The purpose of this article is to present a short review of the natural history 
of myoclonic astatic epilepsy (MAE; Doose syndrome) and the Lennox-Gastaut 
syndrome (LGS). In the 1989 classification of the International League Against 
Epilepsy (ILAE, 1989), MAE and LGS were initially included in group 2.2: 
"Cryptogenic or symptomatic generalized epilepsies and syndromes." The 
subsequent classification of the Proposed Diagnostic Scheme for People with 
Epileptic Seizures and with Epilepsy (see Ref. 8) placed MAE in axis 3 in the 
"generalized epilepsy" group and LGS, severe myoclonic epilepsy of infancy (SMEI 
or Dravet syndrome) and atypical benign partial epilepsy/pseudo-Lennox syndrome 
(ABPE/PLS) in the "epileptic encephalopathy" group. The semiology of MAE and LGS 
and their differential diagnosis from SMEI and ABPE/PLS are described. Before 
the onset of SMEI, MAE, and ABPE/PLS, the development of the child is usually 
normal. In contrast, in LGS, development is frequently retarded at the onset, 
depending on the etiopathogenesis of the underlying brain disease. The course of 
MAE is highly variable with regard to seizure outcome (complete remission in 
some cases, persistent epilepsy in others) and cognitive development (normal or 
delayed). The course of LGS and SMEI is generally poor, both with regard to the 
epilepsy and to the cognitive development whereas the course and seizure outcome 
of ABPE/PLS is favorable; the patients will be seizure-free at puberty. However, 
the neuropsychological outcome is less favorable; most patients remain mentally 
retarded.