In Summary, for those who received corticosteroids:

Benefits in NNT

    11% avoided an incomplete recovery (residual facial weakness) of Bell’s palsy at 6 months
    10 avoided an incomplete recovery (residual facial weakness) of Bell’s palsy at 6 months

Harms in NNT

    No one was harmed
    No one was harmed

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Source: Madhok VB, Gagyor I, Daly F, Somasundara D, Sullivan M, Gammie F, Sullivan F. Corticosteroids for Bell’s Palsy (Idiopathic Facial Paralysis). Cochrane Database of Systematic Reviews 2016, Issue 7. Art. No.: CD001942.

Efficacy Endpoints: Primary: Prevention of incomplete recovery of facial motor function at 6 months after randomization. Secondary: Cosmetically disabling sequelae (severe paralysis), motor synkinesis, and autonomic dysfunction (crocodile tears)

Harm Endpoints: Adverse effects attributable to the use of corticosteroids Who was studied: 895 participants with Bell’s palsy from 7 separate trials

Narrative: Bell’s palsy is an acute, usually unilateral paralysis or weakness of the facial muscles due to facial nerve dysfunction generally of idiopathic origin, although viral infection, autoimmune disorder, and heredity have all been proposed as underlying causes. The incidence is believed to be between 23 and 37 per 100,000 per year. It affects men and women equally but disproportionately affects pregnant women and people with diabetes or a transient viral infection such as influenza or common cold. The prognosis is generally favorable, with 85% of people having some recovery within three weeks of onset. However, approximately 16% of patients may have permanently altered function of the facial nerve, including muscle spasms, aberrant innervation leading to motor synkinesis and/or autonomic dysfunction leading to crocodile tears (lacrimation while eating).

Because of the underlying theory that Bell’s Palsy is an inflammatory disorder, corticosteroids have historically been used as treatment. This 2016 Cochrane review provides an update on a previous review from 2010 summarizing the data on potential benefits of corticosteroid treatment for Bell’s palsy.1 The update encompassed new methodologies and evidence; in addition, it excluded previously included studies involving participants treated with antiviral therapy.

In all, this review encompassed 895 participants from seven trials, occurring from 1954 to 2008. All trials used some form of randomization, and five trials were double-blinded. Participants were of any age with clinically diagnosed Bell’s palsy considered eligible by study authors, irrespective of associated medical conditions.

As with prior reviews, a benefit was noted for participants taking corticosteroids for Bell’s palsy with a primary outcome of reduced rates of incomplete recovery. Specifically, the number of people with incomplete recovery at six months after randomization was lower in the corticosteroid group compared to the control group with a relative risk (RR) of 0.63 (95% CI, 0.5 to 0.8). The number of people who need to be treated with steroids to prevent one person from having an incomplete recovery was 10 (95% CI 6 to 20). Incomplete recovery was defined as persistent or residual facial weakness after six months after randomization as determined by any grading system or scale.

Two trials provided data for the secondary outcome of cosmetically disabling sequelae (described as severe paralysis), and no statistically significant benefit to corticosteroid use was found for this secondary outcome.

Three trials (485 patients) provided data for another secondary outcome of motor synkinesis (a wide spectrum of unwanted facial movements) and a statistically significant reduction in the number of people with motor synkinesis in the corticosteroid groups was found (RR 0.64, 95% CI, 0.45 to 0.91).

Regarding adverse effects attributed to the use of corticosteroids, three studies recorded an absence of adverse effects; one trial reported that three participants had had temporary sleep disturbances; two trials detailed an account of 93, non-serious adverse effects that were found in both corticosteroid and placebo arms. Three deaths were reported, all in the placebo group, and none of which were believed to be related to Bell’s Palsy.

The authors of the Cochrane review conclude that the available evidence shows that corticosteroids significantly reduce the frequency of incomplete recovery from Bell’s Palsy. Furthermore, they find that there is an adequate body of evidence to support the consideration of corticosteroids as a standard treatment in Bell’s Palsy with future trials comparing interventions against this treatment.

Caveats: There was significant variability in dosage and the type of corticosteroids among the included trials. For example, one study’s gave participants 30 mg of prednisone twice daily for five days followed by taper, whereas another gave 410 mg of prednisone once daily followed by taper. One study used cortisone acetate, while another used weight-based dosing of methylprednisolone.

There was also some variability on the follow up time for primary outcome. Most studies followed up regularly including at 6 months, whereas others evaluated at 9 or 12 months.

The initiation of therapy and randomization of participants was also inconsistent. Most studies reported beginning the treatment within two days, but one study began treatment within 10 days.

As the included trials did not exclude based on age or sex, and no subgroup analyses was performed, no conclusions can be drawn on the use of steroids in pediatrics, geriatrics, men, women, or other important demographic characteristics.

The authors of the Cochrane systematic review report “marginally significant” heterogeneity between trials, which they attributed to differences between large studies and smaller underpowered studies. However, the authors report that, when combined, the seven studies provide high quality evidence for the primary outcome of incomplete recovery at six months. Data for the secondary outcomes of motor synkinesis drawn from three studies was determined to be moderate-quality evidence, as was evidence for lack of adverse effects. Overall, the risk for most of the studies was found to be low risk.

Last, it should be understood that facial paralysis encompasses several infectious and non-infectious causes. Care should be taken by the treating clinician to distinguish various causes of facial palsy as no benefit has been shown to giving corticosteroids with lyme disease-associated facial nerve palsy and one study shows the association of worsening morbidity2.

Percent of incomplete recovery after 6 months:

Corticosteroid group: 79/452 (17%)
(17%, 95% CI, 21-24%)

Placebo group: 125/447 (28%)
(28%, 95% CI, 13-16%)

Risk Ratio: 0.63 (95% CI, 0.5-0.8)

NNT: 10 (95% CI, 6-20)

Harm Outcome:

There was no evidence of life threatening side effects and there was no significant difference in adverse effect rates between subjects receiving corticosteroids and those receiving placebo.

Author: Michael Griesinger, MD and Walter Valesky, MD

Published/Updated: February 8, 2018

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    • Green: Benefits outweigh risks.
    • Yellow: Unclear risk/benefit profile.
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    • Black: Obvious harms, no clear benefits.
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