Abstracts

Rationale: The purpose of the study was to evaluate the semiology and clinical characteristics of patients with generalized spike-wave discharges suggestive of Absence Seizures (AS), and focal epileptic discharges on EEG. Methods: We identified 16 consecutive patients with Absence Seizures by clinical and EEG criteria, who also had focal spikes on initial or subsequent EEG. Patients that had atypical generalized spike-wave discharges with Atypical Absence Seizures (AAS) were also included in this study.Results: Age at presentation ranged from 18 months to 12 years, mean 5 years, with 9/16 boys and 7/16 girls. Duration of follow up ranged from 6 months to 9 years, mean 2.7 years. 7/16 of the patients had head imaging, and all imaging was benign. EEG characteristics included typical 3 Hz Generalized Spike and Wave in 14/16, Irregular Generalized Spike and Wave in 2/16 (both had Absence seizures) and focal spikes in all 16 patients (2 patients with spikes suggestive of BECTS). Locations for focal spikes included frontal, central, temporal, parietal with no clear predominance in locations. 88% (14/16) of the patients are developmentally normal, one is in special classes and one is speech delayed. 38% (6/16) of the patients seizures are controlled on current antiepileptic therapy, and the remaining (10/16) are refractory. 63% patients (10/16) had AS or AAS on initial presentation. Other presenting semiologies were GTCs (4/16), complex partial seizures (CPS) (1/16), and atonic seizures (1/16). 16/16 patients had Absence Seizures as one of their seizure semiologies and 50% (8/16) had another semiology as well, 4 with AS and GTCs, 1 with AS, GTCs, and myoclonus, 1 with AS, GTCs, and simple partial seizures, 1 with AS and CPS, and 1 with AS and atonic seizures. Of the eight patients with AS and an additional seizure semiology, only 3 (38%) were controlled on current antiepileptic therapy, Valproate or Topiramate +Levetiracetam. Of the 7 patients with only absence seizures, four (57%) are well-controlled on current antiepileptic therapy, three with ETX monotherapy and one with combination ETX and LEV. Both patients with developmental delay have two different seizure types and are refractory to current treatment. Conclusions: 1.Patients with focal spikes in addition to Absence Seizures have a high likelihood of having additional seizure semiologies (50%) and these patients had lower seizure control rates (38%) in our cohort. 2.The remission rates for patients who had only Absence Seizures was higher (57%) in this group but similar when compared to published data for typical Childhood Absence Epilepsy patients (56-84%). 3.Although focal spikes were observed in all these patients, complex partial seizures occurred in only 1 patient. It is possible that some of the GTCs were focal onset with secondary generalization but this could not be confirmed by history. 4.The significance of these findings needs to be further elucidated and it remains unclear whether these patients have co-existing idiopathic generalized epilepsy and focal epilepsy or whether the generalized epilepsy represents secondary bilateral synchrony.