High Incidence of Bell's Palsy After Mastoidectomy: A Longitudinal Follow-up Study.

Objective: The objective of this study was to compare the prevalence of Bell's palsy in participants who underwent mastoidectomy (to treat chronic otitis media) and nonmastoidectomy participants (control).

Methods: Using the national cohort study from the Korean Health Insurance Review and Assessment Service, mastoidectomy patients (2,045) and control participants (8,180) were matched 1:4 for age, sex, income, and region of residence. The prevalence of Bell's palsy in both the groups was measured from 0 to 10 years postoperation.

Results: In a sample of 1,025,340 Korean individuals, 7,070 were diagnosed or treated with Bell's palsy between 2002 and 2013; the annual incidence of Bell's palsy was 0.057%. The overall prevalence of Bell's palsy was three times higher in the mastoidectomy group (1.27%) than control group (0.49%) (p < 0.001). The prevalence of Bell's palsy was different between the two groups in postoperative 0 year: 0.78% for the mastoidectomy group versus 0.01% for the control group (p < 0.001).

Conclusion: Although we could not verify the laterality, the prevalence of Bell's palsy was increased in chronic otitis media patients treated with mastoidectomy patients compared with controls, especially within a year after surgery.