Abstracts

Rationale: Temporal lobe epilepsy (TLE) is said to be the most common epilepsy syndrome but detailed incidence and prevalence data is difficult to obtain specifically for mesial TLE (MTLE) because the diagnosis requires knowing detailed data, such as MRI and EEG results, that are not available from population studies. Therefore, we examined the prevalence of TLE compared to other defined epilepsy syndromes from a database of well-characterized patients.Methods: The University of Virginia Epilepsy Database from April 1, 1998 to November 30, 2004 was reviewed in order to determine the percentage of all patients with specific epilepsy syndromes. Syndromes with more than 10 patients were included. Analysis was limited to patients with definite epilepsy and at least 5 years old at the time of initial database entry. Results: Out of 1639 patients, 967 (59.5%) had focal epilepsy, 602 (37%) had generalized epilepsy and 61 (2.3%) had mixed epilepsy. Prevalence of specific epilepsy syndromes are: cryptogenic localization related epilepsy (CLRE) 257 (15.7%), non-mesial TLE 133 (8.1%), MTLE 111 (6.8 %), frontal 55 (3.4%), parietal 29 (1.8%), occipital 14 (0.9%), benign Rolandic 19 (1.2%), JME 81 (4.9%), cryptogenic generalized 68 (4.1%), LGS 48 (2.9%), childhood absence 28 (1.7%), and juvenile absence epilepsy 10 (0.6%).Conclusions: There is no specific epilepsy syndrome that occurs in the majority of epilepsy patients or even in a large minority. Cryptogenic localization related epilepsy is the single most common identifiable syndrome. Among focal epilepsies, non-mesial TLE is the most common syndrome followed by MTLE but JME is the most common generalized epilepsy syndrome followed by LGS. The low prevalence of MTLE may explain why temporal lobectomy is becoming less frequently performed as the back-log of MTLE patients has been operated on during the growth of epilepsy surgery programs, now limiting the procedure to newly diagnosed cases.This implies that animal and human research should focus less on MTLE and more on neocortical and other epilepsy syndromes.