehead flattening, nasolabial fold flattening, sagging mouth corner, hyperacusis, and loss of taste on the anterior two-thirds of the tongue (30%). Presentations sparing the forehead suggest a central lesion because of bilateral motor innervation. Patients also may complain of headache, dizziness, pain in front or behind the ear (50% of patients), and difficulty eating or drinking.
Asking the patient to close the affected eye, smile, show the teeth, elevate the brow, and puff out the cheeks will magnify the deficit. When the patient attempts to close the affected eye, the eye rolls superior and medially. A complete neurologic examination with particular attention to the cranial nerves should be performed to rule out subtle findings. Examination of the face and auditory canal also should be performed to rule out herpetic lesions (suggestive of Ramsay Hunt), otitis, or masses that explain the underlying etiology of the peripheral nerve impairment.
Bell's palsy is a clinical diagnosis based on exclusion; no laboratory studies can confirm it. Computed tomography or magnetic resonance imaging should be considered for patients with slowly progressive or atypical symptoms, if facial spasms or twitches precede the onset of weakness (concerning for tumor; N Engl J Med 2004;351: 1323), or if life-threatening or surgical etiologies of the CN VII nerve palsy (tumor or abscess) are entertained. Electromyography studies are not performed in the acute ED setting, but can help with prognostic determinations in patients with complete CN VII paralysis.
The emergency physician must rule out underlying etiology for the facial palsy, and initiate appropriate treatment if one is identified, protect the eye, treat pain, and arrange appropriate outpatient follow-up with a neurologist, ophthalmologist, or otolaryngologist. Patients with Bell's palsy lose the ability to blink and naturally lubricate the eye with tears, and are at increased risk of dry eyes and corneal irritation/abrasion. It's recommended that patients wear a patch, and lubricate the eye with artificial tears every hour during the day and with ointment at night to prevent conditions leading to permanent visual impairment.
No standard treatment exists for Bell's Palsy (www.ninds.nih.gov), and a 2004 Cochrane review concluded that trials should evaluate antiviral drugs or corticosteroids. Since then, a multicenter randomized trial of 551 patients given oral prednisolone, oral acyclovir, both, or placebo early (within 72 hours) for 10 days found early treatment with prednisolone significantly increased recovery. No additional benefit was seen with acyclovir alone or when given in combination with prednisolone. (N Engl J Med 2007;357: 1598.) Treatment with a limited dose of prednisone is currently recommended within 72 hours of onset for all patients. Antiviral treatment should be considered only for patients where a herpetic etiology is presumed.
Electrical nerve stimulation, physical therapy, and acupuncture have limited published outcomes data, and a 2007 Cochrane review found the quality of acupuncture trials inconclusive. A 2008 review found no evidence of significant harm or benefit from physical therapy, and decompression surgery of the nerve is controversial and rarely performed.
This condition reaches maximal intensity within 48 hours and improves within two weeks, with nearly 80 percent reporting complete resolution within three to six months. Some cases may not resolve, may become bilateral, or may recur in approximately eight to 10 percent. Patients with incomplete lesions have a higher rate of complete recovery than those with complete unilateral paralysis. Patients with delayed onset of prednisone therapy, severe weakness, hearing impairment, and a history of recurrence tend to have poorer outcomes. (J Med Assoc Thai 2008;91:1182.)
This patient was given a short course of steroids and artificial eye lubrication, and was discharged with neurology follow-up.
© 2009 Lippincott Williams & Wilkins, Inc.