The Incidence and Etiologies of Third Cranial Nerve Palsy in Koreans: A 10-year Nationwide Cohort Study.

Purpose This study aimed to determine the incidence, prevalence, and etiologies of third cranial nerve (CN3) palsy in Koreans. Methods Data were collected from the National Health Insurance Service-National Sample Cohort (NHIS-NSC) database of South Korea and analyzed. Incident CN3 palsy subjects in the cohort population were defined as cases occurring after the initial 4-year or longer washout period. The incidence and prevalence were analyzed by sex, age group, and year. The etiologies of CN3 palsy were evaluated using comorbidities. Results Of 1,108,253 subjects, 387 patients were newly diagnosed with CN3 palsy between 2006 and 2015. The incidence of CN3 palsy was 3.71 per 100,000 person-years (95% confidence interval, 3.35-4.09). The incidence of CN3 palsy increased with age and accelerated after the age of 60 years. The mean male-to-female incidence ratio was 1.16. The main cause was presumed to be vascular disease (52.7%), followed by idiopathic causes (25.8%), intracranial neoplasm (7.8%), unruptured cerebral aneurysm (5.4%), and trauma (5.2%). Conclusions The incidence of CN3 palsy in Koreans increased with age and peaked between 75 and 79 years. The main cause of CN3 palsy was vascular disease.