Purpose: This study aims to assess the diagnostic yield of routine EEG (rEEG) followed by long-term ambulatory EEG (aEEG) in a retrospective cohort, focusing on the rates of abnormal EEG findings, and overall event capture.
Methods: Data were retrospectively collected from deidentified clinical reports of patients who underwent both rEEG and subsequent aEEG, with both modalities including video recordings. The study included 95 patients, with demographic, clinical information, and EEG findings extracted for analysis. Statistical analyses included chi-squared proportion tests and Wilcoxon rank-sum tests to assess the influence of variables such as age, sex, referral source, and aEEG duration on outcomes. Bayes factors were calculated to evaluate the power of the statistical tests.
Results: Among the 95 patients, 33 % were 16 years old or younger. The median duration of aEEG was 3.9 days. Abnormal EEG findings increased from 18 % with rEEG to 33 % with aEEG. Epileptic seizures were captured in 3 % of rEEG and 8 % of aEEG, while non-epileptic events were captured in 35 % of aEEG compared to none in rEEG. Younger age was associated with higher rates of abnormal findings, but this was not adequately powered. Females had a higher likelihood of event capture on aEEG, though this finding was also underpowered. The majority of adult and paediatric patients with a normal rEEG went on to have a normal aEEG.
Conclusion: Ambulatory EEG significantly improves the diagnostic yield for both epileptic and non-epileptic events compared to routine EEG, particularly in adults. This study supports the broader use of aEEG for comprehensive epilepsy evaluation and suggests further research to optimise its clinical utility.
Keywords: Clinical yield; Interictal epileptiform discharges; Seizures; ambulatory EEG; routine EEG.
Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.