Woman With Facial Asymmetry of Abrupt Onset

A 57-year-old woman complains of burning and dryness in her left eye and altered sensation in her mouth when eating; these symptoms began the day before. A coworker who had noticed facial asymmetry recommended that she seek medical attention. The patient denies slurred speech, aphasia, weakness, numbness, and tingling in her extremities.

HISTORY

The patient has diabetes mellitus, which was diagnosed 10 years earlier. For several years, she took a sulfonylurea, but she found she could control her blood glucose level through diet and was able to stop drug therapy. She also has hypertension, for which she takes no medication. She last saw a physician about 2 years earlier. She neither smokes nor drinks.

About a week ago, while washing her dog, she was bitten by an insect on her right knee. The bite healed normally.

PHYSICAL EXAMINATION

Temperature is 37.2°C (99.1°F); heart rate, 108 beats per minute; respiration rate, 16 breaths per minute; blood pressure, 154/85 mm Hg; and arterial oxygen saturation, normal. The patient's left eye is open more than the right one, the left side of the forehead is smooth, and the left nasolabial fold is absent; her smile is asymmetrical. Aside from the facial nerve, other cranial nerves appear unaffected.

Strength is 5/5 in upper and lower extremities bilaterally, and results of cerebellar testing and of a Romberg test are normal. Results of the remainder of the physical examination are normal.

LABORATORY AND IMAGING RESULTS

White blood cell count is 6900/µL; hemoglobin level, 14.6 g/dL; and creatinine level, 0.4 mg/dL. A random blood glucose level is 310 mg/dL. A CT scan of the head shows no hemorrhage, gross space lesions, or infarction.

Which of the following statements about this patient is true?A. MRI will most likely demonstrate a contralateral hemispheric lesion.
B. Lyme disease is the most common infection associated with this syndrome.
C. Because of her coexisting diabetes, surgical decompression at day 28, rather than a course of corticosteroids, is the treatment of choice.
D. Her prognosis is good, and complete recovery is likely.

(Answer on next page.)

CORRECT ANSWER: D

This patient's presentation and initial findings are most consistent with Bell palsy, the most common cause of unilateral facial weakness of abrupt onset. Because this condition is idiopathic, other disorders (eg, a central lesion) must be ruled out before Bell palsy can be diagnosed.

CNS versus peripheral nerve involvement. Physical findings can help differentiate central lesions from peripheral nerve conditions (specifically, disorders affecting the facial nerve). A key finding is weakness in the upper face-a characteristic of peripheral nerve involvement but not of CNS involvement. Both peripheral nerve disorders and central lesions can affect the lower face. This patient's inability to close her left eye and the loss of her forehead creases on one side point to a disorder of the facial nerve rather than to a central lesion. Thus, choice A is incorrect.

Other causes of facial nerve deficit. These include mononeuritis from diabetes, HIV infection, Ramsay Hunt syndrome from herpes zoster, sarcoidosis, Sjögren syndrome, and Lyme disease. In fact, facial paralysis may be one of the more common manifestations of Lyme disease.¹ However, these conditions are far less common than Bell palsy.

The abrupt onset of the patient's symptoms helps rule out a number of causes of facial nerve deficit, such as parotid tumor or acoustic area tumor and inflammation; such entities have a more gradual onset. Moreover, these usually produce irritative as well as destructive signs (eg, dyskinesias) and other cranial nerve symptoms indicative of more widespread disease.²

Association with herpes simplex virus (HSV). The infectious agent most commonly associated with "idiopathic" Bell palsy is HSV type 1 (HSV-1). Virologic analysis of endoneurial fluid obtained during decompression surgery demonstrates HSV-l DNA in the vast majority of patients with Bell palsy; however, HSV-1 DNA is not found in patients with Ramsay Hunt syndrome. Most authorities now believe that HSV-l, reactivated from latency in the geniculate ganglion, is the cause of Bell palsy in the majority of patients.³ Thus, choice B is incorrect.

Diagnosis. In patients with acute (development of symptoms within 1 week) facial paralysis, if no cause is apparent and no other cranial nerve defects have occurred, testing (eg, MRI) is not required. If concomitant atypical features (eg, twitching or other irritative symptoms) are present or symptoms fail to resolve within 3 to 6 weeks, more aggressive evaluation is warranted.

Treatment. When the working diagnosis is Bell palsy, most experts suggest a short course (1 to 2 weeks) of corticosteroids, which was shown to be effective in several well-designed trials.⁴ This therapy was beneficial in trial participants who had diabetes; these results render somewhat moot the question of whether this patient's diabetes was the cause of her facial paralysis. In all the trials, prompt treatment was the most effective, and the majority of experts recommend that therapy be started within a week of symptom onset.

The rationale for using antivirals to treat presumed HSV infection is more conjectural, since few trials show that such treatment has an effect. However, some physicians add antivirals to the regimen.

The role of surgical decompression is also conjectural-and controversial. Observational studies comparing surgery with medical therapy have not confirmed any benefit for the former. Because nerve damage seems irreversible after 2 to 3 weeks, surgery-if it is considered at all-should not be performed 14 days or more after symptom onset.² Thus, choice C is incorrect based on the timing of intervention alone.

The prognosis for patients with Bell palsy is excellent (choice D). Older studies, in which many patients received no therapy, reported complete recovery in 71% of participants and achievement of near-normal function in 84%.⁵ Studies in which patients received corticosteroid therapy show a cure rate of greater than 90%.^2,4

Outcome of this case. The patient was given a 7-day course of prednisone, 60 mg, followed by a 7-day rapid tapering. A sulfonylurea was prescribed for her diabetes. Recovery had begun by day 5 and was nearly complete at day 21. Her blood glucose control was excellent and was not compromised by the prednisone.