Among the generalized idiopathic epilepsies, the typical absence disorder, with its regularly recurring 3-per-second spike-and-wave EEG abnormality, begins in this age period (rarely before age 4 years) and carries a good prognosis. This seizure disorder responds well to medications, as indicated further on. Its features are fully described in “Absence Variants.”
Convulsions in this age group may present around the age of 4 years as focal myoclonus with or without astatic seizures, atypical absence, or generalized tonic-clonic seizures. The EEG, repeated if initially normal, is most helpful in diagnosis; it reveals a paroxysmal 2to 2.5-per-second spike-and-wave pattern on a background of predominant 4to 7-Hz slow waves. Many of these cases qualify as the Lennox-Gastaut syndrome, are difficult to treat, and are likely to be associated with developmental delay. At this age, perhaps more than any other, the first burst of seizures may take the form of status epilepticus and, if not successfully controlled, may end fatally.
These represent a common problem in practice but present a special difficulty because this is the age at which syncope and psychogenic seizures begin to occur and alcohol and drug abuse may begin. In this age period in particular, as the adolescent strives for independence, the social disruption caused by seizures are likely to take a toll on the relationships and educational progress of the emerging adult. Here, we also face the frequent issue relating to the nature and management of the first seizure in an otherwise normal young person. As in other age groups, the history often discloses the likely provocation of seizures, as for example, in young person has been sleep deprived or imbibing alcohol or one of many abused drugs and has a first seizure. A search for a cause of the first seizure in this age group is necessary by MRI, ECG, and EEG but these tests less frequently disclose an underlying lesion than in other age groups. Often, there has only been a single event and no clinical or EEG features to define the nature of the seizure disorder. However, the type of seizure that first brings the child or adolescent to medical attention is most likely to be a generalized tonic-clonic convulsion and may mark the beginning of idiopathic generalized epilepsy or juvenile myoclonic epilepsy, as described earlier sections.
A few patients have had a history of absence in which the EEG shows a characteristic polyspike pattern, about one-third with a photomyoclonic response. When the seizures are an expression of a congenital epileptic focus that is associated with developmental delay or scholastic failure, the diagnostic and therapeutic problem becomes demanding. In the special group of younger individuals with long-standing seizures, nearly half have temporal lobe epilepsy. Huttenlocher and Hapke, in a follow-up study of 145 infants and children with intractable epilepsy, found that the majority had developmental delay.
Opinion is divided on whether treatment is required for the older child or adolescent who comes to medical attention because of a first seizure that appears to be idiopathic. Age, sex, and the circumstances of the seizure (withdrawal from drugs or alcohol, myoclonic episodes, family history) all figure into the risk of subsequent seizures. What is apparent is that the early use of antiepileptic drugs has little effect on the occurrence of later seizures, as summarized in guidelines authored by Krumholz and colleagues as discussed further on. When such cases have been observed without treatment, such as in the series reported by Hesdorfer and colleagues, the risk of another seizure over 10 years was 13 percent unless the first episode was status epilepticus, in which case the risk was 41 percent. Attention is given to regularizing sleep and minimizing alcohol and stimulants.