Focal EEG features and therapeutic response in patients with juvenile absence and myoclonic epilepsy

Objective To investigate the characteristics of focal EEG features in patients with juvenile absence epilepsy (JAE) and juvenile myoclonic epilepsy (JME), and to assess their possible influence on therapeutic response. Methods Focal EEG features were prospectively scored in 168 consecutive patients. Ninety-six patients were drug-naive and 72 patients were already on antiepileptic drugs (AEDs): 38 on adequate medication and 34 on inadequate medication. Therapeutic response was assessed one year after starting adequate therapy. Results One-hundred-eighteen patients (70.2%) had focal EEG features: 89 patients (53%) had focal epileptiform discharges, and 80 patients (47.6%) had focal slowing. Most often, these were multifocal and localized in frontal and temporal regions. Among patients already on AEDs, patients with focal EEG features were more often treated with inadequate medication due to misdiagnosis, than patients without focal features. Data on therapeutic response were available for 118 patients; most of them (90.7%) were seizure free. None of the focal EEG features affected therapeutic response. Conclusion Focal EEG features are common in patients with JME and JAE, but they do not influence the therapeutic response. Significance It is important that physicians are aware of the focal EEG features in order to avoid misdiagnosis and inadequate therapy.