TYPICAL ABSENCES: RESULTS OF OWN INVESTIGATIONS

Abstract

Typical absences (TA) are brief primary generalized epileptic seizures characterized by sudden onset and termination. According to their definition, absences consist of impairment of consciousness that is synchronously accompanied by electroencephalographic (EEG) changes as generalized spike–slow wave discharges of 3 or more Hz. The authors conducted an investigation of 1261 patients with different forms of epilepsy with onset of seizures from the first days of life to the age of 18 years. The patients were followed up from 1990 to 2010. Absence seizures were detected in 231 patients, which accounts for 18.3 % of all the epileptic patients. TA were found in 102 patients, which constitutes 8.1 % of all cases of epilepsy with onset of seizures beyond the age of 18 years. The paper provides a detailed analysis of a group of patients with TA in terms of anamnestic, clinical, electroencephalographic, and neuroimaging features and the results of therapy with antiepileptic drugs (AEDs). The age of onset of TA-associated epilepsy was from 9 months to 17 years (mean 9.4 ± 4.06 years). The disease occurred most frequently in young school-age children (41.2 %). Isolated TA as the only type of seizures were observed in the clinical picture of 28 (27.5 %) patients. TA were concurrent with other types of seizures in other cases. The investigators have identified 4 types of seizures which TA (generalized convulsions, myoclonic seizures, febrile seizures, and eyelid myoclonia) may be concurrent with. Neuroimaging stated there were no brain changes in 85.3 % of TA-associated epilepsy cases. Moderate diffuse subatrophic changes were detected in other cases (14.7 %). Local cerebral structural abnormalities were absent. The use of antiepileptic therapy as both monotherapy and polytherapy using different combinations showed the high efficacy of AEDs. Complete remission was achieved in 84.3 % of TA-associated epilepsy cases. An AED-induced reduction in the frequency of seizures was observed in 15.7 % of the patients. No one case – without effect. The greatest success in relieving seizures was seen in juvenile myoclonic epilepsy; childhood absence epilepsy was intermediate; the lowest percentage of remission was noted in juvenile absence epilepsy. The most effective drugs were valproic acid and ethosuximide used both alone and in combination. Lamotrigine, topiramate, and levetiracetam were used as part of combination therapy.