Stroke risk among adult patients with third, fourth or sixth cranial nerve palsy: a Nationwide Cohort Study.

PURPOSE: This study sought to determine whether isolated third, fourth and sixth cranial nerve palsies (NPs) are associated with increased short- and long-term risk of a subsequent stroke.

METHODS: This was a nationwide retrospective propensity score-matched cohort study. A cohort of patients with NP (n = 466) and a randomly selected, propensity-matched control cohort (n = 2281) were extracted from the Korean national insurance claim database. Subjects were tracked for 5 years total, subdivided into periods of 0-1 years, 1-3 years and 3-5 years. We assessed the risk of stroke using hazard ratios (HRs) and confidence intervals (CIs) after adjustments using Cox regression at different time intervals.

RESULTS: The median follow-up was 3.1 years. Stroke developed in 18.9% of the NP cohort and 7.5% of the control cohort. Stroke risk after NP was highest in the first year [14.7 per 100 person-year at 0-1 years (HR = 6.6), 3.1 per 100 person-year at 1-3 years (HR = 1.6) and 4.3 per 100 person-year at 3-5 years (HR = 2.8)]. Each type of NP was also associated with stroke risk: within 0-1 years, stroke risk was increased in third (HR = 7.6), fourth (HR = 6.0) and sixth (HR = 5. 84) NPs. In the 3- to 5-year period, risk was increased in sixth (HR = 4.7) and fourth (HR = 3.3) NPs, but not third (HR = 0.6) NPs.

CONCLUSION: Patients in the NP cohort were more likely to have a stroke than those in the matched control cohort; the increased risk was both time- and cranial nerve-dependent.