Abstracts

Rationale: Long-term video EEG has become a standard of practice in epilepsy centers for characterization of paroxysmal spells and for surgical work up in intractable epilepsy cases. However in this era of healthcare reform it is important to understand the yield of this expensive diagnostic modality. Methods: This is a retrospective chart review of the last 200 patients who were admitted to the Epilepsy Monitoring Unit (EMU) at our University Epilepsy Center. Patients who did not complete the study were excluded. 174 studies were found eligible. All studies were screened by senior EEG technician and read by the staff epileptologist. Under the standard protocol followed in our EMU antiepileptic medications were not tapered till the patient is admitted to the EMU. If no events were recorded, provocative maneuvers like sleep deprivation, photic stimulation and hyperventilation were done. On chart review, we looked at patient demographics, time to first event, number of events recorded and the final diagnosis on the characterization of the events. Results: 174 studies were reviewed in the analysis. There were 56% females and 44% males in the age range of 15 to 76 years, with mean of 41 years. Recording time ranged from 1 to 6 days with mode of 4 days. The study was diagnostic in 130 patients (74.7%). 42% had only non-epileptic events (NEE) while 26% had epileptic seizures (ES). 4.6% had both ES and NEE. 4 patients had interictal discharges diagnostic of generalized epilepsy though no events were recorded. 0 to >20 events were recorded per study with median of 3 events. Time to first event ranged from 0.5 to 90 hours. Median time to first event was 23.5 hours with a mean of 28.3 hours. In 64 (41%) patients, events occurred within 24 hours while in 12 (8%) the first event was recorded after 72 hrs. Mean time for Epileptic Seizures was 33.7 hours while for NEE was 23.2 hours. No interictal epileptiform discharge (IED) was noted in 21% of patients diagnosed with epilepsy. Conclusions: The yield of video-EEG monitoring in an adult EMU was found to be 74.7%. This finding directly impacts the management of patients with epilepsy. The average time to first event was 28.3 hours. However, in 8% cases, more than 3 days of monitoring was needed to obtain an accurate diagnosis. Interictal epileptiform discharges alone cannot reliably distinguish ES and NEE in all cases. Thus Video-EEG monitoring has a high diagnostic yield and is an essential test in the appropriate patient population for providing the highest quality of epilepsy care.