Efficacy of bedside optic nerve sheath diameter measurement in differentiating provoked seizure from unprovoked seizure in the emergency department

Abstract

BACKGROUND: Emergency departments (EDs) are typically the first medical contact for seizure patients, and early diagnosis and treatment is primarily the responsibility of emergency physicians. OBJECTIVES: Demonstrate the efficacy of bedside ocular ultrasonography for optic nerve sheath diameter (ONSD) measurement in differentiating provoked seizure from unprovoked seizure in the ED. DESIGN: Prospective observational study SETTINGS: Tertiary care hospital PATIENTS AND METHODS: Patients presenting to the ED with seizure were divided into two groups according to medical history, physical examination, laboratory results, cranial computed tomography findings and electroencephalography results. Patients with seizures that did not have a specific cause (unprovoked) were compared with patients who had seizures caused by underlying pathology (provoked). The measurement of the ONSD was taken at the bedside within 30 minutes of arrival. The study compared the ONSD values, age, sex, type of seizure, and Glasgow Coma Score between the two groups. MAIN OUTCOME MEASURE: Efficacy of ONSD to distinguish between provoked and unprovoked seizures. SAMPLE SIZE: 210 patients RESULTS: One hundred and fourteen (54.3%) patients were in the provoked seizure group and 96 (45.7%) were in the unprovoked seizure group. The ONSD measurements were significantly higher in the provoked seizure group compared with the unprovoked seizure group (median 6.1 mm vs. 5.2 mm, P<.001). The cut-off value of ONSD higher than 5.61 was significantly associated with the prediction of the provoked seizure (P<.001). The area under the curve value was 0.882 (95% CI: 0.830-0.922) with a sensitivity of 86.5 and specificity of 78.9%. CONCLUSIONS: Bedside ONSD measurement by means of ocular ultrasound is an effective method for differentiating provoked seizure from unprovoked seizure. LIMITATIONS: Statistical significance of age on ONSD and exclusion of pediatric patients. CONFLICT OF INTEREST: None.