Definitions of the levels of the recommendations (A, B, C, U) and classification of the evidence (Class I-IV) are provided at the end of the "Major Recommendations" field.
For patients with new-onset Bell palsy, oral steroids should be offered to increase the probability of recovery of facial nerve function (Level A).
For patients with new-onset Bell palsy, antivirals (in addition to steroids) might be offered to increase the probability of recovery of facial function (Level C). Patients offered antivirals should be counseled that a benefit from antivirals has not been established, and, if there is a benefit, it is likely that it is modest at best (risk difference [RD] <7%).
Putting the Evidence into A Clinical Context
Although there is strong evidence that steroid use increases the probability of good facial functional recovery in patients with Bell palsy, it does not necessarily follow that all patients with Bell palsy need to take steroids. For example, it would be reasonable for a clinician to opt not to use steroids in a patient with brittle diabetes mellitus. Other comorbidities potentially requiring further consideration include morbid obesity, osteopenia, and a prior history of steroid intolerance.
The authors found limited evidence of the efficacy of steroids and antivirals in important Bell palsy subgroups, including those with a lower probability of recovery because of severe palsy at presentation and those with possible zoster sine herpete. Such studies are particularly important relative to the efficacy of the addition of antivirals to steroids given the lack of evidence for moderate efficacy in the "typical" patient with Bell palsy.
Authors of one Class I study performed a preplanned subgroup analysis on patients with severe palsy at presentation defined by a Sunnybrook Scale score of 0 to 25. This analysis showed no significant difference in 12-month recovery rates between patients treated with prednisolone alone as compared with patients treated with prednisolone plus valacyclovir (RD 0.2% favoring valacyclovir 95% confidence intervals [CI], -18% to 17.6%). However, the analysis lacked the statistical precision to exclude an important beneficial effect (or harm) from the addition of valacyclovir. A Class IV study observed a significant improvement in recovery (RD 26.6%) between patients with severe Bell palsy treated with prednisone alone and patients with severe Bell palsy treated with prednisone plus famciclovir (House-Brackmann Scale score of 5 or 6). This study had a high risk of bias because of pseudorandomized treatment allocation and unmasked outcome assessment.
Relative to zoster sine herpete, a Class IV study observed no significant difference in recovery after treatment with prednisolone alone as compared with treatment with prednisolone plus valacyclovir in a subgroup of 28 patients with evidence of zoster reactivation (hazard ratio for recovery 1.6 favoring prednisolone plus valacyclovir, 95% CI 0.4 to 6.1). The small sample size and high risk of bias make this observation inconclusive.
These studies in aggregate do not provide strong evidence to identify subgroups of patients that might benefit more or less from treatment.
Because the studies included only patients presenting early after palsy onset, it is difficult to determine the effect of steroid or antiviral treatment in patients presenting later in the course of their illness (e.g., 1 week after the onset of facial weakness). Likewise, although it seems reasonable to assume that an equivalent dose of alternative steroids would also be effective, decisions regarding alternative steroid dosing regimens necessarily require clinician judgment.
Classification of Evidence
Class I: Prospective, randomized, controlled clinical trial with masked outcome assessment, in a representative population. The following are required:
- Concealed allocation
- Primary outcome(s) clearly defined
- Exclusion/inclusion criteria clearly defined
- Adequate accounting for drop-outs and cross-overs with numbers sufficiently low to have minimal potential for bias
- Relevant baseline characteristics are presented and substantially equivalent among treatment groups or there is appropriate statistical adjustment for differences.
Class II: Prospective matched group cohort study in a representative population with masked outcome assessment that meets a-e above OR a randomized controlled trial (RCT) in a representative population that lacks one criteria a-d.
Class III: All other controlled trials (including well-defined natural history controls or patients serving as own controls) in a representative population, where outcome is independently assessed, or independently derived by objective outcome measurement*.
Class IV: Evidence from uncontrolled studies, case series, case reports, or expert opinion.
*Objective outcome measurement: An outcome measure that is unlikely to be affected by an observer's (patient, treating physician, investigator) expectation or bias (e.g., blood tests, administrative outcome data).
Strength of Recommendations
A = Established as effective, ineffective or harmful (or established as useful/predictive or not useful/predictive) for the given condition in the specified population. (Level A rating requires at least two consistent Class I studies.)**
B = Probably effective, ineffective or harmful (or probably useful/predictive or not useful/predictive) for the given condition in the specified population. (Level B rating requires at least one Class I study or two consistent Class II studies.)
C = Possibly effective, ineffective or harmful (or possibly useful/predictive or not useful/predictive) for the given condition in the specified population. (Level C rating requires at least one Class II study or two consistent Class III studies.)
U = Data inadequate or conflicting; given current knowledge, treatment (test, predictor) is unproven.
**In exceptional cases, one convincing Class I study may suffice for an "A" recommendation if 1) all criteria are met, 2) the magnitude of effect is large (relative rate improved outcome > 5 and the lower limit of the confidence interval is > 2).