Abstracts

Population based epilepsy studies provide accurate estimates of incidence and prevalence but provide limited data about precise seizure type and epilepsy syndrome characteristics because a detailed seizure history and prior antiepileptic drug (AED) use can[apos]t be obtained. We prospectively collected data on a finite epilepsy population to determine the characteristics defining each seizure type and epilepsy syndrome. Standardized data were prospectively collected by epileptologists from patients seen in the UVA Epilepsy Clinic from April 1998 to November 2004. Data was acquired directly from patients and medical records, then refined and cleaned by standardized methods and updated at each clinic visit. Analysis was limited to patients with definite epilepsy 5 years old or greater. Data collected included demographics, ILAE seizure (SZ) type, ILAE epilepsy syndrome, etiology, EEG, neuroimaging, family history, and current and prior antiepileptic drug use. Patients were categorized into 14 classes by the combination of SZ types they possessed. SZ frequency of each SZ type was plotted over time from June 2000 to November 2004. A total of 1638 patients were analyzed. Overall, mean current age is 31.9, mean age at seizure onset was 14.4, and 49% are female. An etiology is known in 16% and 49% had a family history of epilepsy. Median current SZ frequency is 3/mo. The median for the highest monthly frequency ever reported by patients is 5/mo and for the minimum seizure frequency ever reported is 1/mo. Patients most frequently reported having only partial-onset SZ (60%) compared to only generalized SZ (37%) and mixed partial and generalized SZ (4%). Among the 14 categories of SZ combinations, CPS + Secondarily Generalized (25%) and Multiple Generalized (17%) are most common. The most common syndromes are Symptomatic Localization-Related Not Further Classifiable (17%), Cryptogenic Generalized Not Further Classifiable (16%), Idiopathic Generalized Not Further Classifiable (8%), and MTLE (7%). Other specific syndromes were less frequent. The mean number of AED ever used is 4. AEDs are not used at all by 9% while 19% use three or more AEDs. 47% patients previously failed three or more AEDs. Patients with only generalized SZ more commonly are off all AEDs (11%). It is well know that partial-onset seizures are more common and this clarifies that CPS + secondary generalization is the single most common combination of SZs. The etiology of epilepsy is rarely identifiable and most patients do not fit into a specific syndrome but MTLE is the single most common specific syndrome. A surprising minority of patients was not on AEDs but nearly half have failed 3 AEDs. (Supported by University of Virginia Comprehensive Epilepsy Program.)