Interictal and ictal video-EEG monitoring

Purpose : The purpose of this paper is to demonstrate the diagnostic effica cy and therapeutic relevance of video-EEG monitoring in an large patient po pulation with long-term follow-up. Patients and methods: Between October 1990 and May 1997, 400 patients were monitored at the Epilepsy Monitoring Unit (EMU) of the University Hospital in Gent. In all patients, the following parameters were retrospectively exa mined : reason for referral, tentative diagnosis, prescribed antiepileptic drugs (AEDs) seizure frequency, number of admission days, number of recorde d seizures, ictal and interictal EEG, clinical and electroencephalographic diagnosis following the monitoring session. During follow-up visits at the Epilepsy Clinic, we prospectively collected data on different types of trea tment and post-monitoring seizure control. Results: 255/400 (64%) patients were referred for refractory epilepsy. 145/ 400 (36%) patients were evaluated for attacks of uncertain origin. Mean fol low-up, available in 225 patients, was 28 months (range: 680 months). Mean duration of a single monitoring session was 4 days (range: 2-7 days). Prolo nged interictal EEG was recorded in all patients and ictal EEG in 258 (65%) patients. Following the monitoring session, the diagnosis of epilepsy was combined in 217 patients. Pseudoseizures were diagnosed in 31 patients (8%) AEDs were started in 19 patients, stopped in 6 and left unchanged in 110. The type and/or number of AEDs was changed in 111 patients. Sixty patients underwent epilepsy surgery. In 48 surgery patients, follow-up data were ava ilable, 29 of whom became seizure-free, and 16 of whom experienced a greate r than 90% seizure reduction. Vagus nerve stimulation was performed in 11 p atients, 2 became seizure-free, and 7 improved markedly. Of the non-invasiv ely treated patients in whom follow-up was available (n = 135), 70 became s eizure-free or experienced a greater than 50% reduction in seizure frequenc y; 51 patients experienced no change in seizure frequency. Outcome was unre lated to the availability of ictal video-EEG recording. In patients with co mplex partial seizures, seizure control was significantly improved when a w ell-defined ictal onset zone could be defined during video-EEG monitoring. Conclusion: Prolonged intel ictal EEG monitoring is mandatory in the succes sful management of patients with refractory epilepsy. Ictal video-EEG monit oring is very helpful but not indispensable, except in patients enrolled fo r presurgical evaluation or suspected of having pseudoseizures.