Prognostic factors for the outcome of Bells' palsy: A cohort register-based study.

OBJECTIVES

There is a lack of data on patients' and diagnostic factors for prognostication of complete recovery in patients with Bell's palsy.

DESIGN AND SETTING

Cohort register-based study of 368 patients with Bell's palsy and uniform diagnostics and standardised treatment in a university hospital from 2007 to 2017 (49% female, median age: 51 years).

MAIN OUTCOME MEASURES

Clinical data, facial grading, electrodiagnostics, motor function tests, non-motor function tests and onset of prednisolone therapy were assessed for their impact on the probability of complete recovery using univariable and multivariable statistics.

RESULTS

Median onset of treatment was 1.5 days. 46% of patients had a House-Brackmann scale at baseline of ≥ III. The median recovery time was 2.6 months (95% confidence interval [CI] = 2.1-3.0). 54.9% achieved a complete recovery. If prednisolone therapy started later than 96 hours after onset, the recovery rate decreased significantly. Beyond less severe palsy, no abnormal electroneurography side difference, no pathological spontaneous activity in electromyography and normal stapedius reflex testing were the most powerful tool for prognostication of recovery after Bell's palsy.

CONCLUSION

Beyond severity of the palsy, facial electrodiagnostics and stapedius reflex testing are the most powerful tool for prognostication of recovery time after Bell's palsy. Prednisolone therapy should have started at best within a time window of 96 hours after onset to reach the highest probability of complete recovery.