Long-term EEG Utilization After Ambulatory EEG (aEEG) versus Epilepsy Monitoring Unit (EMU) Admission in US Veterans
Tae Yeon Kim1, Jacqueline Hirschey1, Martin Salinsky1, David Spencer1, Marissa Kellogg2
1Neurology, Oregon Health & Science University, 2VA Portland Healthcare System, Dept of Neurology
Objective:
To compare long-term EEG utilization rates between veterans monitored with aEEG and those admitted to EMU.
Background:
AEEG is a cost-effective alternative to gold-standard EMU for seizure evaluation. Few studies have evaluated long-term rates of EEG utilization following aEEG testing.
Design/Methods:
Retrospective cohort of all patients who underwent a first aEEG longer than 12 hours at a VA hospital between 2012-2014 or were admitted to the EMU in 2013. Data on EEGs and neurology clinic visits over the 9-11 years of patient follow-up was obtained via chart review.
Results:
49 aEEG and 59 EMU studies met study criteria. Among aEEG patients, age ranged from 26-92 years, and study duration ranged from 20-47 hours. Among EMU patients, age ranged from 23-76 years, and study duration was 1-11 days. 10.2% of patients were female.
Yield of abnormal findings was 16/49 (32.7%) by aEEG compared to 21/59 (35.6%) by EMU. Epileptic seizures were captured in one aEEG study compared with nine EMU studies (2.0% vs 35.6%). Surface EEG-negative events were captured in six aEEG studies (12.2%) compared with 34 EMU studies (57.6%).
Prior EEG testing had been performed in 41 aEEG patients (83.7%) vs 40 EMU (67.8%). Prior EMU admissions were conducted in 9 (18.4%) aEEG patients vs 11 (18.6%) EMU patients. Subsequent EMU evaluation was performed in 7 (14.3%) aEEG patients (5 without prior EMU) vs 5 (8.5%) EMU patients. No further EEG testing was performed in 32 (65.3%) aEEG patients compared to 44 (74.6%) EMU patients over the 10-year study period.
Conclusions:
Veterans monitored by aEEG were similar to those monitored in the EMU with regard to subsequent EMU evaluation (14.3% vs 8.5%). Most patients monitored by aEEG (65.3%) and EMU (74.6%) did not undergo repeat EEG, suggesting that aEEG can be a cost-effective tool in the evaluation of seizures.