Watershed infarctions are more prone than other cortical infarcts to cause early-onset seizures

Background: Early-onset seizures(ESs) have been reported in 2% to 6% of strokes. Most previous studies have been retrospective and did not systematically perform cerebral magnetic resonance imaging (MRI). Objective: To determine the prevalence and determinants of ESs in a prospective cohort. Design: Prospective cohort study. Setting: Stroke unit in an academic hospital. Patients: Six hundred sixty-one consecutive individuals admitted to our stroke unit during an 18-month period for suspected stroke. Main Outcome Measures: Initial investigations systematically included cerebral MRI. Among patients with MRI-confirmed cerebral infarction, individuals with ES, defined as occurring within 14 days of stroke, were identified. Results: Three hundred twenty-eight patients had MRI-confirmed cerebral infarcts and 178 had cortical involvement. The ESs, all initially partial seizures, occurred in 14 patients (4.3%) and at stroke onset in 5 patients. The ESs occurred exclusively in patients with cortical involvement (P<.001). With infarcts involving the cerebral cortex, there was a higher risk of ESs in watershed infarctions than in territorial strokes (6 of 26 [23.1%] vs 8 of 152 [5.3%], P=.007). Logistic regression analysis showed an almost 4-fold increased risk of ES in patients with watershed infarctions compared with other cortical infarcts (odds ratio, 4.7; 95% confidence interval, 1.5- 15.4; P=.01). Age, sex, diabetes mellitus, hypertension, smoking, National Institutes of Health Stroke Scale score, and cardioembolic origin were not significant risk factors for ES. Conclusions: The cortical hemispheric location of ischemic strokes is associated with a higher risk of ES. Among these patients, the watershed mechanism is a strong and independent determinant of stroke-related ES. ©2010 American Medical Association. All rights reserved.