Updated evidence strengthens the recommendation to use steroids, such as prednisone, to treat Bell's palsy but suggests that adding an antiviral agent may not be beneficial.
The new guideline for treating Bell's palsy is based on evidence emerging since 2001 recommendations published by the Quality and Standards Subcommittee of the American Academy of Neurology (AAN).
"The level of evidence supporting the use of steroids has increased," coauthor Gary S. Gronseth, MD, Department of Neurology, University of Kansas Medical Center, Kansas City, told Medscape Medical News. "The last time, we concluded that this was probably effective, and now we conclude it's highly likely to be effective. It's a level A recommendation whereas before, it was level B recommendation."
Dr. Gronseth stressed that even though steroids for Bell's palsy now have a level A recommendation, it doesn't follow that all of these patients need to take steroids.
A second major change is that whereas the earlier guideline had concluded that antiviral agents were possibly effective, the newer evidence is negative. "It showed that this is not helpful, although these studies didn't have sufficient statistical power to exclude a possible modest benefit," said Dr. Gronseth.
The new guideline is published online November 7 in Neurology.
Bell's palsy is common, with an annual incidence of 20 per 100,000. Of these cases, 70% to 85% will resolve without treatment, the authors write.
The condition is caused by inflammation within a cranial nerve in the temple bone, presumably related to mechanical compression. The cause of this inflammation is unknown, although 1 theory is that it stems from reactivation of herpes simplex virus, said Dr. Gronseth.
Along with his coauthor, Remia Paduga, MD, Dr. Gronseth searched MEDLINE and the Cochrane Database of Systematic Reviews and Controlled Clinical Trials for relevant articles that included functional outcomes after 3 or more months of follow-up in at least 20 patients with new-onset Bell's palsy and that compared patients treated with steroids or antiviral agents with those not treated with these agents.
They defined facial function as "good" or "complete" by using the same criteria as in the 2001 practice guideline. In studies using the House and Brackmann facial function scoring system, they considered an outcome of grade I or II as good recovery. They rated studies for their risk of bias using the AAN 4-tiered classification of evidence scheme for therapeutic studies, and they re-rated studies from the original guideline by using the updated classification of evidence.
The new analysis included 3 studies, published in 2002 (class II), 2007 (class I), and 2008 (class I), that compared outcomes in patients with Bell's palsy treated with a steroid with outcomes in those not treated with a steroid.
Both class I studies randomly assigned patients to prednisolone or placebo, and both demonstrated a significant increase in the probability of complete recovery in those assigned to the steroid; the risk difference favoring steroids was 12.8% (Sullivan, 2007) and 15% (Egstrom, 2008) respectively.
Adverse events linked to the steroid, the most commonly reported being insomnia and dyspepsia, tended to be minor and temporary.
"I don't think we need to study steroids anymore," commented Dr. Gronseth. "It's pretty well known now that they work."
However, future research should be directed at finding the optimal dose and timing of steroids, and determining the effect of steroids in children and other specific populations, said the authors.
The reviewers found 8 studies that compared outcomes in patients treated with an antiviral agent. Five of these studies were rated class IV because of nonindependent, nonmasked, and nonobjective outcome assessments.
Of the rest, 2 studies, published in 2007 and 2008, were class I. Both compared outcomes in patients randomly assigned to an antiviral agent or placebo and compared outcomes in patients taking an antiviral agent plus a steroid with patients receiving a steroid alone. Acyclovir was used in all but 1 study; that study used valacyclovir.
None of the class I studies demonstrated a significant improvement with an antiviral agent compared with placebo (risk difference, 4% favoring placebo). Adding an antiviral agent to a steroid compared with a steroid alone offered no significant benefit.
However, the evidence here was somewhat nuanced, as the 95% confidence intervals of the class I studies indicated that a modest benefit of up to 7% couldn't be excluded "The evidence shows that there's no significant association between taking antivirals and having a better outcome, but the evidence lacks statistical precision," said Dr. Gronseth. "Everyone interprets that as negative, but that's inappropriate."
Adding an antiviral agent to a steroid to increase the probability of recovery of facial function received a level C recommendation.
No study showed a significant increase in any adverse event for patients taking an antiviral agent.
There may, however, be some patients with Bell's palsy for whom an antiviral agent might be an option, he said. These include, for example, patients with "very brittle" diabetes who may not tolerate a steroid, those who developed steroid psychosis in the past, and those who are morbidly obese for whom water retention may be an issue, said Dr. Gronseth.
Dr. Gronseth serves as an editorial advisory board member of Neurology Now, served on a speakers' bureau for Boehringer Ingelheim, and receives honoraria from Boehringer Ingelheim and the AAN. Dr. Paduga has disclosed no relevant financial relationships.
Neurology. 2012;79:1-5. Published online November 7, 2012. Abstract
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Cite this: New AAN Guideline on Bell's Palsy - Medscape - Nov 07, 2012.