Abstracts

Rationale: Patients with juvenile myoclonic epilepsy (JME), a common subtype of idiopathic generalized epilepsy (IGE), generally have a good response to appropriate antiepileptic drugs (AEDs), but in others the disease remains refractory to drug treatment. Focal EEG abnormalities including focal slowing or epileptiform discharges and EEG asymmetries are associated with such drug resistance in patients with JME. However, the predictability of such abnormalities towards drug resistance remains controversial. We investigated the relationship between focal epileptiform EEG abnormalities (FEAs) and drug resistance in patients with JME as well as other types of IGE. Methods: A total of 430 patients were diagnosed with epilepsy based on 4-day video EEG monitoring (VEM) in our epilepsy monitoring unit from September 2010 to December 2014. Thirty-seven patients were diagnosed with IGE. They were followed for at least 1 year after VEM in our outpatient clinic. Of those, the final sample for this study included 24 patients (12 men and 12 women, aged 14-56 years) who achieved seizure freedom for 1 year or longer with appropriate medication. The VEM data of the 24 patients were retrospectively reviewed to evaluate the presence of FEAs. FEA was defined as a single regional spike or a regional spike preceding a generalized spike and wave complex. AED loads at the final visit were used to evaluate the level of drug resistance in patients with IGE. AED loads were calculated as the sum of prescribed daily dose/defined daily dose ratios for each co-prescribed AED. Data were analyzed using Welch's t-test. Results: Among 24 seizure-free patients, 13 patients with interictal FEAs had significantly higher averaged AED loads than the 11 patients without FEAs (1.38 vs. 0.61, p = 0.005). In the subgroup of 12 patients with JME, 7 patients with interictal FEAs had significantly higher averaged AED loads than the 5 patients without FEAs (1.57 vs. 0.29, p = 0.004), whereas the 12 patients with other types of IGE did not show such significant differences. Two of the 7 patients with JME had both ictal and interictal FEAs, and higher AED loads than the 5 patients without ictal FEAs, although not significantly (1.81 vs. 1.48, p = 0.732). Conclusions: Patients with JME suffering interictal FEAs required significantly higher AED loads for seizure control than patients without FEAs. This correlation was only seen in JME and not in other types of IGE. The presence of interictal FEAs may be a predictor of drug resistance in patients with JME. Funding: none