PURPOSE: Before 1986, the spectrum of childhood epilepsies, including 
Lennox-Gastaut syndrome (LGS) and Doose syndrome (DS), known collectively as 
"epilepsia myoclonica astatica," was believed to represent a single disease. 
More recently, some investigators have considered these syndromes to be parts of 
a continuum. To clarify these theories, neurobiologic factors of the syndromes 
were studied to determine which qualities were shared and which were unique.
METHODS: A retrospective (1975-1985), community-based (Helsinki metropolitan 
area and the province of Uusimaa) study was designed to seek children with 
features of LGS and DS. It was assumed that recall bias and the selection of 
documented history would be similar throughout the group. Ranks of increasing 
pathology were assigned to different seizure types, EEG results, and drug 
treatments. A similar procedure was applied to epidemiologic data. Spearman 
rank-order correlations were calculated to determine which features correlated 
with LGS and which correlated with less severe epilepsy.
RESULTS: The survey comprised 75 patients with broadly defined LGS. The annual 
incidence was 2 in 100,000 children aged 0 to 14 years. Prenatal or perinatal 
abnormalities did not correlate with severity of epilepsy. As compared with the 
relatively favorable ranks, the severe epilepsy ranks were more often associated 
with an early onset of epilepsy, an infectious disease at the onset, delayed 
development before epilepsy, abnormalities in neurologic or neuroradiologic 
examinations, and a deteriorating course of the condition.
CONCLUSIONS: Patients with LGS are more likely than patients with less severe 
epilepsy to have a younger age at onset of epilepsy, an infection or both, and a 
deteriorating course of the condition.