Evolution of childhood absence epilepsy, juvenile myoclonic epilepsy and epilepsy with grand mal on awakening.

Seventy-one Chinese children with idiopathic generalized epilepsy, from among 1931 pediatric epileptics, were reviewed clinically and electroencephalographically. They were classified under childhood absence epilepsy (CAE, 50/71), juvenile myoclonic epilepsy (JME, 7/71) and epilepsy with grand mal on awakening (GMA, 14/71). All the patients' family members with epilepsy were classified under idiopathic generalized epilepsy. Hyperventilation was the most common precipitating factor for CAE, and sleep deprivation was the most common one for JME and GMA. Electroencephalographically, fast generalized spike or polyspike-wave complex (> or = 3Hz) was the most common feature. Three JME (42%) and 4 GMA patients (28%) had been diagnosed as CAE about 5 to 7 years preceding JME and GMA, respectively. Sixteen CAE cases (32%) later evolved to be GMA. All JME patients had concomitant GMA and three GMA cases (21%) had concomitant JME at diagnosis. There is strong evolutional correlation among CAE, JME and GMA in this series.