A retrospective study of carbamazepine therapy in the treatment of idiopathic generalised epilepsy

Abstract

Objective: The exacerbation of idiopathic generalised epilepsy (IGE) by some anti-epileptic drugs (AEDs) such as carbamazepine (CBZ) has been well documented. However, it is unclear whether IGE is always worsened by the use of CBZ, or whether some patients with IGE benefit from its use. Methods: Using an Epilepsy Electronic Patient Record, we retrospectively identified all patients with IGE attending our service that had been on CBZ therapy. The response to CBZ was recorded as one of four categories – seizure freedom, improved seizure control, no effect, and seizure exacerbation. The reasons for discontinuing CBZ were also recorded, if relevant. To see if there were differences between those who did and did not respond, we assessed: clinical features, seizure semiology, EEG findings, IGE subtype, and use of other AEDs. Results: Data were obtained at the end of December 2010. At that time, data were available for 154 patients with IGE. Of these, 16 (10.4% of IGE patients) had taken CBZ. Nine patients in this group were female, and mean age was 37.3 years (range 18–70). All patients were right handed. Patients had various seizure semiologies. Six patients had myoclonic seizures, 14 had generalised tonic clonic seizures and 7 had generalised absence events. EEGs were normal (25%) or showed generalised discharges without focal features (75%). The IGE types seen were juvenile myoclonic epilepsy (10 patients), juvenile absence epilepsy (one patient), generalised epilepsy with tonic clonic seizures only (one patient), and IGE not otherwise classified (four patients). Ten patients had stopped CBZ, but in only one (6.3%) was this due to seizure exacerbation. Six patients (37.5%) were still on CBZ in combination with other AEDs, and had seizure improvement (4 patients – 25%) or seizure freedom (2 patients – 12.5%). Three of these six had failed trials of weaning CBZ. There was no significant difference in clinical features between those who had seizure improvement / seizure freedom on CBZ and those who did not. Conclusion: Although the number of patients in our series is small, we feel that it illustrates that CBZ may still have a therapeutic role in IGE. However, the rate of seizure improvement / freedom in our series is higher than in others reported, and we cannot explain this. We have not identified any features associated with response to CBZ, and we feel that the reasons for the success or failure of CBZ therapy in IGE merit further investigation.