Why Are Patients With Absence Seizures Absent? A Brain Imaging Study

The fundamental mechanisms of altered brain function and impaired attention in childhood absence epilepsy (CAE) are not known. Absence seizures consist of brief 5-10 seconds episodes of unresponsiveness, associated with a 3-4 Hz "spike-wave" discharge on electroencephalogram (EEG). CAE affects 10-15% of children with epilepsy. In addition to the deficit during seizures, many children also suffer from milder attention impairment between absence episodes, which may not be due entirely to medications. Impaired attention during and between absence seizures has a major negative impact on patient quality of life due to deficits in school performance, potential for injuries, and social stigma.

Recent studies suggest that impaired cognition in so-called "generalized" absence seizures may, in fact, depend on dysfunction in specific brain networks. Our central hypothesis is: abnormal function in focal brain regions, such as the anterior cingulate/medial prefrontal cortex and medial thalamus, causes impaired attention both during and between seizures in CAE. If confirmed, this may lead to innovative regional therapies targeted at improving impaired attention in CAE. Specifically, we hope to determine which specific cortical and sub-cortical networks are selectively involved when patients show impaired attention. Using simultaneous EEG and functional magnetic resonance imaging (fMRI), we will determine which brain regions are involved in absence seizures while using a continuous performance task (CPT) to test attention vigilance in the same patients. A few neuropsychology tests will then follow. Patients will be reimbursed $100 as well as all travel and parking expenses.

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