Children with childhood epileptic
encephalopathy (
Lennox-Gastaut syndrome) frequently have both multiple seizure types and nonepileptic stereotyped events that are difficult to differentiate. We hypothesize that electroencephalogram (EEG) video monitoring is essential for correct identification of atypical absence
seizures in this population. All video/EEG monitoring records on patients with confirmed
Lennox-Gastaut syndrome between September 1992 and December 1996 were reviewed for clinical events and EEG changes. A subset of patients with suspected atypical absence
seizures during the video/EEG formed the cohort for analysis. Thirty-eight patients had 48 monitoring periods ranging from 1 to 4 days (mean, 2.2 days). Twenty-six monitoring periods captured suspected atypical absence
seizures and formed the study cohort. Suspected atypical absence
seizures were epileptic
seizures in only 27% (7 of 26) of the study cohort. By contrast, parents reliably and correctly identified tonic, atonic, and
tonic-clonic seizures in the study cohort. Reliable diagnosis and subsequent counting of atypical absence
seizures in patients with
Lennox-Gastaut syndrome cannot be made on the basis of observation and/or history alone. Future outpatient studies of investigational
anticonvulsant medications for patients with
Lennox-Gastaut syndrome should consider parental counts of atypical absence
seizures unreliable. We recommend that video/EEG monitoring be done on all
Lennox-Gastaut syndrome patients with suspected atypical absence
seizures not controlled by medication.