Abstracts

Rationale:
Ambulatory electroencephalography (AmEEG) has been widely utilized to evaluate patients with seizures or seizure-like events. It can provide useful information to distinguish epileptic vs. nonepileptic seizures and localizing seizure focus. AmEEG may be used in lieu of more costly inpatient video-EEG monitoring (EMU) test or an extension of inpatient EMU when the EMU does not provide sufficient information due to a lack of captured events. The primary purpose of this study was to evaluate the usefulness of AmEEG in epilepsy care.
Method:
A chart review of patients was performed retrospectively, who underwent AmEEG from April 2015 to August 2018. A portable, ambulatory 24-channel EEG system was used with a standard 10-20 electrode system placement. Each patient was recorded continuously in an outpatient setting for 24-72 hours. A clear instruction was provided to each patient when to press the ""event"" button and how to keep an event diary throughout the study. No anti-seizure medication changes were made during AmEEG monitoring. The recorded data were analyzed at the conclusion of the study for each patient.  
Results:
A total of 58 patients were identified during the designated study period (69% woman). The mean age of patients was 41.8 years (17-78 years). Twenty-three patients (39.7%) had AmEEG as an extension of inpatient EMU due to a lack of stereotypical events captured. The remaining patients did not have prior EMU monitoring. 79.3% had 72-hour EEG recordings, and the rest had less than 72 hours but at least 24 hours. Twenty-seven patients (46.5%) reported their typical events during the recording. Most of them (96.3%) had nonepileptic spells. Thirteen patients had interictal discharges, which included focal discharges or intermittent slowing (61.6%), generalized discharges (23%), asymmetric background slowing only (7.7%), generalized slowing (7.7%). Among 23 patients with prior EMU monitoring, 34.7% reported typical events, and all these reported events were nonepileptic spells. It was decided that 32.7% of total AmEEG cases had provided sufficient information to establish a specific diagnosis.
Conclusion:
AmEEG may provide useful information toward specific seizure diagnosis in about one-third of the cases. Even though the study duration was 72 hours or less, stereotypical events were reported in approximately one half (46.5%) of the patients. However, most commonly reported events were not epileptic seizures. Overall, our study indicates that AmEEG can be a useful alternative tool if inpatient EMU monitoring is not feasible.
Funding:
:No funding