Abstracts

Rationale: Hippocampal sclerosis (HS) is a common feature in Temporal Lobe Epilepsy (TLE). The majority of studies accomplished in the past decade indicate that TLE with HS can be considered as an epileptic condition different from other focal TLEs. However, the question whether TLE with HS is a unique biological entity is not yet answered. The aim of this study was to compare phenotypic characteristics of TLE patients with and without HS. Methods: 218 patients were diagnosed with TLE using the ILAE criteria. Only patients of Caucasian race and age over 18 year’s were included. The patients completed a standardized evaluation form, and a case record form was completed by a doctor or nurse. Epidemiological data and clinical features were compared. Results: 56 (25.7%) patients were diagnosed with HS versus 162 patients (74.3%) without HS. Age at epilepsy onset was lower in patients with HS (p=0.002), with 50% onset before age of 6 years in HS patients, in contrast to 23.4% in non-HS patients. Incidence of simple partial seizures (p=0.002) and complex partial seizures (p=0.002) was significantly higher in the HS-group. However there was no difference in generalized tonic-clonic seizures. Incidence of ictal psychiatric symptoms (p=0.015) as well as autonomic symptoms (p<0.001) were higher in TLE patients with HS. There was neither any significant difference in frequency and appearance of ictal motor symptoms, nor in ictal somatosensory or special-sensory symptoms. Interictal standard EEG showed no difference between the two groups. There was a higher appearance of childhood febrile seizures in patients with HS (p=0.043). In contrast, patients without HS appeared to have more family members with febrile seizures in childhood (p=0.019). Conclusions: Our study identified significant differences in patients with HS regarding epidemiological, clinical and diagnostic aspects supporting that TLE with HS is a unique biological entity. A proper classification of subgroups in TLE and a clear definition of “key features” in TLE with HS are important in diagnostic-, treatment- and prognostic terms, and deliver crucial information to future phenotype-genotype studies.