Abstracts

Rationale: Temporal lobe epilepsy (TLE), the most frequent localization-related epilepsy, usually starts in childhood or early adolescence. Hippocampal sclerosis (HS) is the most frequently observed pathologic substrate in these patients; however, there are few data on the pathological substrates in TLE of later age onset. We investigated clinical characteristics according to age of onset in patients with TLE. Methods: We found 409 patients who were diagnosed as having TLE from the Yonsei Epilepsy Registry database. The diagnosis of TLE was based on ictal semiology, EEG, and MRI. The patients was classified into young-age (< 25 years), middle-age (25 to 49), and old-age groups (?50) according to the age of onset. Results: Two hundred and twenty-eight patients (55.7%) were men, 269 patients (65.8%) were classified as symptomatic epilepsy and 176 patients (43.0%) were na ve to the antiepileptic drug (AED) treatment at their initial visit. The young-age, middle-age, and old-age groups consisted of 195 (47.7%), 146 (35.7%), 68 (16.6%) patients, respectively. The significant past histories included (permitting duplication) febrile seizure (FS) (n=53), CNS infection (n=45), head trauma (n=22), perinatal problem (n=11), stroke (n=5), brain surgery (n=3), hypoxia (n=2), posterior leukoencephalopathy (n=1). Brain MRI findings were as following: normal (n=159), HS or dual pathology (n=111), atrophic lesion (n=67) (48 with specific etiology), tumorous lesion (n=27), vascular malformation (n=21), malformation of cortical development (n=18), tuberous sclerosis (n=4), miscellaneous (n=2). Mean age of onset was 30.0 18.7 years. Patients with earlier age of onset were more likely to have history of FS, family history of epilepsy (n=26), mental retardation (n=15), and secondarily generalized tonic-clonic seizures (SGTCS). They were also more likely to be under AED treatment at their initial visit and have more frequent self-awareness of complex partial seizures (CPS) (if existed) (27.7 18.6 versus 37.0 18.5; 80.0%, 64.0%, and 56.6% in young-age, middle-age, and old-age groups, respectively). On the analysis of brain MRI findings, HS was more frequently found (40.0%, 18.5%, and 8.8%; p<0.001) in young-age group, whereas atrophic lesions being noted less frequently (9.7%, 22.6%, and 22.1%; p=0.002). Normal MRI was more frequent in old-age group (34.4%, 38.4%, and 52.9%; p=0.025). Conclusions: This study suggests some differences according to age of onset in clinical characteristics including causes and MRI findings in TLE patients. Higher frequency of normal MRI and untreated status, and lower frequency of SGTCS and patient awareness of CPS in patients with old-age onset may reflect a different epilepsy syndrome from that of childhood onset.