Abstracts

What constitutes intractable epilepsy remains controversial. The prevailing consensus is failure of seizure control after trial of 2 or more antiepileptic drugs. Though it is widely felt that [ldquo]rational[rdquo] therapy should be employed, previous studies have not specifically looked at the impact of mechanism of action of antiepileptic drugs in helping further define and characterize intractability. A review of the database of all active pediatric epilepsy patients followed at our center between January 2003 and April 2004 was made. Patient charts were reviewed for further information. At the time of this abstract submission, 511 pediatric patients were on seizure medication or had been weaned off during the data collection period. Two hundred and four patients (40%) were on a stable dose or being titrated on the first AED. One hundred and four patients (20%) were on a second AED, and 33 (6%) were on a third AED. Thirty-five patients (7%) had a second drug added. Twenty-seven patients (5%) were on a second and third drug combination.
Seizure freedom was defined as no seizure for more than one year. One hundred and sixty-two of 511 patients (32%) were seizure free. Of these, 82 (50%) achieved seizure freedom after institution of the first drug, 44 (27%) after the second AED, 5 (3%) after the third, and 8 (5%) with the fourth AED. For patients on combination therapy, 11 (7%) were seizure free on the first two AEDs, and 5 (3%) achieved seizure freedom on a second and third drug combination.
Of the 44 patients who were seizure free on the second AED, 15 were on the second drug because of poor seizure control and 9 due to side effects. The others had only transient exposure or were weaned from their first AED. Conversion from a narrow spectrum drug (phenytoin, carbamazepine) to a broad spectrum drug (eg. topiramate, lamotrigine) or the converse did not influence seizure freedom in the 15 patients who were on a second drug due to incomplete efficacy. In fact, 4 of 15 were placed on oxcarbazepine from carbamazepine, both considered narrow spectrum drugs. Seizure freedom in 32% of pediatric patients is less than reported previously in prospective studies. This may in part be due to our data collection process which includes both retrospective and prospective data, thus incorporating longer seizure histories.
Similar to previous studies, our results show a dramatic decline ([lt]5%) of achieving seizure freedom by the time a third drug is utilized.
Though rational polytherapy is encouraged, our data analysis does not substantiate this rationale. This may in part be due to incomplete data analysis at the time of this abstract submission.