Abstracts

Rationale: Juvenile Myoclonic Epilepsy (JME) is a common form of primary generalized epilepsy and is generally considered to be frequently responsive to antiepileptic drugs (80-85% of cases). We sought to estimate the prevalence of drug resistant JME in our tertiary epilepsy referral center and to identify risk factors that may lead to treatment resistance. Methods: We identified 208 patients with JME initially evaluated at the Barrow Neurological Institute (Phoenix, AZ) between 2004 and 2011 and followed up for at least 1 year. We classified observed response to treatment into three groups: I - controlled cases (N=51, 24.5%), II - pharmacoresistant cases (N= 137, 65.7%), and III - pseudoresistant cases (seizures not fully controlled but poor compliance, etc., N=20, 9.6%). The medical record for each patient was examined and scored for the presence of the following potential risk factors: gender, age of seizure onset, types of seizures (absence, myoclonic, generalized), family history of epilepsy, history of psychiatric disease, abnormalities visible in brain magnetic resonance imaging, abnormal findings on neurological exam, and the presence of any other risk factors for development of seizures (e.g. history of significant head trauma, premature birth, febrile seizures). We used a step-wise analysis of variance (ANOVA) to identify risk factors which were significant predictors of treatment resistance (?², p<0.05) and Fischer s Exact Test (p<0.05) to compare rates of categorical outcomes.Results: Patient characteristics: 83 men, 125 women; mean age 29.7 years (range 16-68), mean age of onset 11.3 years (1-33). Excluding the pseudoresistant cases, the ratio of resistant cases to controlled cases was significantly (p=2.2 x 10-16) different from the ratio reported in previous studies (Gelisse et al. 2001). Step-wise ANOVA showed that both seizure type (p=0.004) and gender (p=0.039) were significant predictors of treatment resistance. Amongst seizure types, the presence of all three seizure types was the one combination significantly contributing to this prediction. Conclusions: In comparison to previous studies examining the prevalence of drug resistant JME patients, our study shows a much higher prevalence. Although the prevalence of resistant cases may be increased at our referral epilepsy center compared with that in the community, the prevalence is still significantly higher than reports from other tertiary centers. This suggests that the prevalence of pharmacoresistant JME may be much higher than previously reported. This study also found that patients who experience all three types of seizures characteristic of JME are significantly more likely to have treatment resistant JME.