sábado, 1 de agosto de 2009

Are antivirals effective in treating Bell’s palsy?

Evidence-Based Answer:
Available evidence is conflicting concerning the effectiveness of routine antiviral treatment for patients with Bell’s palsy. There may be benefit for patients with more severe cases (SOR C, extrapolated from heterogeneous randomized controlled trials [RCTs])Bell’s palsy is defined as acute idiopathic peripheral facial nerve paralysis.1 A viral etiology has been proposed and several reports have described an association with herpes simplex virus (HSV) infection.2 Rarely, varicella zoster infection can mimic Bell’s palsy by causing a Ramsay Hunt-like syndrome without the characteristic rash of shingles, a condition known as zoster sine herpete.1 For this reason, empiric use of antiviral agents, together with corticosteroids, is commonly initiated for patients with Bell’s palsy. A 2004 Cochrane review3 concluded that evidence was insufficient to adequately answer the question. The review identified 4 RCTs, however only 2 (with a total of 200 patients with Bell’s palsy) met inclusion criteria. One study did find improvement in 53 patients treated with acyclovir plus corticosteroid compared with steroid alone after 4 months (7.5% incomplete recovery with acyclovir plus corticosteroid vs 24% with corticosteroid alone: relative risk [RR]=0.32, 95% confidence interval [CI], 0.11-0.92; P=.04). The second study compared corticosteroid alone with acyclovir alone and favored the steroid group: after 3 months recovery was incomplete for 6.4% in the corticosteroid group versus 22% in the acyclovir group (RR=3.48; 95% CI, 1.05-11.60; P=.04). Analysis of adverse events was not possible due to lack of data. The Cochrane reviewers concluded that further well-designed RCTs with large sample sizes were needed. Since 2004, 2 large RCTs have addressed this question.One Scottish study4 included 551 patients with clinically diagnosed Bell’s palsy randomized into 1 of 4 treatment groups. Beginning within 72 hours of the onset of symptoms, patients were treated for 10 days with (a) 400 mg acyclovir 5 times daily plus placebo; (b) prednisolone 25 mg twice daily plus placebo; (c) acyclovir 400 mg 5 times daily and prednisolone 25 mg twice daily; or (d) 2 placebos. Analysis was performed primarily comparing prednisolone versus no prednisolone and acyclovir versus no acyclovir. Follow-up data were available for more than 90% of the participants. No significant increase was found in the number of patients who regained full facial function with acyclovir at 3 months (71.2% acyclovir vs 75.7% no acyclovir; odds ratio [OR] 0.86; 95% CI, 0.55-1.34) or at 9 months (85.4% acyclovir vs 90.8% no acyclovir; OR 0.61; 95% CI, 0.33-1.11). In addition, the acyclovir plus prednisolone group had actually fewer complete recoveries at 9 months (92.7%) than the prednisolone-only group (96.1%). The authors concluded that acyclovir treatment did not improve the probability of complete recovery from Bell’s palsy at 3 and 9 months.However, a nonblinded Japanese RCT,5 also published in 2007, did find improved recovery in the group of patients given antivirals. A total of 296 patients with relatively severe Bells’ palsy were recruited at 6 academic tertiary referral hospitals in Japan. All patients were given prednisolone. All patients underwent ELISA (enzyme-linked immunosorbent assay) and PCR (polymerase chain reaction) testing to exclude zoster infection; based on those test results, 23 patients (8%) were retrospectively considered to have zoster sine herpete (and not Bell’s palsy) and were excluded from analysis. Within 7 days of onset of symptoms, these patients were randomly assigned to 5 days of valacyclovir 500 mg twice daily plus prednisolone or placebo plus prednisolone. Follow-up were available for 75% of the participants.Six months after treatment, complete recovery was noted in 96.5% of the valacyclovir plus steroid group compared with 89.7% of the prednisolone-only group (P<.05). The differences were even more striking in the subgroup of patients with complete facial palsy (full recovery at 6 months: 90.1% with valacyclovir vs 75% without), whereas no difference was noted between groups for patients rated initially as having a moderate palsy (100% of these patients in both studies experienced complete recovery).
1. Gilden DH, Tyler KL. Bell’s palsy-is glucocorticoid treatment enough? N Engl J Med 2007; 357:1653-1655. [LOE 4]
2. Spruance SL. Bell palsy and herpes simplex virus. Ann Intern Med 1994; 120:1045-1046. [LOE 4]
3. Allen D, Dunn L. Aciclovir or valaciclovir for Bell’s palsy (idiopathic facial paralysis). Cochrane Database Syst Rev 2004; (3):CD001896. [LOE 1a]
4. Sullivan FM, Swan IR, Donnan PT, et al. Early treatment with prednisolone or acyclovir in Bell’s palsy. N Engl J Med 2007; 357:1598-1607. [LOE 1b]
5. 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; 28:408-413. [LOE 1b]HelpDesk Answer From EBP, David V. Power, MD, MPH Annie Arens, MS Primary Care Clerkship, University of Minnesota Medical School.

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