Abstracts

Idiopathic generalized epilepsy syndromes (IGES) constitute 20-40% of all epilepsies. Up to a third of cases are diagnosed after the second decade of life1. The prognosis of IGES in the non-pediatric setting may vary from that in infants and children because of differences in genetic, environmental and lifestyle factors. All patients diagnosed with IGES at the Epilepsy Unit, Western Infirmary, Glasgow, Scotland, between 1981 and 2001 were included in the study. Demographic and clinical data, including syndrome classifications and pharmacological outcomes, were collated by a review of casenotes. Response to treatment was defined as complete control of seizures for 12 months. Patients remaining seizure free to the end of follow up were considered to be in remission. Of 780 patients diagnosed with epilepsy over the 20 year period, 105 (13%) met the clinical and electroencephalographic (EEG) criteria for IGES. The median age at onset was 17 years (range 5-51). Syndromes included Juvenile Myoclonic Epilepsy (JME, n=55), Epilepsy with Generalized Tonic-Clonic Seizures (GTCS) Only (n=28), Epilepsy with GTCS on Awakening (n=7), Juvenile Absence Epilepsy (n=4), Epilepsy with GTCS during sleep (n=3), Late Onset Myoclonic Epilepsy (n=3), Childhood Absence Epilepsy (n=2) and Epilepsy with Myoclonic Absences (n=1). Overall, 76 (74%) patients responded to treatment. Sixty-six (64%) of these attained remission, which was achieved with antiepileptic drug (AED) monotherapy in 56 (54%) cases. The responder rate in the whole cohort with valproate (66%) was higher than with lamotrigine (45%), but this difference did not reach statistical significance (p=0.076). In patients with JME, however, valproate was significantly more likely to produce remission (75%) than lamotrigine (39%; p=0.014). The effect of age at onset, gender, family history of epilepsy, history of febrile seizures, psychiatric co-morbidity, epileptiform abnormalities on EEG and seizures types on treatment outcomes was analysed by logistic regression. History of febrile seizures was the only factor that was significantly associated with reduced probability of remission (Odds ratio 0.18; 95% CI 0.03-0.96) IGES constituted 13% of cases in a largely adult cohort of newly diagnosed epilepsy. Approximately 2/3 of these patients achieved remission with AED therapy, mostly with a single drug. Valproate appeared to be the most efficacious drug, especially in JME. Previous febrile seizures were associated with reduced likelihood of remission, which could imply a genetic component to pharmacoresistant IGES.
Reference:
1. Marini C, King MA, Archer JS, Newton MR, Berkovic SF. Idiopathic generalised epilepsy of adult onset: clinical syndromes and genetics. J Neurol Neurosurg Psychiatry 2003; 74: 192-196.