RESUMEN
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-naïve 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.