Posttraumatic Epilepsy

In recent years, whether pediatric TBI survivors should be treated with antiepileptic drugs (AED) prophylacti- cally has been discussed frequently in the literature. Seizures after TBI are separated into immediate, early, and late posttraumatic seizures.

In adults who have TBI, early seizures correlate with the development of late seizures. However, this correlation is not seen in the pediatric population after brain injury (196). The incidence of posttraumatic sei­zures is greater in children than in adults. Although the majority of posttraumatic seizures in children are immediate seizures, the incidence of early seizures ranges from 20% to 39% (54, 196, 197, 198) and the incidence of late seizures ranges from 7% to 12% (196, 199, 202). It should also be noted that lower GCS and younger age are associated with a higher risk of early posttraumatic seizure (54, 196, 197, 198, 200). Children less than 2 years of age have a three-fold greater risk of early posttraumatic seizures compared with children who are 2-12 years of age (197). In one study of chil­dren who were 3 years of age and younger at injury, the risk of late posttraumatic seizures was greatest in the children who were under 1 year of age at the time of injury (55).

Consensus guidelines established in 2003 state that currently there is insufficient data to support a standard guideline for the prevention of pediatric posttraumatic seizures (201). The guidelines recom­mend that prophylactic AED not be used to prevent the development of late seizures. They did note, how­ever, the bulk of the evidence does suggest considering AED as a treatment option to prevent early seizures in high-risk patients. The American Academy of Physical Medicine and Rehabilitation agrees that “[a]ntiepilep- tic drugs are not recommended after one week for sei­zure prophylaxis in nonpenetrating traumatic brain injuries.” Young et al.

Posttraumatic epilepsy is diagnosed when the patient has two or more seizures in the late period after TBI. For the child who transfers to the pediatric rehabilitation medicine unit on phenytoin or another AED, the process of weaning the medication is fairly simple. If serum levels of the AED are subtherapeutic, it is safe to discontinue the medication without wean­ing. Otherwise, the dose can be reduced by approx­imately 50% the first week and can be discontinued thereafter. Since early seizures in children are not cor­related with the development of late seizures, one can obtain an EEG in children who had early seizures and if no epileptiform activity is identified, consideration can be given to weaning the antiepileptic drug (166).

In children who develop posttraumatic epilepsy, AED therapy should use medications that have the least effect on cognitive function. This medication should then be used at the lowest clinically effective dose in order to maximize the cognitive recovery of these patients. The consulting pediatric neurologist considers which AED to use in a given child based on factors including the clinical seizure pattern, the EEG activity, and the side effect profile of the AED.