Abstracts

The natural history of epilepsy, and particularly the rate of seizure freedom (SF), is generally unknown except in a few specific epilepsy syndromes. The rate of SF is generally regarded to be low if patients do not respond to the first two medications. However, our experience suggests that some patients with refractory epilepsy become SF. We hypothesized that the rate of SF is higher than expected and correlated with the seizure class and epilepsy syndrome., Standardized data were prospectively collected by epileptologists from established and new patients seen in the UVA Epilepsy Clinic from April 1998 to November 2004. Data were acquired directly from patients and medical records, refined and cleaned by standardized methods and updated at each clinic visit. Analysis was limited to patients with definite epilepsy [gt] 5 years old. Frequency of each seizure (SZ) type was collected at each visit. Patients were categorized into 14 classes by the combination of SZ types they possessed and classified by ILAE syndromes. For each subject, monthly SZ frequency of each SZ type was plotted over time for the study duration. SF was defined as a total frequency of 0 for at least 6 mo. in patients who had at least 3 SZ frequency entries., From 1638 subjects, 988 had 3 or more SZ frequency entries and were followed for a mean of 37 mo. SF developed in 25% (243), established SF was present throughout the time period in 23% (231), and 52% (514) continued to have seizures. Among those SF, mean duration of follow-up was 24.5 mo. and mean duration of SF was 20.9 mo. The majority (56%) of those SF had a moderately high baseline SZ frequency of 1-15/mo, while 21% had [lt]1/mo and 15% had a very high SZ frequency of [gt]15/mo. Subjects with GTCs only were most likely to have a low SZ frequency (60%) and mixed types to have a very high frequency (67%). SF rate was highest for subjects with generalized SZs (113 of 355 subjects or 31%) and lowest for mixed SZs (6 of 28 subjects or 21%). SF rate was highest for idiopathic localization-related (53%) and idiopathic generalized (38%) and lowest for other generalized epilepsies (25%)., An overall rate of seizure freedom of 48% with 25% becoming SF during the study period is higher than generally expected for established epilepsy. Patients with only generalized SZs, or idiopathic generalized and idiopathic localization-related epilepsies are more likely to become SF but some rate of SF develops in all SZ types and syndromes. It is likely that recall bias and other factors give clinicians the impression that only few patients with epilepsy are seizure free. This demonstrates that SF is a reasonable goal in the treatment of established epilepsy, depending on the SZ type and epilepsy syndrome., (Supported by University of Virginia.)