The Diagnostic Utility of Ambulatory EEG Following Nondiagnostic Epilepsy Monitoring Unit Admissions

Abstract

Purpose: Epilepsy monitoring unit (EMU) admissions provide a definitive diagnosis for approximately three-quarters of patients. However, many patients do not receive a definitive diagnosis following EMU admission. Ambulatory EEG following nondiagnostic EMU admissions was evaluated as a means of providing a diagnosis for these patients. Methods: In this retrospective study, we performed a chart review of 62 pediatric and adult patients who had a 72-hour ambulatory EEG following a nondiagnostic EMU admission. Results: In total, there were 62 patients with nondiagnostic EMU admissions who subsequently underwent ambulatory EEG. Mean age was 33.8 (SD, 18.5) years. Forty-one patients (66.2%) were female and 46 (74.2%) adult. Fifty patients (80.7%) had an additional comorbid neurologic, somatoform, or psychiatric diagnoses. Of the original 62 patients, 32 (51.6%) had no events, 3 (4.8%) had events with and without EEG changes, 4 (6.5%) had only events with EEG changes, and 23 (37.1%) had only events without EEG changes. Ambulatory EEG thus provided clinically useful information in 30 (48.4%) cases, with 20 (66.7%) reaching diagnosis within 24 hours. Conclusions: Ambulatory EEG following a nondiagnostic EMU admission may yield positive results in approximately half of all patients. A substantial proportion of the events that were captured in this setting were without EEG changes. In the absence of video and supportive clinical information, these events not only may represent nonepileptic events but also could represent focal seizures without EEG changes. The presence of particular stressors in the home environment may explain why many patients, specifically those who are nonepileptic, had events relatively quickly following discharge.

The Yield of Ambulatory EEG-Video Monitoring

“…Another study found that 32.3% of total sample reached a diagnosis within 24 hours, whereas the remaining patients who had events were equally distributed across the subsequent 24-hour intervals. 5 The diagnostic yield of such studies within the time collected remains undetermined. Kandler et al 17 found comparable diagnostic yield of ambulatory EEG-video (67%) to inpatient EEG-video monitoring (63%).…”

“…EEG-video recording is the mainstay of epilepsy centers; however, epilepsy monitoring units (EMU) frequently have long backlogs, waiting periods, and require patients to be in-hospital for several days. 1 To date, most literature on ambulatory EEG monitoring refers to EEG without video [2][3][4][5][6][7][8][9][10][11] and EEG-video has long been assumed to be an inpatient procedure. As of the past decade, technology has made ambulatory EEG-video possible.…”

How much time is enough? Establishing an optimal duration of recording for ambulatory video EEG

“…Fox et. al 12 notes in a small sample of patients with previously nondiagnostic EMU stays (n = 62), half of the sample had sufficient diagnostic information by the end of 72 hours of ambulatory EEG, with 32.3% reaching a diagnosis within 24 hours, and the remaining equally distributed over the following two 24‐hour blocks. Primiani et.…”

Past, Present and Future of Home video‐electroencephalographic telemetry: A review of the development of in‐home video‐electroencephalographic recordings

“…Synergies of combining both and achieving a higher diagnostic yield have been demonstrated. 17 With the current electrode technology that is available, HVET recordings are limited to several days, often enough to obtain conclusive data to make a diagnosis. Repeat recordings may be required, but drug withdrawal in HVET, which is routine in the EMU, has not yet been attempted due to safety concerns.…”

“…The integration of hospital‐based services with non–hospital‐based services remains a fruitful ground for collaboration and innovation. Synergies of combining both and achieving a higher diagnostic yield have been demonstrated 17 …”