Abstracts

Rationale: Electrodecremental event (EDE) is defined as low-voltage fast activity or widespread redunction in the amplitude of electrical background activity and is termed 'diffuse voltage attenuation' or 'diffuse flattening' of the electroencephalographic (EEG) activity. EDE has been described as a seizure pattern in infantile spasms, in atonic seizures, in tonic seizures and in seizures of the Lennox-Gastaut syndrome. Also, most of patients with EDE have undergone severe intractable seizures. This study investigated to assess the relation of the different patterns of EDE with clinical outcome, especially in aspect of the response to treatment in childhood epilepsy. Methods: We reviewed the EEG records of the 27 childhood epilepsy with EDE on initial interictal EEG before start of the antiepileptic drugs (AEDs). The patients with no clinical seizure and no relapse for more than 6 months after AEDs therapy were appointed as 'group of the patients with controlled seizure' (group A, 11 patinets). The others were appointed as 'group of the patients with uncontrolled seizure' (group B, 16 patients). Between group A and group B, several clinical and EEG findings were compared and analyzed, as followings: sex, seizure type, etiology of epilepsy, age at the first seizure onset (Age-1), age at the start of AEDs (Age-2), developmental delay, preceding abnormal activity followed by attenuated activity in EDE (Pre-EDE), voltage of attenuated activity (V-EDE) and duration of attenuated activity (D-EDE). Results: The mean of Age-1 was 2.87 years in group A and was 1.36 years in group B (P=0.051). The mean of Age-2 was 3.38 years in group A and was 1.49 years in group B (P=0.047). Polyspike-and-wave pattern in Pre-EDE was found in no patient (0/11, 0%) in group A and in 5 patients (5/16, 31%) in group B (P=0.040). V-EDE under 20 mcV was found in 18% (2/11) in group A and in 50% (8/16) in group B (P=0.090). The mean of D-EDE was 1.42 seconds in group A and was 1.43 seconds in group B (P=0.985). Conclusions: Conclusively, of the childhood epilepsy with EDE on initial interictal EEG before AEDs therapy, the patients with uncontrolled seizure showed the relation to the early onset of epilepsy, younger age at start of the AEDs, polyspike-and-waves followed by attenuated activity and relatively lower-voltage attenuated activity rather than patients with controlled seizure.