Diagnostic Yield of Neuroimaging in Patients With Nonindex Seizures in the Emergency Department

Objectives: The diagnostic yield of neuroimaging in patients with nonindex seizures, defined as those with established epilepsy presenting to the emergency department with a recurrent seizure, remains uncertain. Although head computed tomography (CT) is frequently performed, its impact on clinical decision-making is often limited. This study aimed to assess the frequency of neuroimaging use, its diagnostic yield, and the clinical factors associated with acute findings leading to management changes. Methods: We conducted a retrospective observational study of adult patients with epilepsy presenting with nonindex seizures to a tertiary public hospital in Bogotá, Colombia, between February 2023 and February 2024. Sociodemographic, clinical, and neuroimaging data were extracted from electronic medical records. Descriptive and bivariate analyses were performed. Results: A total of 307 patients were included (median age: 39 y; 58.6% male). Head CT was performed in 79.8% (n=245), revealing structural abnormalities in 43.6% (n=107). Only 3.7% (n=9) showed acute pathologic findings requiring changes in management. Most abnormalities were chronic and did not influence clinical decisions. The only variable significantly associated with acute CT findings was seizure-related traumatic brain injury (33.3% vs. 0%, P <0.001; OR=26.6, 95% CI: 11.2-62.8). Conclusions: The diagnostic yield of head CT in patients with nonindex seizures is low despite its widespread use in emergency settings. Routine neuroimaging may be unnecessary without clinical red flags such as trauma, new focal deficits, or atypical presentations. Evidence-based tools are needed to guide neuroimaging use and optimize resource utilization.