Clinical Question

Are antivirals effective therapy for Bell palsy?

Evidence-Based Answer

The combination of antiviral agents and corticosteroids is more effective than corticosteroids alone for the complete recovery of patients with Bell palsy (number needed to treat [NNT] = 15) and for the resolution of motor synkinesis and excessive tear production (NNT = 12). (Strength of Recommendation [SOR]: B, based on inconsistent or limited-quality patient-oriented evidence.) Antivirals should not be used alone to treat Bell palsy. (SOR: A, based on consistent, good-quality patient-oriented evidence.)

Practice Pointers

Untreated idiopathic facial paralysis, or Bell palsy, leaves up to 30% of patients with some level of permanent facial asymmetry or pain.¹ Previous meta-analyses have demonstrated the effectiveness of corticosteroids at reducing the rate of long-term disability.² Some evidence suggests that recurrent viral infections, including herpes simplex virus and varicella zoster virus, are common causes of Bell palsy. This review evaluated the effectiveness of antiviral agents alone or in combination with corticosteroids for the treatment of Bell palsy. An earlier version of this review, which included two low-quality studies judged to be at high risk of bias, concluded that the combination of antivirals and corticosteroids was no more effective than corticosteroids alone for the treatment of Bell palsy.³

This Cochrane review included 10 trials with a total of 2,280 participants. The authors used meta-analysis to compare several treatment regimens and a variety of outcomes. Complete recovery rates of facial nerve function in patients with Bell palsy were improved by treatment with corticosteroids plus antivirals vs. corticosteroids alone at six months (relative risk [RR] = 0.61; 95% confidence interval [CI], 0.39 to 0.97; NNT = 15 [95% CI, 10 to 200]; n = 1,315). A subgroup analysis of patients with severe Bell palsy (i.e., House-Brackmann index of 5 or 6 out of 6) found that more patients achieved complete recovery when the combination of antivirals and corticosteroids was used vs. corticosteroids alone (RR = 0.64; 95% CI, 0.41 to 0.99; n = 478).

The combination of corticosteroids and antivirals also improved long-term motor synkinesis and excessive tear production (so-called “crocodile tears”) over corticosteroids alone (RR = 0.56; 95% CI, 0.36 to 0.87; NNT = 12 [95% CI, 8 to 40]; n = 469]). Treatment with antivirals alone was associated with higher rates of residual symptoms vs. treatment with corticosteroids alone (RR = 1.52; 95% CI, 1.08 to 2.12; n = 472). The rate of adverse effects was similar among all of the treatments compared.

The results of this review differ slightly from another meta-analysis that found that the routine addition of antivirals to corticosteroid therapy did not improve at least partial recovery.⁴ In that meta-analysis, the authors found that adding antivirals to corticosteroid therapy benefits only patients with severe Bell palsy. In subgroup analyses, the type of antiviral administered did not change outcomes. However, this meta-analysis included only one-half as many patients as the current Cochrane review, which may have led to a lack of statistical power.

Guidelines on Bell palsy from the American Academy of Otolaryngology–Head and Neck Surgery Foundation currently recommend prescribing oral corticosteroids within 72 hours of symptom onset (grade A) and recommend against the use of antiviral monotherapy (grade A).⁵ These guidelines state that physicians may opt to prescribe antiviral therapy in addition to corticosteroid therapy (option, grade B) because studies do not exclude a small effect. The American Academy of Neurology provides similar recommendations, stating that physicians should routinely prescribe corticosteroids to patients with Bell palsy and that they may consider offering antivirals in addition, although there may be no benefit (level C).⁶