Authors :
Presenting Author: Tae Yeon Kim, MD – Portland VA HCS and Oregon Health & Science University (OHSU)
Presenting Author: David Spencer, M.D. – Oregon Health & Science University
Martin Salinsky, MD – Portland VA HCS and Oregon Health & Science University (OHSU); David Spencer, MD – Oregon Health & Science University (OHSU); Marissa Kellogg, MD, MPH – Portland VA HCS and Oregon Health & Science University (OHSU)
Rationale:
Ambulatory EEG (AEEG) can be a cost-effective and expedited alternative to gold-standard Epilepsy Monitoring Unit (EMU) admissions in evaluating patients with seizures. The yield of AEEGs has been well studied, with previous studies showing 13.3-42.7% yield depending on indication.1 While EMU studies have suggested reduced neurologic healthcare utilization in veterans diagnosed with PNES for up to three years afterwards, we are not aware of any studies showing long term utilization outcomes following AEEG.2 This study’s goal is to assess rates of repeat EEG testing following AEEG in US veterans, specifically rates of EMU admission in the 10 years following AEEG.
Methods:
A retrospective single-center cohort study of all patients who obtained an AEEG at the Portland Veterans Affairs (VA) Medical Center between the years of 2012-2014. VA administrative healthcare data on EEGs, neurology clinic visits, and hospital admissions over the nine to 11 years of patient follow-up was obtained via chart review through May 2023. Exclusion criteria included if AEEG was a repeat AEEG study or AEEG duration was <12 hours. Results:
A total of 52 AEEG studies were identified. Two were excluded due to repeat studies, in which case the index case was included in analysis. One study was excluded due to insufficient duration. A total of 49 patients were included in the final analysis. Five (10.2%) patients were female. Ages ranged from 26 to 92 years old at time of study. AEEG duration ranged from 20 to 47 hours.
Sixteen patients (32.7%) had an abnormal AEEG with one patient having a “borderline” EEG. Abnormalities included focal slowing (n=11), generalized slowing (n=3), epileptiform discharges (n=8), epileptic seizures (n=1), and surface EEG negative events (n=6). Thirty-two (65.3%) AEEGs were normal, including thirteen studies capturing surface EEG negative events.
Forty-one patients (83.7%) had an EEG prior to AEEG study: 9 (18.4%) had a prior EMU evaluation and 40 (81.6%) had prior outpatient routine EEG(s). One patient had an inpatient EEG prior to AEEG. Thirty-two (65.3%) of patients did not have any further EEGs after AEEG. In total, seven patients (14.3%) subsequently underwent EMU evaluation, of whom five patients did not have EMU evaluation prior to AEEG.
Conclusions:
We found that a minority of patients (14.3%) monitored on AEEG required subsequent EMU admission. The majority of patients (65.3%) did not have any further EEG studies after AEEG. This study suggests that AEEG can be a cost-effective tool in the evaluation of seizures and seizure like events. Future studies will compare rates of repeat EEG testing in patients who underwent AEEG vs EMU over the same period.
References:
1. Mikhaeil-Demo Y, González Otárula KA, Bachman EM, Schuele SU. Indications and yield of ambulatory EEG recordings. Epileptic Disord 2021; 23(1): 94-103.
2. Salinsky M, Storzbach D, Goy E, Kellogg M, Boudreau E. Health care utilization following diagnosis of psychogenic nonepileptic seizures. Epilepsy & Behavior 2016; 60: 107-111.
Funding:
This study received funding support from the VA Epilepsy Centers of Excellence (ECoE) and VHA Office for Academic Affiliations (OAA).