Increased Risk of Stroke in Patients with Isolated Third, Fourth, or Sixth Cranial Nerve Palsies: A Nationwide Cohort Study.

BACKGROUND AND PURPOSE The aim of this nationwide cohort study was to evaluate whether the occurrence of isolated 3rd, 4th or 6th cranial nerve (CN) palsies is associated with a higher risk of ischemic stroke. METHODS This study utilized data from Taiwan Longitudinal Health Insurance Database during 1995-2012. Subjects aged 20 years or older who had isolated CN 3/4/6 palsies diagnosed by a neurologist or ophthalmologist between January 2000 and December 2011 were included. A set of propensity score matched, randomly sampled patients who had never been diagnosed with CN 3/4/6 palsies were extracted to constitute the control group (cases and controls = 1:4). All subjects were followed until death, loss due to follow-up or completion of the study. Cox proportional hazard regression model stratified by matched pairs was used to estimate the hazards ratio (HR) of ischemic stroke. RESULTS A total of 657 patients with isolated CN 3/4/6 palsies (61.1% male, mean age 54.8 years) were identified. Compared with control group, the patients with isolated CN 3/4/6 palsies exhibited an increased risk of ischemic stroke (CN3: adjusted HR 3.69 (95% CI 2.20-6.19); CN4: 2.71 (95% CI 1.11-6.64); CN6: 2.15 (95% CI 1.31-3.52)). The association between CN 3/4/6 palsies and ischemic stroke was detected in both separate subgroup and sensitivity analyses. CONCLUSIONS The patients with CN 3/4/6 palsies exhibited an increased risk of developing ischemic stroke. Therefore, isolated ocular motor nerves palsies appear to represent an unrecognized risk factor for ischemic stroke, and these require further confirmation and exploration.