Abstracts

Rationale: The aim of this study was to characterize different motor patterns of hyperkinetic (HK) seizures and to investigate their possible different subtending anatomo-functional correlates. Methods: 60 patients presenting drug resistant epilepsy with HK seizures have been studied by video-EEG and stereo-EEG (SEEG) (52 cases), preliminary to epilepsy surgery; 699 seizures have been recorded. Video-EEG data allowing the analysis of HK manifestations underwent clinical and kinematic study, consisting in the estimation of displacement, speed and acceleration of body segments with a computerised system (Videopoint), to clarify the relationship between cyclic motor activity of trunk and proximal and distal parts of the four limbs. A study of correlation of the hyperkinetic manifestations with the topography of the SEEG discharge has been performed. Results: Based on the topography and the characteristics of the motor manifestations we have classified the HK seizures in 5 subgroups: 1) a symmetrical pattern (10 patients, 66 seizures), with bilateral HK movement of trunk and limbs; 2) an axial pattern (17 patients, 161 seizures), usually preceded by body pronation and mainly characterized by rhythmic oscillations of the trunk and minor involvement of the limbs; 3) an hemi-lateral pattern (14 patients, 131 seizures), with rhythmic, wild motor activity predominant in the limbs of one side and concomitant dystonic or hypertonic posturing of the contralateral one; 4) an hemi-vertical pattern (9 patients, 158 seizures), with HK manifestations prominently involving lower limbs, with hands usually immobilized behind the head or grasping; 5) a puppet pattern (10 patients, 183 seizures) with fragmentary, arrhythmic HK manifestations. Eight cases showed a slow motor activity, 5 of them post-surgical ablation. Kinematic analysis confirmed strong analogies in subgroups 1-4, with different somatic topography, and substantial qualitative differences in subgroup 5. SEEG analysis of the ictal discharged showed that the ictal onset zone could be extremely variable, but the symptomatogenic zone of HK manifestations was always located in the fronto-mesial region, with a strong involvement of the cingulate gyrus. Whereas subgroups 1-3 showed only minor differences in the ictal SEEG correlates, group 4 presented a concomitant fronto-temporal discharge, homolateral to HK manifestations, and group 5 had also prominent fronto-lateral discharge. Conclusions: Steaming from the concept that HK seizures represent an heterogeneous entity, we propose a clinical classification of HK patterns, possibly suggesting the ictal involvement of different motor circuits.