Seizure duration was determined in a prospective study of 407 children with a first unprovoked seizure treated at the Epilepsy Management Center, Montefiore Medical Center, Bronx, NY. Analysis of medical and ambulance records and structured interview showed that 50% of seizures were >5 minutes duration, >10 min in 29% of cases, >20 min in 16%, and >30 min in 12%. Children were not taking antiepileptic drugs at the time of the seizure, and except in some with status epilepticus, the seizure stopped spontaneously. Two groups of patients were defined, one with a mean of 3.6 minutes, short duration seizures (76% of cases) and the other with a mean duration of 31 minutes (24%) and a predisposition to prolonged seizures. Seizures were less likely to stop spontaneously if they lasted longer than 5-10 minutes. In patients with 2 or more seizures (182), the duration of first and second seizures were highly correlated (P<.0001). Intervention AED therapy is indicated once a seizure lasts for >5-10 minutes. The definition of status epilepticus as a seizure lasting for 30 minutes or longer appears to be supported. 
COMMENT. Seizures lasting >30 minutes are not infrequent in children with a first unprovoked untreated seizure. Spontaneous remission is unlikely when a seizure is allowed to continue for more than 5-10 minutes. The authors recommend treatment after a seizure has lasted for 5-10 minutes. In fact, since treatment is less effective the longer a seizure lasts, why wait to treat?
The prevalence of long duration seizures among patients monitored with refractory partial epilepsy is lower than in those with first unprovoked attacks. Most secondarily generalized tonic-clonic seizures last for <2 min and those >5 min are infrequent. These observations have suggested a need for possible revision of the definition of status epilepticus to a seizure lasting =/>5 minutes . Shinnar and colleagues favor the current definition (a seizure lasting =/> 30 min), except perhaps for refractory localization-related epilepsies.