Patients with Focal Epilepsy but without Interictal Epileptiform Discharges (P4.068)

Objectives: The interictal epileptiform discharges (IEDs) in human epilepsies are crucial for diagnosis of epilepsy and indentify different epileptic syndromes but, not all patients show IEDs on their EEGs. In this study we are evaluating patients with focal epilepsy but no IEDs during prolonged EEG-video monitoring (VEM). Methods: We did a retrospective review of VEM of all patients whom were admitted to the seizure monitoring unit (SMU) in the Calgary Epilepsy Program between Jul 2010 and Aug 2015. We included Adult patients with Focal Epilepsy base on diagnostic criteria of International League Against Epilepsy (ILAE) who had at least 3 days of VEM and had at least one epileptic seizure recorded. Result: Among a total of 706 patients admitted to SMU, 293 patients fulfilled our inclusion criteria. Fifty-five (19[percnt]) of these patients (34 males) with an average duration of 8.7.days of VEM showed no IEDs (non-spikers) and 238 (104 males) with an average duration of 10.1days of VEM had IEDs(spikers). The non-spikers had an average age and duration of epilepsy of 35 and 10 years while these were 45 and 20 years for spikers. The most frequent seizure focus was in temporal lobe (53[percnt] in non-spikers Vs. 58[percnt] in spikers). 45 ([percnt]) of non-spikers had epileptogenic lesion on their MRI while this was seen in 60([percnt]) of spikers. 9([percnt]) of non-spikers and 12.6([percnt]) of spikers had a respective epilepsy surgery. Conclusion: Almost 1 in five patients with focal epilepsy show no IEDs despite prolonged VEM. These patients, compare to the patients with IEDs, more frequently were male (62[percnt] Vs 44[percnt]) had shorter duration of epilepsy (10 Vs 20 years) but the average age, most common seizure focus, lesional Vs non-lesional, seizure intractability and seizure freedom rates were not significantly different between these two group of patients with focal epilepsy. Disclosure: Dr. Shariatzadeh has nothing to disclose. Dr. Agha-Khani has nothing to disclose. Dr. Wiebe has nothing to disclose.