Abstracts

Rationale: Psychogenic nonepileptic seizures (PNES) coexisted with epilepsy in up to half of the patients, but are distinguished from epileptic seizures by lacking abnormal epileptiform discharges in EEG. The presence of interictal epileptiform discharges (IEDs) on EEG is helpful in making the diagnosis of epilepsy in patients with PNES.We aim to study the relationship between duration of video-EEG and detection IED in patients with PNES and epilepsy. Methods: This is a retrospective case series study. Data were extracted from adult patients with confirmed epilepsy admitted to epilepsy monitored unit at King Faisal Specialist Hospital and research center - Jeddah, from January 2010 to December 2017.  Data collected included demographics, duration of epilepsy, number of antiepileptic drugs (AEDs), length of stay in the EMU and history of psychiatric disorder. Patients with incomplete data or those admitted and found to have PNES only were excluded. Results: Four hundred seventy-seven patients were admitted to the EMU during the study period and were confirmed to have epilepsy. Only 34 patients (7%) were found to have PNES. Out of those 29 were women (85%), the mean age of 27.8 years (range; 12 – 49 years). The mean duration of epilepsy was 13.8 years, (range; 1- 43 years). Majority of patients were on AEDs (91%), with an average of 1.7 AEDs. A known history of psychiatric disorder was identified in half of the patients (17 cases), most of them had mood disorders (15 patients).  The average EMU stay was 5.2 days (range; 2-10 days, SD = +/- 2.1 days). IEDs were detected in 15 patients (44%).  The likelihood of detecting IEDs increased by 64% for each additional day the patient stayed in the EMU (adjusted OR= 1.64, 95%CI; 1.1 - 5.5, p-value = 0.04), adjusted for patient’s age, gender, duration of epilepsy, the presence of a psychiatric disease, number of AEDs, and recording ictal changes.  Neither the absence of a psychiatric disorder nor the psychiatric diagnosis can predict the presence or absence of IEDs. Conclusions: The likelihood of recording IEDs in epilepsy patients with PNES is proportionate to the length of stay in the EMU, regardless of the presence or absence of a known psychiatric disorder. The exact number of days needed to confirm this observation remains to be determined. Funding: None