Abstracts

Rationale:
Childhood absence epilepsy is a relatively homogeneous, genetic epileptic syndrome with a benign, self-limiting course.  In our previous work, we identified 3 phases in seizure resolution based on EEG changes.  In the early phase, 3 Hz spike and wave bursting became shorter and less frequent.  This evolved into isolated frontal discharges with poor propagation.  In this study.  We define, in more detail, the nature and timing of these early EEG changes in a cohort of children with classic 3 Hz CAE during the first 2 years of treatment.
Method:
Patients were selected that met standard criteria for CAE.  They were followed progressively with serial, biannual EEGs over the course of their disorder.  Both routine and 24-hour continuous video-EEG monitoring were used to ensure comprehensive review of both wakefulness and sleep.  Patients were treated with ethosuximide or valproate to control seizure activity.
Results:
We studied 32 patients with CAE, ages 5-11 years old (mean = 7.6) at diagnosis.  All showed 3 Hz spike and wave bursts on their initial EEG. Bursting occurred several times on the initial study with durations from 2-14 sec. (mean=6.5). Bursting was present but reduced in 40% of the second EEGs done 5-8 months later.  In these, duration of bursts decreased to 1-6 sec. (mean=1.8). The EEGs in the remaining 60% of patients showed either isolated frontal or central discharges in 1/3 or normal studies in the other 2/3 of patients. By one year of treatment, only 37% showed bursting (daytime bursting disappeared before nocturnal bursts) and 50% showed fragmented isolated discharges or increased vertex wave activity. Included in these numbers are patients who had previously shown normal EEG studies at the half-year mark. None of them had a consecutive second normal EEG.  By 2 years, bursting was present in only 24% of patients.  About 65% of EEG patient's showed bifrontal or central isolated discharges.
Conclusion:
Seizure resolution in CAE is a time-dependent process that occurs over 2 years or more. Bursting declined from 100% in the initial EEGs to 37% of EEGs done one year later and only 24% by 2 years.  Isolated regional discharges were the predominant EEG pattern after 2 years of treatment.  These EEG changes reflect significant changes in the activation of different neuronal pathways and provide an important window on the early stages of seizure resolution in CAE.
Funding:
:No special funding