Altered synchrony and loss of consciousness during frontal lobe seizures.
OBJECTIVE
Loss of consciousness (LOC) in frontal lobe epilepsy (FLE) has been rarely specifically studied until now. In this study we evaluated the LOC in a population of patients with FLE and studied the relationship between changes in synchrony and degree of LOC.


METHODS
24 patients undergoing stereoelectroencephalography (SEEG) during pre-surgical evaluation of FLE were studied. The LOC intensity was scored using the Consciousness Seizure Scale (CSS). For each studied seizure (n=52), interdependencies between signals recorded from 5 brain regions were estimated as a function of time by using non-linear regression analysis (h(2) coefficient).


RESULTS
Seizures were divided into 3 groups according to the CSS scale: group A (no LOC) with a score ⩽2, group B (intermediate or partial LOC) with a score ranging from 3 to 5, and group C (maximal LOC) with a score ⩾6. The majority of seizures in FLE patients disclosed significant LOC, particularly for patients with prefrontal lobe seizures. Mean correlation values were significantly different between groups A and C (p<0.001), the maximal values of synchrony being observed in group C. Differences were significant for interaction affecting the external prefrontal cortex (p=0.004) (p=0.01) and the parietal cortex. In addition, a significant correlation was found between CSS scores and correlations values (h(2)) of the prefrontal and the parietal region but not with the premotor cortex.


CONCLUSIONS
This study indicates that in FLE, prefrontal seizures frequently alter consciousness. As in other focal seizures, LOC appears to be related to changes in synchrony in prefrontal and parietal associative cortices.


CONCLUSIONS
LOC in FLE is frequent and as in other focal epilepsies is related to an alteration of prefrontal-parietal network.
CHU Timone, Service de Neurophysiologie Clinique, Assistance Publique des Hôpitaux de Marseille, Marseille 13005, France; "Institut de Neurosciences des Systèmes, INSERM UMR 1106", France.
Francesca
F
Bonini
CHU Timone, Service de Neurophysiologie Clinique, Assistance Publique des Hôpitaux de Marseille, Marseille 13005, France.
Isabelle
I
Lambert
INSERM, U642, Université Rennes 1, Rennes, France.
Fabrice
F
Wendling
CHU Timone, Service de Neurophysiologie Clinique, Assistance Publique des Hôpitaux de Marseille, Marseille 13005, France; "Institut de Neurosciences des Systèmes, INSERM UMR 1106", France.
Aileen
A
McGonigal
CHU Timone, Service de Neurophysiologie Clinique, Assistance Publique des Hôpitaux de Marseille, Marseille 13005, France; "Institut de Neurosciences des Systèmes, INSERM UMR 1106", France; Hôpital Henri Gastaut/Centre Saint-Paul, CINAPSE, 300 Bd Sainte-Marguerite, 13009 Marseille, France. Electronic address: fabrice.bartolomei@ap-hm.fr.
Fabrice
F
Bartolomei
D000293:Adolescent; D000328:Adult; D002648:Child; D004569:Electroencephalography / Q000379:methods; D017034:Epilepsy, Frontal Lobe / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012640:Seizures / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D014474:Unconsciousness / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D055815:Young Adult
Consciousness; Focal epilepsy; Frontal cortex; Synchrony