Abstracts

Inpatient, video-EEG monitoring is often considered the [quot]gold standard[quot] for evaluating patients with medically refractory epilepsy. Access to inpatient epilepsy monitoring units is improving as more non-academic centers are providing this service. There are still large numbers of patients for whom access is a major barrier. We evaluated the diagnostic utility of ambulatory, digital video-EEG monitoring in patients with refractory [quot]epilepsy[quot] without access to an in-patient monitoring unit. Data from a consecutive cohort of fifty patients with a presumptive diagnosis of medically refractory epilepsy for whom ambulatory video-EG monitoring was ordered were retrospectively analyzed. A study was considered [quot]positive[quot] if typical spells were recorded, epileptic or not, or if inter-ictal (ii)EEG abnormalities were identified which clarified seizure type when prior baseline EEGs were normal. [quot]Negative[quot] studies were those where no spells were recorded or when the iiEEG provided no additional data compared to prior EEGs. Of the 50 patients, 36 underwent testing for diagnostic purposes and 14 for presurgical screening. Mean evaluation period was 2.2 days. Mean number of seizures recorded per patient was 3. Positive diagnostic information was obtained in 60% of studies. In the diagnostic group, positive yield was 53%. The yield in the presurgical group was 78.5%. No seizures were recorded in 46% of patients (n=23), but of these, 30% had iiEEG abnormalities that helped clarify diagnosis, and hence were considered diagnostic. Medical management was changed on the basis of the ambulatory video-EEG study in 60% of patients. The development of ambulatory, digital video-EEG monitoring can allow for diagnosis, seizure classification and even presurgical screening for patients without access to in-patient monitoring. In addition, the ambulatory video-EEG study may be appropriate for some patients who might find it difficult to comply with in-patient monitoring, such as pediatric patients, patients with heavy smoking, child care issues or in those where it is thought that environmental stimuli are triggers for targeted episodes. The shorter monitoring duration maybe responsible for the slightly lower rate of [ldquo]positive studies[rdquo] compared to recent studies looking at this issue in in-patient monitoring¹, but the cost savings is substantial. Therefore, for many patients, ambulatory digital video-EEG monitoring is a cost-effective alternative to in-patient video-EEG studies.
¹Ghougassian D. F., et. al., Epilepsia 45(8):928-932, 2004 (Supported by SleepMed/DigiTrace (Peabody, MA 01960).)