Incidence and risk factors for Bell's palsy in Laredo, Texas: 1974-1982.

Incidence rates of Bell's palsy in the predominantly Mexican-American population of Laredo, Texas, USA, are higher than those reported elsewhere, reaching 23.5 per 100,000 among males and 32.7 per 100,000 among females. During childbearing years (15-44) the risk of Bell's palsy was greater for women than for men (incidence density ratio 2.0; 95% confidence interval 1.3-3.1). No evidence for seasonality or epidemicity was obtained. Using prevalence estimates from community surveys in south Texas or the Hispanic Health and Nutrition Survey, standardized prevalence ratios (SPR) calculated for hypertension revealed a 10 or 20% increased risk for women and a 50 or 60% increased risk for men. SPRs calculated for diabetes among men with Bell's palsy were twice that expected, while risks of 60% or 90% were noted for women. The increased incidence of Bell's palsy observed in Laredo appears to be due to the high prevalence of diabetes in Mexican-Americans and, to a lesser extent, uncontrolled hypertension.