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Abstract Details

Indication and Yield of Ambulatory EEG Recordings
Epilepsy/Clinical Neurophysiology (EEG)
P6 - Poster Session 6 (12:00 PM-1:00 PM)
12-003

aEEG is increasingly ordered in the workup of patients with seizure disorders. There are no large-scale studies evaluating its indications and yield. 

To study the indications and yield of ambulatory electroencephalogram (aEEG).

This is a retrospective chart review of all Northwestern Hospital patients who underwent aEEG studies between 2013 and 2017. Indications for aEEG were classified into five categories: detection of interictal epileptiform discharges (IED), capturing clinical events, detection of subclinical seizures, quantification of known IEDs, and unclassifiable reason for study. aEEG reports were reviewed to evaluate whether the study answered the clinical question. 

A total of 1538 studies were performed. 40 studies were excluded for incomplete data and 234 for being a repeat study. A total of 1264 patients (1983 recording days) were included. Average recording days was 1.57 ± 0.73. Based on history or prior findings, patients carried the following diagnosis: 47.7% epilepsy, 11% provoked seizures, 28% paroxysmal events (PEs), and 13.3% were unclassifiable. Overall, focal IED were seen in 16.1% of studies, generalized IED in 10.8%, focal seizures in 4.1%, and generalized seizures in 1.9%.

- The most frequent indication for aEEG was evaluating IED for diagnostic purposes (48.1%). For this indication, additional information was provided by the aEEG in 19.1% of cases (11.2% focal IED, 6.4% generalized IED, 1.5% seizures without IED).
- aEEG was ordered to capture clinical events in 18.9% of the cases, mostly in patients who reported daily or weekly spells. In these, PEs without EEG correlate were captured in 36.0% whereas 7.1% had epileptic events.
- aEEG was ordered to evaluate for subclinical seizures in 17.9% of the cases; 13.3% of these studies captured seizures.

The yield of aEEG varies based on the indication for the study. aEEG can be a useful tool for capturing IED, subclinical seizures, and clinical events in the outpatient setting. 

Authors/Disclosures
Yara Mikhaeil-Demo, MD (Northwestern University, Feinberg School of Medicine )
PRESENTER
The institution of Dr. Mikhaeil-Demo has received research support from DOD/CURE TBI Consortium, Grant W81XWH . The institution of Dr. Mikhaeil-Demo has received research support from Illinois Department of Human Services (IDHS) Grant .
Karina A. Gonzalez Otarula, MD (University of South Dakota - Sanford Health) Dr. Gonzalez Otarula has nothing to disclose.
Elizabeth Cunningham Elizabeth Bachman has nothing to disclose.
Stephan Schuele, MD, FAAN (Northwestern Memorial Hospital) Dr. Schuele has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Monteris. Dr. Schuele has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Neurelis. Dr. Schuele has received personal compensation in the range of $10,000-$49,999 for serving on a Speakers Bureau for SK Life Science. Dr. Schuele has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Jazz. Dr. Schuele has received personal compensation in the range of $50,000-$99,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Journal of Clinical Neurophysiology. Dr. Schuele has received personal compensation in the range of $500-$4,999 for serving as an Expert Witness for Thomas Needham. Dr. Schuele has received research support from National Institute of Health.