Abstracts

Rationale: Approximately one-quarter of patients with refractory partial epilepsy suffer from frontal lobe seizures. Characteristic semiological findings in these seizures are hypermotor, unilateral clonic and tonic asymmetric elements. We aimed to analyze associations between incidence of certain semiological features and different age groups.Methods: This is a retrospective study reviewing electronic clinical records of 216 cases undergoing video-EEG-monitoring for frontal lobe seizures at the Epilepsy center of the Albert-Ludwigs-University Freiburg, Germany between September 2000 and November 2014. Subject of study were patients with exclusively frontal lobe epilepsy (82 cases, 46 male). Semiological signs and symptoms were coded for a maximum of 10 seizures per patient, lumped per individual and analyzed at age groups 0-8 (n1=11), 9-15 (n2=17), and >15 (n3=54) years.Results: Mean age at time of observation was 24 years (range 2-55 years), median 23 years. Across all age groups most common semiological characteristics included unilateral tonic posturing (52%), bilateral tonic posturing (44%), vocalization (42%) and unilateral clonic posturing (33%). Auras were typically reported in the oldest age group (p=0.017). Occurrence of hypomotor seizures (p=0.038), bradycardia (p=0.038) and vomiting (p=0.038) were seen significantly more frequent in the youngest age group. Unilateral tonic posturing during seizures showed a peak value of incidence in the middle age group (p=0.037). Trend for more frequent occurrence of versive head seizures and lateralized cloni at the end of bilateral tonic-clonic seizures were observed in the older age groups. Two patients monitored at different points of age displayed an evolution of semiological signs as they presented tonic posturing bilateral at younger age and unilateral as they got older.Conclusions: Different semiological subgroups in frontal lobe epilepsy, their relation to anatomic organization and whether seizures can be localized based on semiological signs has already been researched in detail. Yet, reviewing the literature, there was a lack of agreement. Early asymmetric tonic posturing however seems to be constantly related contralateral to the side of seizure origin. Occurrence of contralateral clonic movement, uni- or bilateral tonic motor activity and complex automatism are listed as typical findings in frontal lobe seizures in literature. Larger research on semiological alterations in different age groups is missing so far. Our results in this cross-sectional study indicate an age dependence of several semiological signs in frontal lobe epilepsy. Especially lateralizing signs and auras were not common in very young patients. Changes in motor signs may represent maturation of connectivity within and beyond the frontal lobe, whereas the latter may be due to a reporting and observation bias.