Increased risk of Bell palsy in patients with migraine: a nationwide cohort study

Abstract

Objective: To evaluate the association between migraine and Bell palsy and to examine the effects of age, sex, migraine subtype, and comorbid risk factors for Bell palsy.

Methods: This nationwide cohort study was conducted using data from the Taiwan National Health Insurance Research Database. Subjects aged 18 years or older with neurologist-diagnosed migraine from 2005 to 2009 were included. A nonheadache age- and propensity score-matched control cohort was selected for comparison. All subjects were followed until the end of 2010, death, or the occurrence of a Bell palsy event. Cox proportional hazards regression was used to calculate the adjusted hazard ratios and 95% confidence intervals to compare the risk of Bell palsy between groups.

Results: Both cohorts (n = 136,704 each) were followed for a mean of 3.2 years. During the follow-up period, 671 patients (424,372 person-years) in the migraine cohort and 365 matched control subjects (438,677 person-years) were newly diagnosed with Bell palsy (incidence rates, 158.1 and 83.2/100,000 person-years, respectively). The adjusted hazard ratio for Bell palsy was 1.91 (95% confidence interval, 1.68-2.17; p < 0.001). The association between migraine and Bell palsy remained significant in sensitivity analyses, and tests of interaction failed to reach significance in all subgroup analyses.

Conclusion: Migraine is a previously unidentified risk factor for Bell palsy. The association between these 2 conditions suggests a linked disease mechanism, which is worthy of further exploration.