PracticeUpdate Neurology February 2019

EDITOR’S PICKS 14

Generalized Polyspike Train as EEG Biomarker of Drug-Resistant Idiopathic Generalized Epilepsy Neurology Take-home message • Drug resistance is seen in about one-third of patients with idiopathic generalized epilepsy (IGE), and there are no reliable indicators to predict its occurrence. This study sought to identify biomarkers of drug resistance in IGE. An in-depth EEG analysis was used to identify patterns in a discovery cohort, and the findings were then examined in an independent replication cohort. On multivariable analyses, the two factors associated with drug resistance were higher number of seizures ever experienced (OR for 3 vs 1, 31.1) and generalized polyspike trains during sleep (OR, 10.8). Only the latter factor was associated with drug resistance in the replication cohort, with the generalized polyspike trains present in 45.5% of drug-resistant patients and 17.2% of drug-responsive patients (OR, 4.0). • The results suggest that this EEG pattern can help identify patients with drug-resistant epilepsy in this population. Codrin Lungu MD Abstract

female; median age 27.5 years), the proportion of patients with generalized polyspike train dur- ing sleep was also higher in the drug-resistant group (OR = 4.0, 95% CI: 1.35-11.8, p = 0.012). CONCLUSION Generalized polyspike train dur- ing sleep may be an EEG biomarker for drug resistance in adults with idiopathic generalized epilepsy. Generalized Polyspike Train: An EEG Biomarker of Drug-Resistant Idiopathic Generalized Epi- lepsy. Neurology 2018 Nov 06;91(19)e1822-e1830, Y Sun, U Seneviratne, P Perucca, et al. www.practiceupdate.com/c/75947

RESULTS The discovery cohort included 85 patients (29% drug-resistant and 71% drug-re- sponsive). Their median age at assessment was 32 years and 50.6% were female. Multivariable analysis showed that higher number of seizure types ever experienced (3 vs 1: odds ratio [OR] = 31.1, 95% confidence interval [CI]: 4.5-214, p < 0.001; 3 vs 2: OR = 14.6, 95% CI: 2.3-93.1, p = 0.004) and generalized polyspike train (burst of generalized rhythmic spikes lasting less than 1 second) during sleep were associated with drug resistance (OR = 10.8, 95% CI: 2.4-49.4, p = 0.002). When these factors were tested in the replication cohort of 80 patients (27.5% drug-resistant and 72.5% drug-responsive; 71.3%

OBJECTIVE To identify clinical and EEG biomark- ers of drug resistance in adults with idiopathic generalized epilepsy. METHODS We conducted a case-control study consisting of a discovery cohort and a rep- lication cohort independently assessed at 2 different centers. In each center, patients with the idiopathic generalized epilepsy phenotype and generalized spike-wave discharges on EEG were classified as drug-resistant or drug-re- sponsive. EEG changes were classified into predefined patterns and compared between the 2 groups in the discovery cohort. Factors associated with drug resistance in multivariable analysis were tested in the replication cohort.

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